Model Predictive Control of Autonomous Delivery Robot with Non-minimum Phase Characteristic

Abstract

This paper introduces the concept of motion planning of delivery robot in an autonomous driving mode using an inverted pendulum model that can effectively control disturbance. The inverted pendulum model exhibits the non-minimum phase characteristic caused by the right half-plane zero. An effective method of reducing this characteristic is examined. A motion platform with 3-degree-of-freedom motion and a touch sensor are installed on a wheeled omnidirectional mobile platform. A steel ball is placed on the touch sensor and controlled to be located at the center. As the autonomous delivery robot moves, the steel ball is subjected to various disturbances and goes off the center. The influence of disturbance can be predicted by measuring the distance the steel ball moves away from the center. In this paper, linear quadratic regulator, preview control, and model predictive control are applied to the inverted pendulum model for motion planning, and thus the reduction of the non-minimum phase characteristic can be comparatively analyzed via simulation. The decrease in the disturbance is experimentally compared according to motion planning. Consequently, this paper proposes an effective motion planning method for an autonomous delivery robot with non-minimum phase characteristic.