CN119260704B - Multi-degree-of-freedom rope-driven discrete mechanical arm - Google Patents

Abstract

The invention discloses a multi-degree-of-freedom rope-driven discrete mechanical arm which consists of a rope-driven mechanical arm, a rack and a rear sliding table, wherein the rope-driven mechanical arm consists of a tail end mechanical arm, a tail end guide rod, a middle guide rod, a stretching reset spring, an angular contact bearing, a bearing cover, a universal joint, a shifting block, a sliding rod, a guide flat key, a compression reset spring and a guide rod seat assembly, and the rack consists of a rack body, a cradle mechanism, an electric sliding ring, a split wheel and a worm gear mechanism. The stepping motor on the frame is controlled to realize the circumferential rotation freedom degree of the cradle mechanism, the electric slip ring and the rope driving mechanical arm around the main shaft through the transmission of the worm and gear mechanism, the stepping motor on the cradle mechanism is used for adjusting the tension of two driving ropes through the transfer wheel to control the two shifting blocks to move on the sliding rod, the reset compression spring and the extension reset spring act together, and the sliding grooves on the shifting blocks are matched with the sliding grooves at the front and rear parts of the middle guide rod to provide the second to fifth rotation freedom degrees.

Description

Multi-degree-of-freedom rope-driven discrete mechanical arm

Technical Field

The invention relates to the field of robots, in particular to a multi-degree-of-freedom rope-driven discrete mechanical arm for complex space exploration and fetching, which provides a solution for realizing multi-freedom complex control by using fewer motors, can be matched with different components, realizes light-load grabbing, space exploration and other working tasks, and can be widely applied to industries of pipeline operation, post-disaster rescue equipment and the like.

Background

The emergency rescue after accidents and disasters has important significance ^[2] for reducing the loss of emergencies, and one major cause of most losses is that the situation in a complex cavity caused by earthquakes cannot be detected in time, but professional detection equipment is high in cost and complex in operation, and development of detection equipment which is based on advanced robot technology and is relatively cheap and easy to use is urgent. Therefore, the invention provides the multi-freedom wire-control discrete catheter mechanical arm controlled by a few motors, which can greatly reduce the high manufacturing cost and complex control caused by the plurality of motors, and the wire control system greatly improves the reliability and the maintainability of the equipment. The invention can reduce the cost in three aspects of hardware, software and operator training at the same time, thereby helping post-disaster rescue and engineering projects developed under the background of complex space such as pipeline operation.

In the design field of bionic robots, according to the actuation principle of linear driving, the design of a sliding block and a sliding groove is combined, so that the flexibility of the mechanical arm is greatly improved, the number of required motors is reduced, the working requirements are met, and meanwhile, the manufacturing difficulty and the manufacturing cost are reduced. In the prior chinese patent CN118061159a, an inflatable flexible manipulator is disclosed, which uses a rotary joint and a flexible joint to improve flexibility of the manipulator, wherein part of the structure uses a capstan and a thin wire to improve rigidity of the structure and realize a resetting operation. But this structural design is comparatively complicated, and the flexibility is limited, can't work in narrow and small space. In chinese patent CN117644501a, a foldable rope-traction parallel robot for smart operation in a narrow space is disclosed, in which a wire-driven mechanical arm at the end uses wire driving to have high flexibility and pliability, but compression springs are used as connection between joints, so that the precision is difficult to ensure, and the robot is difficult to work under the condition of loading. Chinese patent CN117415855A discloses a tendon-type rope-driven mechanical arm, which adopts a cross structure to improve the structural rigidity of the rope-driven mechanical arm, but at the same time, the flexibility is low and the four-motor control cost is high.

Disclosure of Invention

In order to solve the problems mentioned in the technical background, the invention aims to provide the mechanical arm with low cost, high flexibility and good rigidity, which can be widely applied to the fields such as post-disaster rescue, pipeline operation and the like.

The mechanical arm is composed of a front guide pipe system, a rack system and a rear sliding table system, wherein the front guide pipe system, the rack system and the rear sliding table system are connected through driving ropes and serve as carriers for power transmission.

The front mechanical arm is composed of a tail end guide rod, a middle guide rod, a shifting block, a universal joint, a base guide rod and the like, the shifting block is driven by a rope to move backwards during movement, the shifting block is clamped into a rear sliding groove in the guide rod, the universal joint limits the shifting block to rotate so as to shift the guide rod to rotate, and then the mechanical arm moves through inclined section planes at two ends of the guide rod. Similarly, when the tension of the string is reduced, the shifting block is reset by the compression spring and enters the front sliding groove, so that the guide rod further rotates, and the mechanical arm can continuously work. The middle guide rod and the tail guide rod can realize two degrees of freedom of rotation around the central point of the universal joint, and the two degrees of freedom of rotation can be controlled respectively by the split wheels.

Furthermore, the worm and gear mechanism drives the base guide rod to rotate, so that the degree of freedom of rotation of the mechanical arm around the main shaft is realized, and five degrees of freedom of the mechanical arm are intermittently controlled by two motors.

Furthermore, on the basis of the front mechanical arm, the rope driving mechanical arm is integrated and is arranged on the tail end guide rod, so that grabbing operation is realized, and meanwhile, the matched rear sliding table system provides power for the mechanical arm driving rope through the sliding table, so that grabbing action is realized.

The invention has the advantages that:

1. the invention provides a multi-degree-of-freedom rope-driven discrete mechanical arm, which has the advantages of low cost, high flexibility, good rigidity and the like. The whole adopts rope to drive, uses two motors to accomplish the five degrees of freedom control of arm, and a slip table realizes the snatching of manipulator, and cost and control cost are low.

2. The invention has good adaptability, is not limited to a single end effector of a manipulator, can be also adapted to other modules such as a camera, and can only be replaced by the end effector and a rear sliding table.

3. The invention has excellent flexibility, the five-degree-of-freedom mechanical arm can realize a nearly hemispherical reachable space, and the middle guide rod can further improve flexibility by increasing the number of units, so that the invention can be applied to complex working environments.

Drawings

Fig. 1 is a schematic view of a multi-degree-of-freedom rope-driven discrete mechanical arm according to the invention.

Fig. 2 is a cross-sectional view of a middle guide rod of a front mechanical arm of a multi-degree-of-freedom rope-driven discrete mechanical arm.

Fig. 3 is a schematic working diagram of a multi-degree-of-freedom rope-driven discrete mechanical arm rear slider.

Fig. 4 is a schematic working diagram of a multi-degree-of-freedom rope-driven discrete mechanical arm front slider according to the invention.

Fig. 5 is a top cross-sectional view of a multi-degree of freedom rope-driven discrete mechanical arm of the present invention.

Fig. 6 is a schematic diagram of a multi-degree-of-freedom rope-driven discrete mechanical arm end manipulator according to the invention.

Fig. 7 is a kinematic model of a multi-degree-of-freedom rope-driven discrete mechanical arm of the present invention.

Fig. 8 is a schematic representation of the achievable space of the invention with a single middle guide bar and three middle guide bars.

Fig. 9 is a schematic diagram of a motion state of a multi-degree-of-freedom rope-driven discrete mechanical arm according to the present invention.

Detailed Description

The present invention relates to the field of robots, and in order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description of the present invention will be given with reference to the accompanying drawings. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

The multi-degree-of-freedom rope-driven discrete mechanical arm comprises a front mechanical arm, a frame and a rear sliding table (shown in figure 1), wherein the front mechanical arm, the frame and the rear sliding table are connected through a driving rope and serve as a carrier for power transmission.

The front mechanical arm is composed of a tail end guide rod, a middle guide rod, a shifting block, a universal joint, a base guide rod and the like (figure 2), the shifting block is driven by a driving rope to move backwards when in movement (figure 5), the shifting block is clamped into a rear sliding groove in the guide rod, the shifting block is limited to rotate by the universal joint so as to drive the guide rod to rotate (figure 3), and the mechanical arm is moved by inclined section planes at two ends of the guide rod. Similarly, when the tension of the driving rope is reduced, the shifting block is reset by the compression spring and enters the front sliding groove (figure 4), so that the guide rod further rotates, and the mechanical arm can continuously work. The middle guide rod and the tail guide rod can realize two rotational degrees of freedom theta ₂、θ₃ and theta ₄、θ₅ around the central point of the universal joint, and the two degrees of freedom theta ₂、θ₃ and theta ₄、θ₅ can be controlled by the split wheels respectively.

Meanwhile, a worm and gear mechanism on the frame drives the base guide rod to rotate, so that the degree of freedom theta ₁ of the mechanical arm around the main shaft is realized, and five degrees of freedom (shown in figure 7) of the mechanical arm are intermittently controlled by two motors. On the basis of the front mechanical arm, a rope driving mechanical arm (figure 6) is integrated and is arranged on the tail end guide rod, so that grabbing operation is realized, and meanwhile, a matched rear sliding table system provides power for the mechanical arm driving rope through a sliding table, so that grabbing action is realized.

Examples

The multi-degree-of-freedom rope-driven discrete mechanical arm consists of a rope-driven mechanical arm, a rack and a rear sliding table, wherein the rope-driven mechanical arm, the rack and the rear sliding table are connected through a driving rope and serve as a carrier for power transmission.

The specific implementation process of the invention is as follows:

When it is desired to probe or retrieve objects in a complex pipe space, the present system is operated, with the first degree of rotational freedom of the front robotic arm (I) and cradle structure 2-14 being determined by the worm gear mechanism 2-16 via the stepper motor 1-1. And then the stepping motor 1-2 on the cradle structure 2-14 is controlled to rotate for a certain angle, the torque is increased through the gear set 5-4, the tension of the two driving ropes 5-2 is controlled by the dividing wheel 5-5, one end of each driving rope is fixed on the corresponding standard block 2-8 through the clip 5-1, the other end of each driving rope is fixed on the dividing wheel 5-4, and when the tension of the driving rope 5-2 is increased, the two shifting blocks 2-8 in the mechanical arm (I) move backwards along the sliding rod 2-9. When the shifting block 2-8 moves backwards for a certain stroke, the shifting block can be clamped into the rear chute 3-1 of the middle guide pipe, the middle guide rod 2-3 is driven to rotate and the mechanical arm (I) is driven to move under the constraint of the chute, and in the process, the extension springs 2-4 asymmetrically distributed around the guide pipe keep adjacent joints to be always contacted, so that the normal operation of the mechanical arm is maintained. When the tension of the driving rope 5-2 is reduced, the shifting block 2-8 moves forwards along the sliding rod 2-9 under the pushing action of the compression spring 2-11, and when the shifting block 2-8 moves forwards for a certain stroke, the shifting block can be clamped into the front sliding groove 4-1 of the middle guide pipe, and similarly, the middle guide rod 2-3 is driven to rotate and the mechanical arm (I) is driven to move under the constraint of the sliding groove, so that a rotating operation is completed. When the tail end manipulator 2-1 of the manipulator reaches a specified working position, the stepping motor 1-3 is operated, the sliding block 2-18 is driven to move backwards under the boosting action of the sliding table 2-17, three manipulator driving ropes 5-3 are fixed on the sliding block 2-18, and the other end of the three manipulator driving ropes is fixed on the fingers 6-3 on the tail end manipulator through the clips 6-2. When the tension of the manipulator driving rope 5-3 is increased, the fingers 6-3 are folded towards the center under the constraint of the wrist 6-4, and the friction pads 6-1 are arranged at the tail ends of the fingers 6-3, so that the friction force during grabbing can be increased, and the grabbing function is realized. When the articles are required to be placed and grabbed, only the stepping motor 1-3 is required to be operated to enable the sliding blocks 2-18 to move forwards, so that tension on the mechanical arm driving rope 5-3 is reduced, the reset torsion spring 6-5 resets the fingers 6-3, and release of the grabbed articles is achieved.

The included angle between the inclined cross sections of the two ends of the middle guide rod 2-3 and the axis is 25 degrees, and the two inclined cross sections of each joint are tightly attached to each other, so that 50-degree deflection with the axis can be realized. And because the worm gear 2-16, the electric slip ring 2-15 and the cradle structure 2-14 can support the whole rotation, the cradle structure is provided with the following functions:

θ₁∈[-180°,180°]

θ₂∈[-50°,50°]

θ₃∈[-50°,50°]

θ₄∈[-50°,50°]

θ₅∈[-50°,50°]

and the length of the connecting rod of the mechanical arm is a=67.5mm, and the accessible space of the mechanical arm with five degrees of freedom of two joints and nine degrees of freedom of four joints can be obtained by combining the data and the kinematic model (figure 8). The two-joint five-degree-of-freedom mechanical arm can achieve a space approximately in a half sphere shape, and the four-joint nine-degree-of-freedom mechanical arm can achieve a space approximately in a sphere shape, and the two mechanical arms have excellent flexibility. (FIG. 9)

The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.

Claims (4)

1. A multi-degree-of-freedom rope-driven discrete robotic arm, characterized in that: it consists of a rope-driven robotic arm, a frame, and a rear slide; the rope-driven robotic arm is located at the front of the frame, the end of the robotic arm is fixed to the frame, and the rear slide is fixed above the tail of the frame. The rope-driven robotic arm consists of an end effector, an end effector guide rod, a middle guide rod, a tension return spring, an angular contact bearing, a bearing cap, a universal joint, a lever, a slide rod, a guide key, a compression return spring, and a guide rod seat assembly. The guide rod seat is fixed to the frame, with a middle guide rod running through its center. The middle guide rod is connected to the slide rod via a universal joint. The middle guide rod is equipped with a guide key, a lever, and a compression return spring. The slide rod is fitted with either the middle guide rod or the end effector guide rod. The middle guide rod has an angular contact bearing and a bearing cap on its outer side. Tension return springs are asymmetrically arranged circumferentially on the bearing cap and connected to other guide rods. The end effector guide rod is mounted on the end effector guide rod as an actuator to perform grasping functions. The frame consists of a frame body, a cradle mechanism, an electric slip ring, a transfer wheel, and a worm gear mechanism. The cradle mechanism is mounted on the frame body and is coaxially mounted with the electric slip ring for easy signal transmission. The cradle mechanism is driven by a stepper motor mounted on the frame through a worm gear mechanism, enabling 360-degree rotation relative to the frame body. The cradle mechanism also has a stepper motor equipped with a transfer wheel to independently adjust the tension of the two drive ropes. The rear slide consists of a slide and a slider; the slider is fixedly mounted on the slide, and driven by the slide, the slider moves relative to the frame along the slide; the slider is also concentrically mounted with the aforementioned guide rod seat, cradle mechanism and electric slip ring. By controlling the stepper motor on the frame, the cradle mechanism, electric slip ring, and rope-driven robotic arm achieve circumferential rotational freedom around the main shaft through a worm gear mechanism, and possess precise control capabilities. The stepper motor mounted on the cradle mechanism uses a transfer wheel to adjust the tension of the two drive ropes, thereby controlling the movement of the two levers on the slide rod. The return compression spring and tension return spring work together to achieve the return function. The sliding groove on the lever cooperates with the sliding grooves at the front and rear of the central guide rod, providing the second to fifth rotational degrees of freedom. Finally, the tension of the robotic arm drive rope fixed to the end guide rod is adjusted by moving the slider back and forth on the slide table, achieving grasping control of the end robotic arm. 2. The multi-degree-of-freedom rope-driven discrete robotic arm according to claim 1, characterized in that the rope-driven robotic arm is driven by a drive rope to move a paddle, the paddle moving by engaging a sliding groove before and after the central guide rod; a slide rod and a return compression spring are provided on the axis of the guide rod, and tension return springs are asymmetrically distributed on the outer side of the guide rod, with the drive rope passing through the inside of the slide rod; a guide rod seat is fixedly installed on the frame, the central guide rod passes through the center of the guide rod seat, and the central guide rod is connected to the slide rod through a universal joint; a guide key, a paddle, and a compression return spring are installed on the central guide rod; the central guide rod or the end guide rod can be fitted onto the outside of the slide rod, and an angular contact bearing and a bearing cover are installed on the outer side of the central guide rod, with tension return springs asymmetrically arranged circumferentially on the bearing cover and connected to other guide rods; an end manipulator is equipped on the end guide rod as an actuator to realize the grasping function. 3. The multi-degree-of-freedom rope-driven discrete robotic arm according to claim 1, characterized in that a guide rod seat, a cradle mechanism, an electric slip ring, a worm gear, and a slider are coaxially mounted on the frame to provide positioning and support, and a stepper motor controller is integrated therein; the frame is provided with a dovetail groove; the cradle mechanism mounted on the frame is coaxially arranged with the electric slip ring to facilitate signal transmission; the cradle mechanism is driven by a stepper motor mounted on the frame via a worm gear mechanism to achieve 360-degree rotation relative to the frame; a stepper motor with a transfer wheel is also mounted on the cradle mechanism to independently adjust the tension of the two drive ropes. 4. The multi-degree-of-freedom rope-driven discrete robotic arm according to claim 1, characterized in that the slide is powered and controlled by a stepper motor, the slide amplifies the force output, enabling the slider to move back and forth along the slide, thereby affecting the tension of the robotic arm drive rope and realizing the grasping control of the end effector.