Intelligent Motion Control Design for an Omnidirectional Conveyor System

Nowadays, an omnidirectional conveyor system has been introduced as a new means of package transportation. The aim of this study is to achieve trajectory-tracking and collision avoidance of multiple packages which has not been done before on an omnidirectional conveyor platform. Despite the kinematic similarity to omnidirectional mobile robots which have built-in sensors to measure velocities and accelerations, this system only measures the position of the transported package via external sensors which makes it a unique and intriguing area of research. To tackle this challenge, this study employs the proposed Fuzzy Sliding-mode Tracking Control (FSTC) and Fuzzy Inter-package Collision Avoidance (FICA) schemes. The FSTC has been enhanced with fuzzy sliding surfaces that take tracking errors as control inputs and linear forces as control outputs. Furthermore, using a fuzzified package distance and collision angle as inputs, the inference engine of FICA is designed to generate the deflection angle and force gain as outputs. Additionally, the conveyor platform is modeled and built by a multiple modular omnidirectional wheel system including the conveyor and actuator dynamics. To determine its desired motion trajectory, a planned 4th-order Bèzier curve is utilized. Then, to assess the effectiveness and robustness of the proposed methods, simulations are conducted under diverse conditions. The results indicate that the package position converges within a finite time frame, highlighting the superior trajectory-tracking capabilities of FSTC in spite of any disturbances injected into position feedback signals. Meanwhile, the proposed FICA has demonstrated its effectiveness by enabling the package to navigate through the omnidirectional conveyor platform while avoiding both stationary and moving obstacles.