INTELLIGENT CONTROL OF TENDON-DRIVEN ROBOTIC MECHANISMS.

点击翻译按钮获取中文摘要

Tendon-driven mechanisms can be adjust the mechanical joint stiffness independently of the joint torques and robust for the stimulus disturbance forces. Therefore they are suitable for force-related tasks, while the control is very difficult due to the nonlinear elasticity. This project had two subprojects related to the feature. One of them is to develop intelligent controller for tendon-driven robotic mechanisms and the other is to develop a tendon-driven biped robot, to absorb the strong shock when the swing leg touches with the ground.For the intelligent control, we investigated (A) design stabilizing controllers for tendon-driven robotic mechanisms and (B) the optimization of the joint stiffness for given tasks. For (A), we developed ANN controllers composed of one adaptive module and two neural networks and proved the UBB of the desired force/position trajectories. For (B), we optimized the joint stiffness using GA for three tasks ; ball hitting, ball receiving, desired force tracking, and walking.We developed a tendon-driven biped robot. It has almost same size as a higher-class elementary school student. Each leg has 6 DOF and the knee joint and two ankle joints are driven with 6 tendons. Furthermore a newly designed nonlinear spring tensioning device (NST) is attached at the end of the tendons. This makes it possible to adjust the mechanical joint stiffness semi-actively and guarantees the robustness for the impulsive reaction forces from the ground. Other feature is the asymmetric joint torque allocation at the knee joint. Namely we used three tendons to expand the knee and only one tendon to bend it. The structure was designed using a commercial available structural analysis software. A FPGA-based control system was designed.GA was used to optimize the joint stiffness during walking. Simulation results showed this scheme would work well.