| The friction between the contact surface of the sleeve and the flexible cable in the tendon-sheath transmission mechanism will cause gaps,hysteresis and dead zones in the transmission process,which is a difficult problem in the application of tendon-sheath transmission.Especially in the case of frequent commutation,it is difficult to achieve high-precision tracking control.Therefore,it is of great significance to study the hysteresis effect and compensation control of the tendon-sheath transmission mechanism applied to the mechanical arm transmission system.In this paper,a double-tendon-sheath-driven humanoid manipulator is taken as the research object.Based on the analysis of the single-tendon-sheath transmission characteristics,a control compensation scheme without output feedback is established,which effectively improves the transmission accuracy.At the same time,a double tendon-sheath transmission mechanism capable of installing an encoder is designed for the movement mode of the robot arm joint,and a compensation controller for real-time feedback is established.A seven-degree-of-freedom humanoid robotic arm prototype was developed based on the double-tendon-sheath transmission system,and its global performance indicators were analyzed based on the mechanical working space and the structure was optimized.Then the inverse solution of the seven-degree-of-freedom manipulator was solved,and a collision detection and response algorithm for the manipulator was established based on the tendon-sheath transmission model.The main research contents of the paper include:(1)The force transmission and displacement transmission models of a single tendon-sheath transmission system are established,and the simulation comparison between the static model and the dynamic model is performed to verify the correctness of the model.A single tendon-sheath transmission system experimental platform was set up,and the effects of the tendon-sheath’s transmission speed,friction factor,full curvature,and winding radius on its characteristics were analyzed.A friction compensation control algorithm without output feedback was established to improve the accuracy of the tendon-sheath drive system.(2)Although the offline compensation control method in a single tendon-sheath drive system does not require output feedback,it cannot adapt to the situation where the transmission characteristics change drastically in practical applications.During the movement of the humanoid manipulator driven by the tendon-sheath,the configuration of the tendon-sheath transmission system changes at any time,so a double tendon-sheath transmission system based on the real-time position feedback of the encoder on the articulated arm is designed.A double tendon-sheath transmission model suitable for any load is established,a semi-physical simulation experimental platform using a double tendon-sheath transmission system to drive a single articulated arm is established,and the correctness of the transfer model is verified through experiments.The feedback realizes the closed-loop feedback position control of the joint rotation angle,so that the output torque of the system can still follow the desired torque trajectory well when the external configuration environment is changed.(3)The structure and motion characteristics of the human arm and its joints are analyzed,and the structure design and optimization of the humanoid robotic arm driven by double tendon-sheath are realized.A forward kinematics model of a humanoid robotic arm was established and verified in MATLAB.The workspace of the robotic arm was obtained based on Monte Carlo method.Based on the workspace,the discrete performance index was selected to approximate the global performance index.,The dexterity of the robotic arm was evaluated,and the structure of the robotic arm was optimized,and the maximum error value of the end of the robotic arm in the working space was analyzed.Based on the Labview real-time development environment,a motion control interface for a humanoid robotic arm was set up.(4)Based on the method of restraining redundant degrees of freedom,the inverse solution of the manipulator is analyzed,and the inverse solution is verified by simulation.At the same time,a collision sensor was developed based on the single-tendon-sheath transmission system model,and the experiment of single-tendon-sheath-driven single-joint arm collision detection and response was completed. |
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