Nonlinear torque control of a single-link flexible robot

In this research, a nonlinear torque control law with a free function is applied to the simultaneous motion and vibration control of a single-link flexible robot. A rigorous proof of the asymptotic stability of the closed-loop system is provided and experiments are conducted by taking the free function in the feedback law as the output of one of the following vibration sensors: strain, shear force, reaction force, tip acceleration, and acceleration at some intermediate point. The experimental results demonstrate that the use of strain, shear force, and reaction force information in the control law can substantially suppress vibrations in the arm, while the effect of incorporating the acceleration information can be better or worse, depending on where the accelerometer is placed.