Balancing Control of a Mobile Manipulator with Two Wheels by an Acceleration-Based Disturbance Observer

Abstract

This paper presents the balancing control performance of a mobile manipulator built in the laboratory as a service robot called Korean robot worker (KOBOKER). The robot is designed and implemented with two wheels as a mobile base and two arms with six degrees-of-freedom each. Kinematics and dynamics of the robot are analyzed. For the balancing control performance, two wheels are controlled independently by the time-delayed control method based on the inertia model of the robot. The acceleration information obtained directly from the sensor is used for the modified disturbance observer structure called an acceleration-based disturbance observer (AbDOB). Experimental studies of the balancing control of the robot are conducted to compare the control performances by both a PID control method and an AbDOB.

Task-Oriented Generation of Stable Motions for Wheeled Inverted Pendulum Robots

“…As already mentioned, the pitch dynamics in a WIP robot is unstable. This is obviously true also for its linear approximation (9). To cope with this instability, we include in the QP formulation a constraint on the inputs in order to guarantee that the evolution of φ does not diverge 3 .…”

“…To extend this formulation, one can easily add state constraints by rewriting them as linear constraints on the decision variables by means of the prediction model (9).…”

“…It is possible for instance to model the platform as an inverted pendulum with the only goal of maintaining balance, and account for the manipulator motion as a disturbance to be compensated by the mobile base, e.g., via sliding mode control [8]. In [9] a PD control law has been used for balancing coupled with a PID controller for navigation while performance has been improved with a disturbance observer. Others, such as [10], propose a wholebody control law for balancing, which also allows the robot to gently interact with the environment.…”

Movements and Balance Control of a Wheel-Leg Robot Based on Uncertainty and Disturbance Estimation Method

“…From Equation (34), we can come to a conclusion that the control law consists of two parts: the first part is a feedback linearization(FL) controller, the second part is the uncertainty and disturbance estimation part. By comparing the proposed control law named FL-UDE in Equation (34) with FL in Equation (35), and the acceleration-based disturbance observer(AbDOB) [13] in Equation (36), the practical control performance of the designed controller is validated.…”

“…Motivated by the literature [13]- [16], the uncertainty and disturbance estimator(UDE) robust control has attracted the authors' attention with its strong robustness and excellent control performance. The UDE control method was proposed by Zhong Q C in [17] firstly with an assumption that a filter with the appropriate bandwidth can be used to estimated the engineering signal [18].…”