CN107756388B - A physical human-computer interaction platform based on rope traction and series elastic drive - Google Patents

Abstract

The invention relates to a physical man-machine interaction platform based on rope traction serial elastic driving. The device comprises a direct-current servo motor, a speed reducer, a coupler, a winch, a linear guide rail, a sliding block, a magnetic grating ruler, a spring, a handle, a rotating shaft and the like. The upper limb of a person drives the handle to move along the linear guide rail, and meanwhile, the direct-current servo motor provides corresponding driving force to drive the winch to pull the rope, so that the deformation of the elastic element is changed, and the effects of controlling the moment and the impedance of man-machine interaction are achieved. Through designing corresponding impedance controller, can realize safe, compliance, stable human-computer interaction.

Description

A physical human-computer interaction platform based on rope traction and series elastic drive

Technical field

The invention relates to a physical human-computer interaction platform based on rope traction and series elastic drive, which is generally used in the field of robots and rehabilitation medical equipment.

Background technique

With the development of robotics technology, robots increasingly need to physically interact with people or the external environment. When robots perform interactive tasks, safety is crucial. Traditional robots often use rigid drives to ensure fast response and high precision. If a failure occurs, it may pose a threat to the operator and the interactive environment. In order to improve the safety of the system, it can be achieved through two methods: active compliance and passive compliance of the robot.

In active compliance, the dynamic relationship between the force and displacement of the robot's end effector is adjusted by designing an impedance or admittance controller, that is, adjusting the size of the interactive impedance. For rigid drives, if a power outage occurs during the execution of a task and the impedance controller fails, it will still cause potential harm to people or the environment.

Series Elastic Actuator (SEA) has the advantages of strong compliance, low impedance, stable output, energy buffering and storage, resistance to external impact, and safety. It can achieve passive compliance of the system and improve the safety of the system.

The rope has the characteristics of light weight and single direction of force transmission. At the same time, when the force suddenly changes and exceeds the threshold, it will break, causing the transmission force to disappear, which plays a further protective role.

Contents of the invention

The invention provides a physical human-computer interaction platform based on rope traction and series elastic drive. The passive compliance of the system is improved through the series elastic driver, and the active compliance of the system is improved through impedance control. Combined with the rope traction, the stability of the system is improved. and security.

Technical solution of the present invention

An upper limb physical human-computer interaction platform based on rope traction and series elastic drive, including an aluminum alloy base plate. A linear slide rail and a magnetic strip parallel to the linear slide rail are installed on one side of the base plate. The linear slide rail is installed on There are three slide blocks, namely the first slide block, the second slide block and the third slide block. The three slide blocks are connected by two springs with the same elastic coefficient and length. The second slide block in the middle is fixed with The handle base and handle are used for human-computer interaction. A hook for fixing the rope is installed on the outside of the first slider and the third slider at both ends. A magnetic scale is installed on the sides of the three sliders. There are a total of 3 reading heads. The 3 magnetic scale reading heads and the magnetic strips cooperate to form a position measurement device, which is used to measure the positions of the three sliders in real time to obtain the deformation amount of the two springs. The elasticity of the springs is obtained through calculation. force; further obtain the position information and force conditions of the human hand; a U-shaped motor frame for fixing the motor and winch is installed on the other side of the base plate. A DC servo motor is fixedly installed on the outside of one end of the motor frame, and the motor shaft passes through After passing through the motor frame, it is fixed with the coupling. The other end of the coupling is connected to the winch. At the same time, the other end of the winch is connected and fixed with a screw rod. The screw rod passes through the screw hole at the other end of the U-shaped motor frame. The motor shaft The straight line is perpendicular to the linear slide rail; two ropes are wound in opposite directions on the winch, one end of the rope is fixed to the winch, and the other end of the rope passes through three rotation axes installed on the bottom plate between the motor frame and the linear slide rail. Connect and fix with the hook on the outside of the first slide block or the third slide block.

One end of the two ropes on the winch is fixed on the outside of the winch and wound in the middle in reverse direction. The take-out direction is one to the left and one to the right and is located on the same side of the winch so that the two ropes will not be rolled together during the rotation or Lateral deflection occurs. The ends of the two ropes are parallel to the linear slide rails.

The advantages and beneficial effects of the present invention are:

The invention uses a rope-traction series elastic driver, which has the advantages of strong compliance, low impedance, stable output, energy buffering and storage, resistance to external force impact, safety, etc., and can improve the compliance, safety and stability of the human-computer interaction system.

Description of drawings

Figure 1 is a schematic diagram of the mechanical structure of a physical human-computer interaction platform based on series elastic drive.

Figure 2 is a top view of the physical human-computer interaction platform based on series elastic drive.

Figure 3 is a schematic diagram of the mechanical structure of the motor frame and coupling.

Figure 4 is a side view of the motor frame.

Figure 5 shows the wire rope winding method.

Figure 6 is a schematic diagram of the human-computer interaction terminal.

Figure 7 is a schematic diagram of the wire rope connection method.

Figure 8 shows the axis of rotation.

Figure 9 is an impedance control block diagram.

In the picture, 1 DC servo motor, 2 motor frame, 3 coupling, 4 winch, 5 screw rod, 6 handle base, 7 first slider, 8 second slider, 9 third slider, 10 slide rail, 11 spring, 12 magnetic scale reading head, 13 magnetic strip, 14 hook, 15 wire rope, 16 handle, 17 base plate, 18 first rotation axis, 19 second rotation axis, 20 third rotation axis.

15 in Figures 1 and 2 shows the wire rope path.

Figure 5 shows how the wire rope is fixed and wound on the winch.

Detailed ways

The present invention will be described in more detail below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, the physical human-computer interaction platform based on rope traction series elastic drive includes an aluminum alloy base plate 17, and a U for fixing the servo motor 1 and the coupling 3 is installed at the upper position of the base plate. The aluminum alloy frame is called the motor frame here, that is, the motor frame 2. Servo motor 1 is fixed on the outside of one end of the motor frame through screws. After the motor shaft passes through the motor frame, it is fixed to the coupling through set screws. The other end of the coupling is connected to the winch 4, and the end of the winch is connected to a threaded screw rod 5 to form a whole. The screw rod 5 is installed on the other end of the motor frame through threads, as shown in Figures 3 and 4. The opposite side of the motor frame relative to the side of the fixed motor has a screw hole that matches the screw rod, and the screw rod passes through here.

The above-mentioned winch 4 is used to fix and drive two ropes, namely the steel wire rope 15. The winding method of the steel wire rope is as shown in Figure 5. This physical human-computer interaction platform uses a total of two steel wire ropes of the same length and 1 mm in diameter. There is a screw for fixing the wire rope on the outside of the winch (the upper and lower ends shown in the figure). Observe from the screw rod 5 to the motor side. After the wire ropes are fixed by the screws, the wire rope close to the motor side is reversed to the opposite side. Winding clockwise, the wire rope on the side close to the screw rod is wound clockwise to the opposite side (the winding directions of the two wire ropes can be interchanged). After the two steel wire ropes are wound for the same number of turns, they are taken out from the same side of the winch (the top in the picture) to both sides, one left and one right, so that the two ropes are parallel.

With the above structure and rope winding method, during the rotation of the motor, the wire ropes will not be rolled together or laterally deflected, thus avoiding the impact of changes in the rotation radius and lateral deflection on the elastic deformation of the spring.

A linear slide rail 10 and a magnetic strip 13 are installed at a lower position of the base plate perpendicularly to the straight line of the motor shaft. The linear slide rail is equipped with three two-row ball-type linear slide blocks with the same technical parameters, namely the first slide block 7, the second slide block 8 and the third slide block 9. There are two elastic coefficients in the middle of the three slide blocks. Connected to a spring 11 of the same length, as shown in Figure 6. A handle base 6 is fixed on the second slider 8 for fixing the handle 16. A hook 14 is fixed on the upper and outer sides of the first slider 7 and the third slider 9 for fixing the end of the wire rope 15. At the same time, a magnetic scale reading head 12 is fixed on the sides of the three sliders respectively (a total of 3 magnetic scale reading heads). The magnetic scale reading head and the magnetic strip cooperate to form a position measurement device for measuring the three slides. The position of the block is measured in real time to obtain the deformation of the two springs. The elastic force of the spring is calculated to further obtain the position information and force of the human hand.

The above two steel wire ropes are wound out after the winch is fixed, and are connected and fixed with the hook 14 on the first slide block 7 or the third slide block 9 through the first rotating shaft 18, the second rotating shaft 19 and the third rotating shaft 20 respectively. The ends of the two ropes are parallel to the linear slide rails, as shown in Figures 1 and 2.

The structure of the above-mentioned rotating shaft is shown in Figure 8 (the rotating shaft functions as an intermediate wheel and can be replaced by a pulley).

The power transmission process of the driver is: when the human hand drives the handle to move along the linear guide rail, the motor provides corresponding driving force, drives the winch to pull the rope, thereby changing the deformation amount of the elastic element, causing the interaction force and impedance perceived by the human hand to change. By designing the corresponding impedance controller, the desired softness of human-computer interaction can be achieved.

The block diagram of the impedance controller is shown in Figure 9, where: G _CSEA is the open-loop model of the rope-traction series elastic drive platform, and its inputs are the displacement of the handle. and motor speed control command ω _d , and the output is human-computer interaction torque τ _h . Z _d is the desired impedance model, and τ _d is the desired moment. e is the torque tracking error, and K is the impedance controller.

τ _h passes through the deformations of the two springs and according to the formula Ask for it.

in is the displacement of the motor end, and K _s is the equivalent stiffness of the two springs.

To sum up, the structural design of the present invention, based on the method of rope traction and series elastic driving, achieves flexible, safe and stable physical human-computer interaction.

Claims (4)

1. A physical human-computer interaction platform based on rope traction and series elastic drive, characterized by: the physical human-computer interaction platform includes a base plate, a linear slide rail and a linear slide rail parallel to the linear slide rail are installed on one side of the base plate. A magnetic strip, three slide blocks are installed on the linear slide rail, in order, the first slide block, the second slide block and the third slide block. The three slide blocks are connected by two springs. The second slide block in the middle A handle seat and a handle are fixed on the block for human-computer interaction. A hook for fixing the rope is installed on the outside of the first slide block and the third slide block at both ends; a hook is installed on each side of the three slide blocks. There are three magnetic scale reading heads in total. The three magnetic scale reading heads and the magnetic strips cooperate to form a position measurement device; a U-shaped motor frame for fixing the motor and winch is installed on the other side of the base plate. One end of the motor frame A DC servo motor is fixedly installed on the outside. The motor shaft passes through the motor frame and is fixed to the coupling. The other end of the coupling is connected to the winch. At the same time, the other end of the winch is connected and fixed with a screw rod. The screw rod is U-shaped. The screw hole at the other end of the motor frame is penetrated, and the straight line of the motor shaft is perpendicular to the linear slide rail; two ropes are wound in reverse on the winch, one end of the rope is fixed to the winch, and the other end of the rope passes through the motor frame and the linear slide rail respectively. The three rotation axes installed on the bottom plate between the rails are connected and fixed with hooks on the outside of the first slide block or the third slide block. 2. A physical human-computer interaction platform based on rope traction and series elastic drive according to claim 1, characterized in that: one end of the two ropes on the winch are respectively fixed on the outside of the winch and wound in the middle in reverse direction. , the take-out direction is one left and one right and located on the same side of the winch, so that the two ropes will not be rolled together or lateral offset during the rotation. 3. A physical human-computer interaction platform based on rope traction and series elastic drive according to claim 1 or 2, characterized in that: the ends of the two ropes drawn from the winch are parallel to the linear slide rails. 4. A physical human-computer interaction platform based on rope traction and series elastic drive according to claim 1 or 2, characterized in that the elastic coefficients and lengths of the two springs installed in the middle of the three sliders are the same.