Torque balance mechanism for cooperative mechanical arm of composite mobile robot

Abstract

The invention relates to the technical field of cooperation of composite mobile robots, in particular to a torque balance mechanism for a cooperative mechanical arm of a composite mobile robot. The spring energy storage mechanism is mounted on the cooperative mechanical arm main body part and is used for converting gravity torque into elastic potential energy so as to finish energy storage; the joint torque transmission mechanism releases the elastic potential energy, so that the elastic potential energy is converted into torque, part of gravitational potential energy generated by joint gravity is counteracted, and energy consumption of a joint motor is reduced; and the controller is arranged at the bottom end of the main body part of the cooperative mechanical arm and is used for actively compensating the joint torque by detecting the current of a joint motor so as to completely counteract the gravitational torque generated by the joint gravity. The method has good overall stability, a new variable named as the gravity deviation motor position is used for evaluating the gravity torque under each configuration, and the controller IV has higher flexibility in the aspect of proportional gain adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of composite mobile robot collaboration, and in particular to a torque balancing mechanism for a composite mobile robot collaboration mechanical arm. Background Art

[0002] Battery-powered composite mobile robot collaborative arms have achieved extensive development and commercial applications in many fields. However, with the increase of long-term high-load operation of collaborative arms, the problems of excessive joint torque and increased energy consumption have become particularly prominent. Therefore, the design of the gravity balance mechanism of the collaborative arm and its performance optimization have become a hot topic in the research field. This gravity balance mechanism is not only closely related to the dynamic balance and operational sensitivity of the dexterous arm, but also plays a key role in the integration of the dynamic characteristics of the entire collaborative arm and improving the stability and reliability of the arm in various working environments.

[0003] Traditional gravity balancing mechanisms usually use the counterweight method, which usually uses the joint motor as a counterweight to balance the gravity torque. This method greatly increases the total weight and inertia of the system, and increases the danger of the robot arm during operation. This method is more suitable for industrial robots with large self-weight, but for collaborative robots, the counterweight method is not an ideal choice. The defects of the counterweight method can be solved by the spring method. Domestic and foreign scholars have done a lot of research and application, using specific structures or motion / force transmission to convert the linear elastic force of the spring into nonlinear torque to counteract the gravity torque of the mechanism. Among them, the method of cleverly combining the spring and the four-bar mechanism is relatively mature, but the four-bar mechanism has a dead point, and there are safety hazards during the movement of the robot arm, and it is of limited help to the collaborative robot arm.

[0004] Application number 202111264031.4, the invention discloses a spring self-balancing robotic arm, whose structure includes: a robotic arm body, a first spring mechanism, a second spring mechanism, a second spring assist mechanism and a support seat. The invention uses a steel wire rope as a medium for torque transmission. The steel wire rope is relatively stiff and heavy, which will increase the inertial load of the robotic arm and limit its flexibility and range of motion. In addition, the steel wire rope is prone to wear and fatigue, and requires frequent maintenance and replacement, which increases costs and operational complexity. In addition, the joint activity angle of the robotic arm body of the invention is small, that is, the range of motion is small, and the universality is low. The compensation effect for the robotic arm with a large load is limited. If the joint rotation angle is too large, it may cause improper balancing of gravity. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a torque balancing mechanism for a composite mobile robot collaborative mechanical arm.

[0006] A torque balancing mechanism for a composite mobile robot collaborative mechanical arm, comprising:

[0007] The main part of the collaborative robot arm;

[0008] The spring energy storage machine is installed on the main part of the collaborative robot arm to convert the gravity torque into elastic potential energy, thereby completing energy storage;

[0009] Joint torque transmission releases elastic potential energy, which is then converted into torque, offsetting part of the gravitational potential energy generated by joint gravity and reducing the energy consumption of the joint motor;

[0010] Controller IV is arranged at the bottom of the main body of the collaborative robot arm. It actively compensates for the joint torque by detecting the joint motor current, thereby completely offsetting the gravity torque generated by the joint gravity.

[0011] Furthermore, the main body of the collaborative robot arm includes shoulder joint 1, shoulder joint 2, elbow joint, wrist joint 1, wrist joint 2, and wrist joint 3 connected in sequence.

[0012] Furthermore, the joint torque transmission mechanism III includes a tensioning base, a boom clamp arranged on the tensioning base by bolts, a bearing seat arranged on the tensioning base, a forearm synchronous pulley shaft arranged on the bearing seat, a stop ring arranged on the forearm synchronous pulley shaft, a wire drum matched with the forearm synchronous pulley shaft through the stop ring, a forearm synchronous pulley matched with the forearm synchronous pulley shaft, a boom synchronous pulley matched with the forearm synchronous pulley through a synchronous belt, and a boom flange coaxially rotated with the boom synchronous pulley, the boom flange is installed on shoulder joint two, the boom clamp is installed on shoulder joint one, the rope is wound on the wire drum, and the middle part of the rope is guided by the pulley.

[0013] The beneficial effects of the present invention are as follows: the present invention designs an adaptive PD controller with gravity compensation for the dexterous arm of a ground potential live working robot. The controller only requires motor measurement and has good global stability. A new variable, called gravity deviation motor position, is used to evaluate the gravity torque under each configuration. The controller has greater flexibility in adjusting the proportional gain. The present invention actively compensates for the joint torque by detecting the joint motor current, thereby completely offsetting the gravity torque generated by the joint gravity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0015] Figure 1 It is a schematic diagram of the main structure of the present invention;

[0016] Figure 2 It is a schematic diagram of the three-dimensional structure of the main part of the collaborative robot arm of the present invention;

[0017] Figure 3 It is a three-dimensional structural schematic diagram of the spring energy storage mechanism of the present invention;

[0018] Figure 4 It is a three-dimensional structural schematic diagram of the joint torque transmission mechanism of the present invention;

[0019] In the figure, 1-1, shoulder joint 1; 1-2, shoulder joint 2; 1-3, elbow joint; 1-4, wrist joint 1; 1-5, wrist joint 2; 1-6, wrist joint 3;

[0020] 2-1, guide rail; 2-2, upper bracket; 2-3, slider; 2-4, D-shaped buckle; 2-5, spring; 2-6, rope; 2-7, lower bracket 1; 2-8, pulley; 2-9, lower bracket 2; 2-10, forearm clamp; 2-11, bottom plate; 2-12, bushing; 2-13, forearm flange;

[0021] 3-1. Boom synchronous pulley; 3-2. Synchronous belt; 3-3. Bearing seat; 3-4. Forearm synchronous pulley shaft; 3-5. Stop ring; 3-6. Wire drum; 3-7. Tensioning base; 3-8. Boom clamp; 3-9. Forearm synchronous pulley; 3-10. Boom flange. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

[0023] like Figures 1 to 4 As shown, a torque balancing mechanism for a composite mobile robot collaborative mechanical arm comprises:

[0024] Collaborative robot arm main part Ⅰ;

[0025] The spring energy storage mechanism II is installed on the main part I of the collaborative robot arm, converting the gravity torque into elastic potential energy, thereby completing energy storage;

[0026] The joint torque transmission mechanism III releases the elastic potential energy and converts it into torque, offsetting part of the gravitational potential energy generated by the joint gravity and reducing the energy consumption of the joint motor;

[0027] Controller IV is arranged at the bottom of the main part I of the collaborative robot arm. It actively compensates for the joint torque by detecting the joint motor current, thereby completely offsetting the gravity torque generated by the joint gravity.

[0028] The collaborative robot arm main body part I includes a shoulder joint 1-1, a shoulder joint 1-2, an elbow joint 1-3, a wrist joint 1-4, a wrist joint 2 1-5, and a wrist joint 3 1-6 which are connected in sequence.

[0029] The main part I of the collaborative robot arm of the present invention is controlled by a controller IV, and the controller IV actively compensates for the gravity torque of the joint motor on the shoulder joint 2 1-2 by controlling the motor to output reverse torque.

[0030] The spring energy storage mechanism II and the joint torque transmission mechanism III are installed on the main part I of the collaborative robot arm. The rotation of the shoulder joint 1-2 drives the joint torque transmission mechanism III to transfer the joint torque to the spring energy storage mechanism II. This process realizes the conversion of gravity torque into elastic potential energy, thereby completing energy storage.

[0031] The spring energy storage mechanism II includes a base plate 2-11 and a slider 2-3 that can slide up and down relative to the base plate 2-11. A D-shaped buckle 2-4 is installed on the slider 2-3. The D-shaped buckle 2-4 is connected to a rope 2-6. When pulled by the rope 2-6, the slider 2-3 is driven to slide down and compress the spring 2-5 connected to the slider 2-3. The upper part of the base plate 2-11 is rotatably connected to a forearm flange 2-13 that cooperates with the elbow joint 1-3. The lower part of the base plate 2-11 is connected to a forearm clamp 2-10. The forearm clamp 2-10 is connected to a mechanical arm distributed between the shoulder joint 1-2 and the elbow joint 1-3.

[0032] The spring energy storage mechanism II also includes an upper bracket 2-2 and a lower bracket 2-7 installed on the bottom plate 2-11 and arranged in order from top to bottom. A guide rail 2-1 is installed between the upper bracket 2-2 and the lower bracket 2-7. The slider 2-3 is slidably fitted on the guide rail 2-1. The spring 2-5 is mounted on the guide rail 2-1 and one end is fitted with the slider 2-3 and the other end is against the lower bracket 2-7.

[0033] A lower bracket 2-9 is installed on the bottom plate 2-11, and a plurality of pulleys 2-8 for guiding the rope 2-6 are installed on the lower bracket 2-9, and the pulleys 2-8 are arranged vertically.

[0034] A shaft sleeve 2-12 is rotatably provided on the upper part of the base plate 2-11, and the forearm flange 2-13 is fixedly connected to the shaft sleeve 2-12.

[0035] The forearm clamp 2-10 and the lower bracket 2-7 are distributed on the opposite sides of the base plate 2-11.

[0036] When the joint returns to its initial state, the compressed spring 2-5 recovers, releasing the elastic potential energy, which is then converted into torque, offsetting part of the gravitational potential energy generated by the joint gravity, and reducing the energy consumption of the joint motor. The controller IV actively compensates for the joint torque by detecting the current of the joint motor, thereby completely offsetting the gravitational torque generated by the joint gravity.

[0037] The joint torque transmission mechanism III includes a tensioning base 3-7, a boom clamp 3-8 arranged on the tensioning base 3-7 by bolts, a bearing seat 3-3 arranged on the tensioning base 3-7, a forearm synchronous pulley shaft 3-4 arranged on the bearing seat 3-3, a stop ring 3-5 arranged on the forearm synchronous pulley shaft 3-4, a wire drum 3-6 matched with the forearm synchronous pulley shaft 3-4 through the stop ring 3-5, a forearm synchronous pulley 3-9 matched with the forearm synchronous pulley shaft 3-4, a boom synchronous pulley 3-1 matched with the forearm synchronous pulley 3-9 through a synchronous belt 3-2, and a boom flange 3-10 coaxially rotated with the boom synchronous pulley 3-1, the boom flange 3-10 is installed on the shoulder joint 2 1-2, the boom clamp 3-8 is installed on the shoulder joint 1-1, the rope 2-6 is wound on the wire drum 3-6, and the middle part of the rope 2-6 is guided by the pulley 2-8.

[0038] The controller IV includes a joint controller, and the controller IV is embedded in the manipulator. The controller IV of the present invention can achieve global regulation of the desired configuration quadrant drive motor qd through the PD control law, or use constant gravity compensation and sufficiently high position gain, or online evaluate the nonlinear gravity compensation term g under the current configuration.

[0039] The joint controller controls the movement of the shoulder joint 1-2, driving the upper arm flange 3-10 fixed thereon to rotate.

[0040] The upper arm synchronous pulley 3-1 drives the lower arm synchronous pulley 3-9 to rotate through the synchronous belt 3-2, and simultaneously drives the lower arm synchronous pulley shaft 3-4 to move, thereby driving the wire drum 3-6 to rotate.

[0041] The forearm synchronous pulley shaft 3-4 rotates with the forearm synchronous pulley 3-9, thereby driving the other side reel 3-6 to contract the rope 2-6. The rope 2-6 pulls the D-shaped buckle 2-4, driving the slider 2-3 to move downward along the guide rail 2-1. The slider 2-3 moves downward and compresses the spring 2-5, realizing the conversion of gravity torque into elastic potential energy.

[0042] The evaluation of the gravity term can only be avoided by using an additional saturated integral term. In the presence of joint elasticity, utilizing online gravity compensation is more complicated than in the rigid case. The gravity torque depends on the robot link positions, which in turn usually depend on the motor positions, which can be measured. On the other hand, PD control based on online gravity compensation of the motor positions G does not lead to the desired final balanced configuration.

[0043] Furthermore, the stability analysis is complicated by the mismatch between the available control torque on the motor side and the gravity torque to be compensated acting on the link side of the joint elasticity.

[0044] The present invention designs an adaptive PD controller with gravity compensation for a dexterous robot arm for live working at ground potential. This controller IV requires only motor measurements and has good global stability. The main idea is to use a new variable, named gravity deviation motor position, to evaluate the gravity torque at each configuration. A feature of this controller IV is that it has greater flexibility in the adjustment of the proportional gain, for example, in order to obtain better transients. In addition, the regulation scheme can be effectively combined with point-to-point interpolation trajectories to prevent motor saturation effects that usually occur in the first moment of movement when the robot joint position command changes stepwise. A control law is proposed that aims to adjust the robot link position to a desired constant configuration qd. The assumption is that the motor variables θ and θ are measurable, or at least, θ is measurable and θ is obtained by accurate numerical differentiation. The control law includes the proportional differential action rotation in the motor variable space, which starts the main part I of the collaborative robot arm to rotate, and the wire drum 3-6 makes a corresponding rotational motion. The wire drum 3-6 drives the forearm synchronous pulley shaft 3-4 to rotate through the round head flat key, and the rotation of the wire drum 3-6 will wrap around the rope 2-6 to synchronously drive the slider 2-3 to compress the spring 2-5.

[0045] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A torque balancing mechanism for a composite mobile robot collaborative manipulator, characterized in that: include: The main part of the collaborative robot arm (Ⅰ); The spring energy storage mechanism (II) is installed on the main part of the collaborative robot arm (I) to convert the gravity torque into elastic potential energy, thereby completing energy storage; The joint torque transmission mechanism (III) releases the elastic potential energy and converts it into torque, offsetting part of the gravitational potential energy generated by the joint gravity and reducing the energy consumption of the joint motor; The controller (IV) is arranged at the bottom of the main part (I) of the collaborative robot arm, and actively compensates the joint torque by detecting the joint motor current, thereby completely offsetting the gravity torque generated by the joint gravity.

2. The torque balancing mechanism for a composite mobile robot collaborative manipulator according to claim 1, characterized in that: The collaborative robot arm main body (I) includes shoulder joint one (1-1), shoulder joint two (1-2), elbow joint (1-3), wrist joint one (1-4), wrist joint two (1-5), and wrist joint three (1-6) connected in sequence.

3. The torque balancing mechanism for a composite mobile robot cooperative mechanical arm according to claim 2, characterized in that: The spring energy storage mechanism (II) comprises a base plate (2-11) and a slider (2-3) capable of sliding up and down relative to the base plate (2-11); a D-shaped buckle (2-4) is installed on the slider (2-3); the D-shaped buckle (2-4) is connected to a rope (2-6) and is pulled by the rope (2-6) to drive the slider (2-3) to slide down and compress a spring (2-5) connected to the slider (2-3); the upper part of the base plate (2-11) is rotatably connected to a forearm flange (2-13) matched with an elbow joint (1-3); the lower part of the base plate (2-11) is connected to a forearm clamp (2-10); and the forearm clamp (2-10) is connected to a mechanical arm distributed between the shoulder joint 2 (1-2) and the elbow joint (1-3).

4. The torque balancing mechanism for a composite mobile robot collaborative manipulator according to claim 3, characterized in that: The spring energy storage mechanism (II) further comprises an upper bracket (2-2) and a lower bracket (2-7) which are mounted on the bottom plate (2-11) and arranged in order from top to bottom. A guide rail (2-1) is mounted between the upper bracket (2-2) and the lower bracket (2-7). The slider (2-3) is slidably engaged with the guide rail (2-1). The spring (2-5) is sleeved on the guide rail (2-1) and one end of the spring is engaged with the slider (2-3) and the other end is abutted against the lower bracket (2-7).

5. The torque balancing mechanism for a composite mobile robot cooperative mechanical arm according to claim 3, characterized in that: A second lower bracket (2-9) is installed on the bottom plate (2-11), and a plurality of pulleys (2-8) for guiding the ropes (2-6) are installed on the second lower bracket (2-9).

6. The torque balancing mechanism for a composite mobile robot cooperative mechanical arm according to claim 3, characterized in that: A shaft sleeve (2-12) is rotatably arranged on the upper part of the base plate (2-11), and the forearm flange (2-13) is fixedly connected to the shaft sleeve (2-12).

7. The torque balancing mechanism for a composite mobile robot cooperative mechanical arm according to claim 4, characterized in that: The forearm clamp (2-10) and the lower bracket (2-7) are distributed on two opposite sides of the bottom plate (2-11).

8. The torque balancing mechanism for a composite mobile robot cooperative mechanical arm according to claim 3, characterized in that: The joint torque transmission mechanism (III) comprises a tensioning base (3-7), a large arm clamp (3-8) arranged on the tensioning base (3-7), a bearing seat (3-3) arranged on the tensioning base (3-7), a small arm synchronous belt pulley shaft (3-4) arranged on the bearing seat (3-3), a stop ring (3-5) arranged on the small arm synchronous belt pulley shaft (3-4), a wire drum (3-6) matched with the small arm synchronous belt pulley shaft (3-4) through the stop ring (3-5), and a small arm matched with the small arm synchronous belt pulley shaft (3-4). A synchronous pulley (3-9), a large arm synchronous pulley (3-1) matched with the small arm synchronous pulley (3-9) through a synchronous belt (3-2), and a large arm flange (3-10) coaxially rotatably matched with the large arm synchronous pulley (3-1), wherein the large arm flange (3-10) is mounted on the shoulder joint 2 (1-2), the large arm clamp (3-8) is mounted on the shoulder joint 1 (1-1), the rope (2-6) is wound on the drum (3-6), and the middle part of the rope (2-6) is guided by the pulley (2-8).

9. The torque balancing mechanism for a composite mobile robot collaborative manipulator according to claim 1, characterized in that: The controller (IV) includes a joint controller.

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