Observer based nonlinear control using barrier Lyapunov function for position tracking of Sawyer motor under yaw constraint

In this paper, we present an observer based nonlinear controller using barrier Lyapunov function (BLF) for position tracking of Sawyer motor under yaw constraint. The dynamics of Sawyer motor is modified to apply BLF-based backstepping control design. To relax the matching condition, torque and force modulations are proposed. The modulations enable decoupling forces and torque of the Sawyer motor, and facilitate implementing the design of backstepping controller with the BLF. In addition, we propose a state augmented nonlinear observer to estimate the velocities, yaw rate, load forces and load torque. We show the closed-loop stability with a composite Lyapunov function. Simulation results validate the effectiveness of the proposed method.