Disturbance-Observer-Based Dual-Position Feedback Controller for Precision Control of an Industrial Robot Arm

Recently, the fourth industrial revolution has accelerated application of multiple degrees-of-freedom (DOF) robot arms in various applications. However, it is difficult to utilize for precision motion control because their low stiffness. External loads applied induce deflections joints and links, which deteriorates positioning accuracy. To solve this problem, methods using a disturbance observer (DOB) with an external sensory system have been developed. sensors are expensive reliability noise reliance on surrounding environment. A disturbance-observer-based dual-position feedback (DOB-DPF) controller proposed herein improve accuracy by compensating real time only internal sensor. The DOB was designed derive unpredictable torque each joint command voltage generated position controller. angular deflection calculated based stiffness, were identified experimentally. DPF motor while simultaneously deflection. five-DOF arm testbed constructed verify contouring performance DOB-DPF compared that conventional load end effector. increases root mean square values contour errors 1.71 0.12 mm controller, respectively, after 2.2 kg weight results show error caused effectively compensated without