INTELLIGENT CONTROL OF TENDON-DRIVEN ROBOTIC MECHANISMS.

肌腱驱动机构能够独立于关节力矩调节关节刚度，对外界干扰力具有鲁棒性。因此，它们适合于与力相关的任务，而由于非线性弹性，控制非常困难。该项目有两个与该功能相关的子项目。其中一个是开发肌腱驱动机器人机构的智能控制器，另一个是开发肌腱驱动机器人，以吸收摆动腿与地面接触时的强烈冲击。在智能控制方面，我们研究了（A）设计肌腱驱动机器人机构的稳定控制器和（B）针对给定任务的关节刚度优化。对于（A），我们开发了由一个自适应模块和两个神经网络组成的ANN控制器，并证明了所需力/位置轨迹的UBB。对于（B），我们使用遗传算法优化了三个任务的关节刚度：击球，接球，期望的力跟踪和步行。它几乎和高年级的小学生一样大。每条腿有6个自由度，膝关节和两个踝关节由6个肌腱驱动。此外，一个新设计的非线性弹簧张拉装置（NST）连接在肌腱的末端。这使得可以半主动地调节机械接头刚度，并保证来自地面的脉冲反作用力的鲁棒性。另一个特征是膝关节处的不对称关节扭矩分配。也就是说，我们使用三个肌腱来扩展膝关节，只用一个肌腱来弯曲它。设计了基于FPGA的控制系统，采用遗传算法对步行过程中关节刚度进行优化。仿真结果表明，该方案能较好地实现目标。

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.