Constraint-Following Servo Control for the Trajectory Tracking of Manipulator with Flexible Joints and Mismatched Uncertainty

Abstract

Trajectory tracking is a common application method for manipulators. However, the tracking performance is hard to improve if the manipulators contain flexible joints and mismatched uncertainty, especially when the trajectory is nonholonomic. On the basis of the Udwadia–Kalaba Fundamental Equation (UKFE), the prescribed position or velocity trajectories are creatively transformed into second-order standard differential form. The constraint force generated by the trajectories is obtained in closed form with the help of UKFE. Then, a high-order fractional type robust control with an embedded fictitious signal is proposed to achieve practical stability of the system, even if the mismatched uncertainty exists. Only the bound of uncertainty is indispensable, rather than the exact information. A leakage type of adaptive law is proposed to estimate such bound. By introducing a dead-zone, the control will be simplified when the specific parameter enters a certain area. Validity of the proposed controller is verified by numerical simulation with two-link flexible joint manipulator.

Real-Time Improvement of a Trajectory-Tracking Control Based on Super-Twisting Algorithm for a Quadrotor Aircraft

“…With the increasing use of robots in the fields of industry, rehabilitation, aviation, and marine exploration, the demand for robots that can adapt to complex environments and enable human-robot interaction is increasing, which introduces mission planning and trajectory tracking control on several applications related to robotics vehicles [5][6][7]. Besides, the author Mofid O., in collaboration with other colleagues, has published important information related to the tracking of Quadrotor helicopter trajectories, applying robust control techniques such as adaptive backstepping and sliding mode control to reduce external disturbances as well as uncertainties in the model, demonstrating stability and convergence in finite time, which guarantees adequate and correct tracking performance of the Quadrotor helicopter on the references provided for the fulfillment of a mission.…”