CN118438459B - Cooperative control system of large-scale ferrofluid droplet robot - Google Patents
Cooperative control system of large-scale ferrofluid droplet robot Download PDFInfo
- Publication number
- CN118438459B CN118438459B CN202410917484.XA CN202410917484A CN118438459B CN 118438459 B CN118438459 B CN 118438459B CN 202410917484 A CN202410917484 A CN 202410917484A CN 118438459 B CN118438459 B CN 118438459B
- Authority
- CN
- China
- Prior art keywords
- robot
- droplet
- ferrofluid
- magnetic field
- robots
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Manipulator (AREA)
Abstract
The invention provides a cooperative control system of a large-scale ferrofluid droplet robot, which precisely controls a droplet robot group with superparamagnetism through a distributed magnetic field. The system comprises a driving module, a control module and a robot detection-tracking-positioning module, and realizes programmable reconstruction, separation, combination and shape change. The driving module utilizes the electromagnet array to generate a local nonuniform gradient magnetic field to perform addressable operation and precise control. The control module synchronously manages the distributed magnetic field, and the detection module feeds back the position information of the robot in real time through the vision system, so that closed-loop control is realized. The system is suitable for complex environments and minimally invasive surgery, and improves the operation precision and application potential of the ferrofluid droplet robot.
Description
Technical Field
The invention relates to the field of micro-nano robots suitable for medical operation, in particular to a cooperative control system of a large-scale ferrofluid droplet robot.
Background
The miniature soft robot driven by the magnetic field can be subjected to programmable deformation, realize multiple modes of motion and operation functions, and can directly enter the living body which cannot be reached or is difficult to enter at present to perform minimally invasive medical operation. However, existing elastomer-based micro-soft robots are limited in deformability, and are difficult to traverse a narrow limited space much smaller than themselves; furthermore, their function is constrained by pre-designed shapes and cannot accommodate complex and varied task requirements.
It should be noted that the information disclosed in the above background section is only for understanding the background of the application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.
Disclosure of Invention
The main object of the present invention is to overcome the above-mentioned drawbacks of the background art and to provide a cooperative control system for a large-scale ferrofluid droplet robot.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a cooperative control system for a large scale ferrofluid droplet robot, comprising:
The ferrofluid droplet robots have superparamagnetism and liquid properties, can generate an induced magnetic moment under the action of an external magnetic field, realize alignment with the direction of the external magnetic field, can minimize internal energy by changing shapes, and can receive magnetic force positively related to the volume of the ferrofluid droplet robots under the magnetic field gradient; the ability to have programmable reconfiguration, including separating, merging, and transforming shapes;
The driving module comprises a plurality of electromagnets arranged in an array and a current driving plate connected with each electromagnet, wherein the current driving plate can independently control the magnitude and the direction of current to each electromagnet so as to generate a distributed magnetic field, and realize addressable operation and group cooperative driving of a plurality of ferrofluid droplet robots; wherein, the coil of each electromagnet can generate a local nonuniform gradient magnetic field to act on the nearby droplet robot;
the control module is communicated with the current driving plate and is used for managing the operation of the whole cooperative control system, and the control module comprises a distributed magnetic field generated by a plurality of electromagnets in a synchronous control mode so as to realize accurate control and coordinated movement of the ferrofluid droplet robot group;
The robot detection-tracking-positioning module is in communication connection with the control module, and captures real-time position information of each unit in the ferrofluid droplet robot group by utilizing a vision system to detect, track and position multiple targets of the ferrofluid droplet robot group so as to realize closed loop feedback control; the control module adjusts a distributed magnetic field generated by an electromagnet array communicated with the current drive plate according to the real-time position information of each ferrofluid droplet robot provided by the robot detection-tracking-positioning module so as to accurately control the cooperative motion of the ferrofluid droplet robot group.
In some alternative embodiments, the method further comprises generating a predefined path for the population of ferrofluid droplet robots, using a collision search based algorithm to plan a path based on the starting and target positions of the population of ferrofluid droplet robots, and planning a collision-free path for the robot formation under constraint conditions based on the position of each robot.
In some alternative embodiments, the motion planning module utilizes a multi-agent path planning method, comprising two search processes, a top-level search that adds constraints to each robot and a bottom-level search that plans a path for each robot under constraints until collision-free paths that meet all the constraints occur.
In some optional embodiments, the motion planning module establishes a simulation environment of the real working space by using a grid map method, and maps the path points to the real working space again after completing path planning aiming at a discrete motion mode of the robot point to point, so that the droplet robot formation can complete a cooperation task according to the planned path.
In some optional embodiments, the motion planning module further includes a static obstacle avoidance strategy for path planning when there is a static obstacle in the workspace, specifically including:
an obstacle position information acquisition unit for detecting and acquiring position information of a static obstacle in the working space;
The safety distance constraint condition making unit is used for making safety distance constraint according to the position information of the obstacle, so as to ensure that the robot keeps a preset safety distance with the obstacle in the moving process;
The bottom layer planning unit is used for carrying out bottom layer searching under the constraint condition added by the top layer searching, planning a collision-free path avoiding the obstacle for each robot, and enabling each path to meet the safety distance constraint condition so as to realize the safety cooperation of multiple robots in the working environment with the static obstacle.
In some alternative embodiments, the system employs one or more of the following cooperative control strategies:
planning a collision-free path for the droplet robots by using each electromagnet in the distributed magnetic field as a potential path point, wherein the motion of each droplet robot is driven by a local magnetic field generated by the independently controlled electromagnet;
Utilizing a multi-robot path planning algorithm based on conflict search to realize position interchange among droplet robots so as to adapt to path planning and task requirements;
In the motion process, a plurality of selectable motion states are provided for the droplet robot, and distance constraint is added, so that the distance between the centers of any two robots is ensured to be always larger than the diameter of the electromagnet, and the droplet robot is prevented from occupying the same position;
By activating a plurality of electromagnets simultaneously, a plurality of droplet robots are independently controlled in parallel using a plurality of generated local magnetic fields, forming a predetermined movement pattern, wherein each droplet robot reaches a specified target position under the drive of the magnetic field.
In some alternative embodiments, the control manner of the driving module includes one or more of the following:
Single coil driving mode: in this manner, each ferrofluid droplet robot can selectively move in eight directions, i.e., up, down, left, right, up-left, down-left, up-right, and down-right, depending on the single solenoid position activated;
Double coil driving mode: by activating two adjacent electromagnetic coils simultaneously and applying current in the same direction, the generated magnetic field causes the droplet robot to split in the drag force in the opposite direction; in contrast, when two adjacent coils are electrified with current in opposite directions, a magnetic potential energy minimum point exists, and magnetic force generated by the coils points to the point, so that the two droplet robots collide and merge under the action of the magnetic force and the surface tension to form a stable strip shape;
programmable motion control: under the double-coil driving mode, the droplet robot is stretched into a strip shape firstly, then the activated coils are switched, the surface tension is utilized to prevent the droplet from being broken, and the continuous programmable movement of the droplet robot is realized;
Magnetic field direction and current control: the movement and the morphological change of the droplet robot are determined by the direction of the magnetic field applied by the electromagnetic coil and the direction of the current, and the complex control of the droplet robot is realized by precisely controlling the direction and the size of the current.
In some alternative embodiments, the ferrofluid includes a surfactant, a carrier fluid, and dispersed magnetic nanoparticles Fe 3O4, forming a colloidal suspension.
In some alternative embodiments, the robot detection-tracking-positioning module includes a CCD camera for acquiring real-time position information of the droplet robot; extracting the number, the outline and the center coordinates of the ferrofluid droplet robots through an image processing algorithm; the position coordinates of the ferrofluid droplet robot are tracked and updated in real time through a multi-target tracking algorithm.
In some alternative embodiments, the plurality of electromagnets are arranged in a regular array to form a square matrix.
The invention has the following beneficial effects:
The invention provides an innovative large-scale ferrofluid droplet robot cooperative control system, which realizes accurate control and intelligent cooperation of ferrofluid droplet robot groups and realizes remarkable technical breakthrough in the field of micro-nano robots. The system generates a distributed magnetic field by using a distributed magnetic field generation platform, and independently controlling the current magnitude and direction of each electromagnet by using a plurality of electromagnets arranged in an array and a current driving plate connected with the electromagnets, so that addressable operation and accurate group collaborative driving of a ferrofluid droplet robot group are realized. The system utilizes superparamagnetism and liquid properties of the ferrofluid droplet robot to enable the ferrofluid droplet robot to perform programmable reconstruction under the action of an external magnetic field, wherein the programmable reconstruction comprises separation, combination, movement and shape change, so that fine object manipulation is flexibly and efficiently completed. The system combines a vision-based multi-target detection-tracking-positioning method, and the real-time position information of each droplet robot is acquired by a robot detection-tracking-positioning module through a vision system, so that closed-loop feedback control is realized, and the control accuracy is further improved. The control module dynamically adjusts the distributed magnetic field according to the real-time position information of the robot so as to realize the coordinated movement of the droplet robot group. In addition, the system adopts multi-target tracking and multi-robot planning strategies based on conflict searching in a software layer, so that intelligent collaboration and collaborative planning of the droplet robot clusters are realized. The design not only solves the limitation of the traditional magnetic field driving platform in the aspect of multi-robot control, but also provides a new solution for intelligent cooperative control of the ferrofluid droplet robot, is particularly suitable for the areas which are difficult to reach or enter at present such as complex closed environments or minimally invasive medical operations, and has high adaptability and innovation. Through the cooperative control system, the operation capability and the application range of the ferrofluid droplet robot group are remarkably improved.
Other advantages of embodiments of the present invention are further described below.
Drawings
Fig. 1 is a block diagram of a cooperative control system for a large-scale ferrofluid droplet robot in accordance with an embodiment of the present invention.
Fig. 2 is a design diagram of an electromagnetic coil array according to an embodiment of the present invention.
Fig. 3 is a diagram of a driving manner of a ferrofluid droplet robot according to an embodiment of the present invention.
Fig. 4 is a closed-loop control diagram of a ferrofluid droplet robot in accordance with an embodiment of the present invention.
Fig. 5 is a schematic diagram of a ferrofluid droplet robot collaborative planning according to an embodiment of the invention.
Fig. 6 is a schematic diagram of a ferrofluid droplet robot pattern generation according to an embodiment of the invention.
Detailed Description
The following describes embodiments of the present invention in detail. It should be emphasized that the following description is merely exemplary in nature and is in no way intended to limit the scope of the invention or its applications.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. In addition, the connection may be for both a fixing action and a coupling or communication action.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing embodiments of the invention and to simplify the description, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless explicitly defined otherwise.
Referring to fig. 1 to 6, an embodiment of the present invention provides a cooperative control system of a large-scale ferrofluid droplet robot, comprising: the ferrofluid droplet robots have superparamagnetism and liquid properties, can generate an induced magnetic moment under the action of an external magnetic field, realize alignment with the direction of the external magnetic field, can minimize internal energy by changing shapes, and can receive magnetic force positively related to the volume of the ferrofluid droplet robots under the magnetic field gradient; the ability to have programmable reconfiguration, including separating, merging, and transforming shapes; the driving module comprises a plurality of electromagnets arranged in an array and a current driving plate connected with each electromagnet, wherein the current driving plate can independently control the magnitude and the direction of current to each electromagnet so as to generate a distributed magnetic field, and realize addressable operation and group cooperative driving of a plurality of ferrofluid droplet robots; wherein, the coil of each electromagnet can generate a local nonuniform gradient magnetic field to act on the nearby droplet robot; the control module is communicated with the current driving plate and is used for managing the operation of the whole cooperative control system, and the control module comprises a distributed magnetic field generated by a plurality of electromagnets in a synchronous control mode so as to realize accurate control and coordinated movement of the ferrofluid droplet robot group; the robot detection-tracking-positioning module (can be simply referred to as a vision module) is in communication connection with the control module, and captures real-time position information of each unit in the ferrofluid droplet robot group by utilizing a vision system (such as a CCD camera) to detect, track and position multiple targets of the ferrofluid droplet robot group so as to realize closed-loop feedback control; the control module adjusts a distributed magnetic field generated by an electromagnet array communicated with the current drive plate according to the real-time position information of each ferrofluid droplet robot provided by the robot detection-tracking-positioning module so as to accurately control the cooperative motion of the ferrofluid droplet robot group.
In some embodiments, the ferrofluid may include a surfactant, a carrier fluid, and dispersed magnetic nanoparticles Fe 3O4, forming a colloidal suspension. The invention is not limited to the specific composition of the ferrofluid.
Referring to fig. 2, 5-6, in some embodiments, the plurality of electromagnets are regularly arranged to form a square matrix.
In some embodiments, the robot detection-tracking-positioning module comprises a CCD camera for acquiring real-time position information of the droplet robot; extracting the number, the outline and the center coordinates of the ferrofluid droplet robots through an image processing algorithm; the position coordinates of the ferrofluid droplet robot are tracked and updated in real time through a multi-target tracking algorithm.
Referring to fig. 1, in some embodiments, the collaborative control system of a large-scale ferrofluid droplet robot further includes a motion planning module for generating predefined paths for a population of ferrofluid droplet robots that plan paths for robot formation under constraints based on starting and target positions of the population of ferrofluid droplet robots using a collision search based algorithm, and planning collision-free paths for robot formation based on the position of each robot.
Referring to fig. 3, in some embodiments, the control manner of the driving module includes one or more of the following: single coil driving mode: in this manner, each ferrofluid droplet robot can selectively move in eight directions, i.e., up, down, left, right, up-left, down-left, up-right, and down-right, depending on the single solenoid position activated; double coil driving mode: by activating two adjacent electromagnetic coils simultaneously and applying current in the same direction, the generated magnetic field causes the droplet robot to split in the drag force in the opposite direction; in contrast, when two adjacent coils are electrified with current in opposite directions, a magnetic potential energy minimum point exists, and magnetic force generated by the coils points to the point, so that the two droplet robots collide and merge under the action of the magnetic force and the surface tension to form a stable strip shape; programmable motion control: under the double-coil driving mode, the droplet robot is stretched into a strip shape firstly, then the activated coils are switched, the surface tension is utilized to prevent the droplet from being broken, and the continuous programmable movement of the droplet robot is realized; magnetic field direction and current control: the movement and the morphological change of the droplet robot are determined by the direction of the magnetic field applied by the electromagnetic coil and the direction of the current, and the complex control of the droplet robot is realized by precisely controlling the direction and the size of the current.
The ferrofluid droplet robot in the embodiment of the invention has both liquid characteristics and magnetism. By remotely controlling the external magnetic field in time and space, programmable reconstruction of the droplet robot, including separation, merging, movement, and transformation into different shapes, can be achieved to flexibly and efficiently accomplish manipulation of fine objects. In particular, the system of the embodiment of the invention realizes formation cooperation of the droplet robot, and can further improve the maneuvering task to a new level.
The cooperative control system of the large-scale ferrofluid droplet robot provided by the invention realizes intelligent cooperation of droplet robot groups. The electromagnetic coil array platform is built on the hardware level, so that the free control of the distributed magnetic field in time and space is realized, and a foundation is laid for driving the droplet robot; in the software layer, the position information of the robot is acquired in real time by adopting a multi-target tracking algorithm based on OpenCV, and the collaborative planning of the droplet robot cluster is realized by combining with a multi-robot planning strategy based on conflict searching. The system can solve the problem of multi-robot control faced by the traditional magnetic field driving platform, and provides a solution for intelligent cooperative control of the large-scale ferrofluid droplet robot.
A group cooperative control system for a large-scale ferrofluid droplet robot is provided with a distributed magnetic field generation platform, so that the addressable operation of the robot is realized; the closed-loop feedback control of the robot is realized by combining vision-based multi-target detection-tracking-positioning; and constructing a multi-robot motion planning strategy to realize intelligent collaboration of large-scale ferrofluid droplet robots.
The distributed magnetic field generation platform comprises an electromagnet array for generating a distributed magnetic field, robot positioning is performed through visual detection and tracking, and a multi-agent cooperative motion planning strategy is implemented. The whole system can comprise a robot driving module, a robot control module, a robot detection-tracking-positioning module and a robot motion planning module. The driving module is used for generating a desired time-varying magnetic field and driving the robot to move; the control module comprises a communication interactive computer and an embedded system and is used for managing the operation of the whole system; the vision module is used for acquiring the real-time position of the robot so as to activate the adjacent electromagnetic coils; the motion planning module is used for planning a collision-free path for the robot formation according to the position of each robot. In one example, the distributed magnetic field is generated by 144 electromagnets, each having a diameter of 9mm and a height of 10mm. The electromagnets are arranged in a 12 x 12 array with the dimensions of the entire working space being 108mm x 108mm. Each electromagnetic coil is independently connected to a power supply, and when current in different directions is supplied, attractive force or repulsive force can be generated as required, and a plurality of micro coils can be activated simultaneously, so that vector synthesis of magnetic fields is realized.
When a current is applied to the electromagnetic coil, a local magnetic field can be generated, and the magnitude and the effective range of the magnetic field are related to the magnitude of the current. The magnetic field generated by a single electromagnetic coil can be expressed as:
Wherein [ mu ] is the magnetic permeability of the electromagnet, N is the number of turns of the electromagnetic coil, I is the current passing through the electromagnetic coil, and r is the position vector of any point in the current element and the space. When the ferrofluid droplet robot is in a gradient field generated by a coil, deformation and controlled motion are generated due to the action of external magnetic force. By independently controlling the conduction of electromagnetic coils around the micro-robots, the independent driving of a plurality of robots in a two-dimensional plane can be realized.
The ferrofluid droplet robot has both liquid properties and magnetic properties, and when a water-based ferrofluid is mixed with an oil solution, a ferrofluid droplet is formed due to immiscibility and surface tension. By spatially and temporally programming the external magnetic field, reconfigurable large deformation control and coordinated movement of multiple ferrofluid droplet robots can be achieved. The droplet robot can have two driving modes, namely single-coil driving and double-coil driving. In the single-coil driving mode, a local magnetic field is generated by activating adjacent coils of the droplet robot, and the droplet robot is attracted to move to the center of the coils; in the dual coil drive mode, the droplet robot is first stretched into a strip shape by applying opposite currents to adjacent coils under the influence of a magnetic field, and the droplet robot is then caused to maintain a streamlined movement by changing the active coils.
In one embodiment, each electromagnetic coil may be energized with a current of up to 1A, ensuring that the coil is operating at rated power. The current is output by adopting a motor driving chip, one chip internally comprises two H-bridge circuits, the direction of the current is controlled by controlling the conduction of different bridge arms, and the magnitude of the current is regulated by adopting PWM.
The control module may include a computer and an embedded system. The computer communicates with the microcontroller through MODBUS protocol, and the microcontroller communicates with the current drive board through IIC bus, and only two wires are needed to realize the expandable control of the whole platform.
The robot detection-tracking-positioning module is used for updating the position of the droplet robot in real time and providing visual feedback for closed-loop control of the system. The tasks mainly comprise multi-target detection, multi-target tracking and multi-target positioning. The specific operation is as follows: firstly, acquiring first frame image information of a camera, then performing operations such as binarization, filtering and the like on the image, and extracting information of droplet robots in a working space, wherein the information comprises the number of the robots, and the outline and the center coordinate of each droplet robot; then, tracking the robot in real time through an OpenCV multi-target tracking algorithm and updating the position coordinates; and finally, returning the coordinate information of each robot in the working space for activating the corresponding electromagnetic coil to independently drive the droplet robot.
In some embodiments, the motion planning module is configured to plan a collision-free path for the droplet robot cluster, and implement droplet robot formation intelligent collaboration. The multi-agent path planning method based on conflict search comprises two search processes. The top-level search adds constraints to each robot, the bottom-level search plans a path for each robot under constraint conditions until collision-free paths meeting all constraints appear, and the algorithm ends.
The movement mode of the droplet robots is point-to-point discrete movement, in some embodiments, a grid map method is adopted to establish a simulation environment of a real working space, after path planning is completed, path points are mapped to the real working space again, and the droplet robots are formed to complete collaborative tasks according to the planned paths.
When static obstacles exist in the working space, static obstacle avoidance of multiple robots can be achieved by designing obstacle avoidance constraints and adding the constraints to the path planner. Firstly, position information of an obstacle is acquired, then a safe distance constraint condition is formulated, and finally, each effective path is ensured to be larger than a safe distance during bottom planning.
Examples
As shown in fig. 1, a cooperative control system of a ferrofluid droplet robot includes a motion planning module, a control module, a driving module, and a vision module. The motion planning module is used for generating a predefined path, and planning a collision-free path for the robot system under constraint conditions by using a multi-robot path planning algorithm based on collision search according to the starting position and the target position of each droplet robot. The algorithm is written in Python language, and embedded into the system through the upper computer, so that the droplet robots are guided to reach expected positions under the collision-free condition, and the collaborative planning of a plurality of droplet robots is realized. The control module comprises a computer and a microcontroller, the computer uses MODBUS protocol to communicate with the MCU through a serial port, the MCU communicates with the driving module through IIC protocol, and the control of 144 paths of current can be realized only by two wires, so that the corresponding electromagnetic coils are activated, a desired magnetic field is generated, and the ferrofluid droplet robot is driven. The driving module comprises a current driving plate and an electromagnetic coil array plate. The current driving plate consists of three parts, namely a PWM modulation unit, a current direction control unit and a voltage output unit. The PWM modulation unit is used for generating PWM signals and controlling the output voltage; the current direction control unit is used for adjusting the conduction of the H bridge arm and controlling the direction of the output current; the voltage output unit adopts TB6612FNG motor drive chip, and there are two H bridge circuits in every chip, can control the output of two-way electric current. Each current driving plate can output 16 paths of current, the maximum current of each path can reach 1A, and 9 current driving plates are required to output 144 paths of current, so that independent control of each electromagnetic coil is realized. 144 electromagnetic coils are embedded in the electromagnetic coil array plate and used for generating a distributed local magnetic field to serve as a working space. The vision module employs a fixed CCD camera placed above the workspace for acquiring positional information of the droplet robot in real time while positioning 144 electromagnetic coils to determine their relative positions for activating the corresponding coils for driving.
As shown in fig. 2, the electromagnetic coils are arranged in a 12×12 array, and comprise 144 electromagnetic coils, so that 144 distributed local magnetic fields can be generated simultaneously. Each electromagnetic coil had an outer diameter of 9mm, an inner diameter of 4mm, a height of 10mm, a wire diameter of 0.16mm, a number of turns of 1100 turns, and an iron core having a diameter of 4mm was included inside to enhance the generated magnetic field, and the total resistance of the coil was about 26.4 ohms. When a current of 0.5A is applied, a non-uniform gradient magnetic field of 30mT can be generated, sufficient to drive the ferrofluid droplet robot. In addition, a single Printed Circuit Board (PCB) is designed for connecting the electromagnetic coil array to the current drive circuit. The coils at different positions can be activated simultaneously, so that programmable addressing operation of a plurality of droplet robots is realized. For example, four robots are controlled to walk out of the SIGS path simultaneously. The parallel cooperation capability can greatly improve the working efficiency of tasks, meanwhile, the miniaturization of robots limits the development of individual intelligence, and the defect of individual intelligence can be overcome through the cluster intelligence of mutual cooperation among a plurality of micro robots.
As shown in fig. 3, the ferrofluid is a stable colloidal suspension formed by dispersing magnetic nanoparticles Fe 3O4 in a surfactant and carrier fluid. Due to their liquid nature, ferrofluids are enabled to undergo active deformations such as splitting, merging, etc. extreme behaviors. Meanwhile, the plastic composite material can be passively deformed and extruded through a narrow pore canal which is much smaller than the plastic composite material, and is particularly suitable for complex closed environments. When an external magnetic field is present, the ferrofluid droplet produces an induced magnetic moment that is aligned with the external magnetic field direction and minimizes the internal energy by changing shape. Under the influence of the magnetic field gradient, the magnetic droplet is subjected to a magnetic force proportional to its volume. Each electromagnetic coil is capable of generating a localized non-uniform gradient field that can drag a coil located adjacent to the droplet robot to the center of the coil when activated. As shown in fig. 3 (a) and (b), when the single coil driving mode is adopted, the droplet robot has 8 selectable movement directions, respectively, up, down, left, right, up left, down left, up right, and down right, depending on the position of the activation coil. Meanwhile, when two adjacent coils of the droplet robot are activated to generate a magnetic field in the same direction, the magnetic droplets are split due to drag forces in opposite directions, and can be polymerized by activating a coil in the middle of the two droplets, as shown in fig. 3 (c) and (d). In addition, when the current flowing directions of two adjacent coils are different, different movements can be generated by the liquid drops. As shown in fig. 3 (e) and (f), when two adjacent coils are supplied with current in the same direction, the magnetic droplets are split by receiving attractive magnetic force in opposite directions; when two adjacent coils are electrified with current in opposite directions, a magnetic potential energy minimum point exists in the situation, at the moment, the magnetic force generated by the coils points to the minimum point, and two magnetic liquid drops move, collide and combine under the action of the magnetic force and the surface tension to form a stable strip shape. Therefore, a dual-coil driving mode may be adopted, as shown in (g), (h) and (i) of fig. 3, the droplet robot is first changed into a strip shape under the action of the dual-coil magnetic field, and then the activated coils are switched, so that the magnetic droplet is not broken due to the existence of surface tension, and further programmable motion is generated.
As shown in fig. 4, a vision-based closed-loop feedback control method is employed. In order to activate the corresponding coils effectively, 144 coils need to be calibrated so as to determine the relative positions of the droplet robot and each coil. The camera firstly acquires the position information of the droplet robot, compares the position information with the expected position, calculates the required magnetic force according to the position error, converts the magnetic force into output current, and then acts on the magnetic field generation platform to drive the droplet robot to generate controlled motion.
As shown in fig. 5, parallel control of multiple droplet robots can be achieved with the designed distributed magnetron platform. Since the droplets exhibit superparamagnetism, they can be magnetized by an external magnetic field and have no magnetic force with respect to each other. Each electromagnetic coil can be considered a potential point of path. The path points may be given manually or may be generated automatically by a path planning algorithm. For example, a collision-free path is planned for four droplet robots by using a multi-robot path planning algorithm based on collision search, so that the position interchange of the four droplet robots is realized. Robot 1 and robot 4 interchange positions, robot 2 and robot 3 interchange positions, and their respective paths are represented by different types of line segments, respectively. Since the droplet robot has a waiting condition in the moving process, the droplet robot has 9 optional moving states in each planning step, and in order to avoid that the droplet robot occupies the same position, a distance constraint is required to be added, namely, the distance between the centers of the two robots is always larger than the diameter of the coil.
As shown in fig. 6, the magnetic control platform comprises 144 electromagnetic coils, and can theoretically generate 144 local magnetic fields, so that the cooperative control of the large-scale ferrofluid droplet robot can be realized. Here, an example of controlling 20 droplet robots simultaneously to form the tha formation is shown. As shown in fig. 6 (a), when 20 coils are simultaneously activated, the droplet robots are not aggregated with each other due to the magnetic force greater than the surface tension, but are independently distributed at the center positions of the coils. A target position is designated for each robot, and in combination with a path planning algorithm, the droplet robot finally reaches the position (b) of fig. 6 under the drive of the magnetic field generated by the corresponding coil, so as to form a target pattern.
In summary, the embodiment of the invention provides an innovative large-scale ferrofluid droplet robot cooperative control system, which realizes accurate control and intelligent cooperation of a ferrofluid droplet robot group through the design of a distributed magnetic field generation platform. The system utilizes a local nonuniform gradient magnetic field generated by the electromagnet array to realize addressable operation and accurate control of the droplet robot, allows the droplet robot to be independently driven in a two-dimensional plane, and performs closed-loop control according to multi-target detection-tracking-positioning real-time feedback. Furthermore, the multi-robot motion planning strategy based on conflict search realizes collaborative planning of the droplet robot clusters, solves the limitation of the traditional magnetic field driving platform in the aspect of multi-robot control, improves the working efficiency of tasks, and allows the robot population to adapt to complex and changeable task demands. The system provided by the invention not only can realize independent control of the droplet robots, but also can perform group cooperation through the motion planning module to generate collision-free paths, so that intelligent cooperation of formation is realized, and the system is particularly suitable for areas which are difficult to reach or enter at present, such as complex closed environments or minimally invasive medical operations.
The foregoing is a further detailed description of the invention in connection with specific/preferred embodiments, and it is not intended that the invention be limited to such description. It will be apparent to those skilled in the art that several alternatives or modifications can be made to the described embodiments without departing from the spirit of the invention, and these alternatives or modifications should be considered to be within the scope of the invention. In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Those skilled in the art may combine and combine the features of the different embodiments or examples described in this specification and of the different embodiments or examples without contradiction. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims.
Claims (10)
1. A cooperative control system for a large scale ferrofluid droplet robot, comprising:
The ferrofluid droplet robots have superparamagnetism and liquid properties, can generate an induced magnetic moment under the action of an external magnetic field, realize alignment with the direction of the external magnetic field, can minimize internal energy by changing shapes, and can receive magnetic force positively related to the volume of the ferrofluid droplet robots under the magnetic field gradient; the ability to have programmable reconfiguration, including separating, merging, and transforming shapes;
The driving module comprises a plurality of electromagnets arranged in an array and a current driving plate connected with each electromagnet, wherein the current driving plate can independently control the magnitude and the direction of current to each electromagnet so as to generate a distributed magnetic field, and realize addressable operation and group cooperative driving of a plurality of ferrofluid droplet robots; wherein, the coil of each electromagnet can generate a local nonuniform gradient magnetic field to act on the nearby droplet robot;
the control module is communicated with the current driving plate and is used for managing the operation of the whole cooperative control system, and the control module comprises a distributed magnetic field generated by a plurality of electromagnets in a synchronous control mode so as to realize accurate control and coordinated movement of the ferrofluid droplet robot group;
The robot detection-tracking-positioning module is in communication connection with the control module, and captures real-time position information of each unit in the ferrofluid droplet robot group by utilizing a vision system to detect, track and position multiple targets of the ferrofluid droplet robot group so as to realize closed loop feedback control; the control module adjusts a distributed magnetic field generated by an electromagnet array communicated with the current drive plate according to the real-time position information of each ferrofluid droplet robot provided by the robot detection-tracking-positioning module so as to accurately control the cooperative motion of the ferrofluid droplet robot group.
2. The large scale ferrofluid droplet robot cooperative control system of claim 1, further comprising a motion planning module for generating a predefined path for the population of ferrofluid droplet robots based on the starting and target positions of the population of ferrofluid droplet robots, using a collision search based algorithm to plan a collision-free path for the robot formation under constraints based on the position of each robot.
3. The collaborative control system of a large scale ferrofluid droplet robot of claim 2 wherein the motion planning module utilizes a multi-agent path planning method comprising a top-level search that adds constraints to each robot and a bottom-level search that plans a path for each robot under constraints until collision-free paths that satisfy all the constraints occur.
4. The cooperative control system of a large-scale ferrofluid droplet robot according to claim 2, wherein the motion planning module establishes a simulation environment of a real working space by using a grid map method, and maps the path points to the real working space again after path planning is completed for a discrete motion mode of the robot point to point, and the droplet robot is formed to complete a cooperative task according to the planned path.
5. The cooperative control system of a large scale ferrofluid droplet robot of claim 2, wherein the motion planning module further comprises a static obstacle avoidance strategy for path planning in the presence of static obstacles in the workspace, comprising:
an obstacle position information acquisition unit for detecting and acquiring position information of a static obstacle in the working space;
The safety distance constraint condition making unit is used for making safety distance constraint according to the position information of the obstacle, so as to ensure that the robot keeps a preset safety distance with the obstacle in the moving process;
The bottom layer planning unit is used for carrying out bottom layer searching under the constraint condition added by the top layer searching, planning a collision-free path avoiding the obstacle for each robot, and enabling each path to meet the safety distance constraint condition so as to realize the safety cooperation of multiple robots in the working environment with the static obstacle.
6. A co-control system for a large scale ferrofluid droplet robot as claimed in claim 2, wherein one or more of the following co-control strategies are employed:
planning a collision-free path for the droplet robots by using each electromagnet in the distributed magnetic field as a potential path point, wherein the motion of each droplet robot is driven by a local magnetic field generated by the independently controlled electromagnet;
Utilizing a multi-robot path planning algorithm based on conflict search to realize position interchange among droplet robots so as to adapt to path planning and task requirements;
In the motion process, a plurality of selectable motion states are provided for the droplet robot, and distance constraint is added, so that the distance between the centers of any two robots is ensured to be always larger than the diameter of the electromagnet, and the droplet robot is prevented from occupying the same position;
By activating a plurality of electromagnets simultaneously, a plurality of droplet robots are independently controlled in parallel using a plurality of generated local magnetic fields, forming a predetermined movement pattern, wherein each droplet robot reaches a specified target position under the drive of the magnetic field.
7. A co-control system for a large scale ferrofluid droplet robot as claimed in any one of claims 1 to 6, wherein the control means of the drive module comprises one or more of the following:
Single coil driving mode: in this manner, each ferrofluid droplet robot can selectively move in eight directions, i.e., up, down, left, right, up-left, down-left, up-right, and down-right, depending on the single solenoid position activated;
Double coil driving mode: by activating two adjacent electromagnetic coils simultaneously and applying current in the same direction, the generated magnetic field causes the droplet robot to split in the drag force in the opposite direction; in contrast, when two adjacent coils are electrified with current in opposite directions, a magnetic potential energy minimum point exists, and magnetic force generated by the coils points to the point, so that the two droplet robots collide and merge under the action of the magnetic force and the surface tension to form a stable strip shape;
programmable motion control: under the double-coil driving mode, the droplet robot is stretched into a strip shape firstly, then the activated coils are switched, the surface tension is utilized to prevent the droplet from being broken, and the continuous programmable movement of the droplet robot is realized;
Magnetic field direction and current control: the movement and the morphological change of the droplet robot are determined by the direction of the magnetic field applied by the electromagnetic coil and the direction of the current, and the complex control of the droplet robot is realized by precisely controlling the direction and the size of the current.
8. A synergistic control system for a large scale ferrofluid droplet robot as claimed in any one of claims 1 to 6, wherein the ferrofluid comprises surfactant, carrier fluid and dispersed magnetic nanoparticles Fe 3O4 forming a colloidal suspension.
9. A co-control system for a large scale ferrofluid droplet robot as claimed in any one of claims 1 to 6, wherein the robot detection-tracking-positioning module comprises a CCD camera for acquiring real-time positional information of the droplet robot; extracting the number, the outline and the center coordinates of the ferrofluid droplet robots through an image processing algorithm; the position coordinates of the ferrofluid droplet robot are tracked and updated in real time through a multi-target tracking algorithm.
10. A co-control system for a large scale ferrofluid droplet robot according to any one of claims 1 to 6, wherein the plurality of electromagnets are regularly arranged in a matrix.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410917484.XA CN118438459B (en) | 2024-07-10 | 2024-07-10 | Cooperative control system of large-scale ferrofluid droplet robot |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410917484.XA CN118438459B (en) | 2024-07-10 | 2024-07-10 | Cooperative control system of large-scale ferrofluid droplet robot |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN118438459A CN118438459A (en) | 2024-08-06 |
| CN118438459B true CN118438459B (en) | 2024-08-27 |
Family
ID=92320154
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410917484.XA Active CN118438459B (en) | 2024-07-10 | 2024-07-10 | Cooperative control system of large-scale ferrofluid droplet robot |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118438459B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118888249B (en) * | 2024-09-29 | 2024-11-29 | 清华大学深圳国际研究生院 | Global magnetic field generator for closed-loop control of spatial motion of multiple magnetic microrobots |
| CN119148602B (en) * | 2024-11-19 | 2025-02-07 | 清华大学深圳国际研究生院 | An autonomous navigation control system for a reconfigurable ferrofluid droplet robot |
| CN119257728B (en) * | 2024-12-11 | 2025-02-07 | 清华大学深圳国际研究生院 | Driving device and method for plane movement deformation of magnetorheological robot |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN205927916U (en) * | 2016-08-30 | 2017-02-08 | 中车株洲电机有限公司 | Lathe and clamping device thereof |
| KR20180000092A (en) * | 2016-06-22 | 2018-01-02 | 재단법인대구경북과학기술원 | Biomimetic system based on micro-organ and micorobot |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO342560B1 (en) * | 2016-11-15 | 2018-06-18 | Hans Gude Gudesen | Modular structures and method for construction thereof |
| US20220249817A1 (en) * | 2021-01-29 | 2022-08-11 | Ohio State Innovation Foundation | Microrobots with distributed actuation |
-
2024
- 2024-07-10 CN CN202410917484.XA patent/CN118438459B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180000092A (en) * | 2016-06-22 | 2018-01-02 | 재단법인대구경북과학기술원 | Biomimetic system based on micro-organ and micorobot |
| CN205927916U (en) * | 2016-08-30 | 2017-02-08 | 中车株洲电机有限公司 | Lathe and clamping device thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN118438459A (en) | 2024-08-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN118438459B (en) | Cooperative control system of large-scale ferrofluid droplet robot | |
| Xu et al. | Independent control strategy of multiple magnetic flexible millirobots for position control and path following | |
| Xu et al. | Multimodal locomotion control of needle-like microrobots assembled by ferromagnetic nanoparticles | |
| Donald et al. | Planar microassembly by parallel actuation of MEMS microrobots | |
| US8686602B2 (en) | Levitated micro-manipulator system | |
| Wang et al. | Selective and independent control of microrobots in a magnetic field: a review | |
| CN109857102B (en) | A wheeled robot formation and tracking control method based on relative position | |
| CN110270978B (en) | A micro-nano robot control platform system under the action of multi-physics energy field coupling | |
| Seon et al. | Automatic noncontact extraction and independent manipulation of magnetic particles using electromagnetic needle | |
| CN112991890A (en) | Translation type magnetic suspension system and float translation control method thereof | |
| Allwright et al. | Structure and markings as stimuli for autonomous construction | |
| Cui et al. | Novel coil array design and modeling for independent control of multiple magnetic microrobots | |
| CN109701894A (en) | A kind of robot system and control method of the restocking of books automatic sorting | |
| Das et al. | Simultaneous control of spherical microrobots using catalytic and magnetic actuation | |
| DE69900882T2 (en) | Constant current supply circuit for connectable module elements | |
| Işıtman et al. | Non-contact cooperative manipulation of magnetic microparticles using two robotic electromagnetic needles | |
| Fan et al. | Control of Multiple Identical Mobile Microrobots for Collaborative Tasks Using External Distributed Magnetic Fields | |
| CN1937391A (en) | Electromagnetic suspension and driving space micro motion method and mechanical device | |
| CN116594389A (en) | A Cooperative Control System of Magnetic Micro-robot Group | |
| KR102274949B1 (en) | Electromagnetic coil system having a triangular structure | |
| CN209502319U (en) | A kind of robot system of books automatic sorting restocking | |
| CN110474517B (en) | Rotor and suspension rotor motor | |
| CN119148602B (en) | An autonomous navigation control system for a reconfigurable ferrofluid droplet robot | |
| CN208627327U (en) | A kind of digital microcurrent-controlled chip report control platform | |
| Yang et al. | Automated control of multifunctional magnetic spores using fluorescence imaging for microrobotic cargo delivery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |