High-Precision Contour Tracking for Mobile Manipulators in Large-Scale Industrial Applications

Industrial manipulators are limited in their workspace due to mechanical constraints, which pose significant challenges in large-scale industrial applications. Expanding a robot's workspace often involves deploying additional stationary manipulators or integrating linear axes, both of which increase installation costs and system complexity without gaining much flexibility. A more effective and flexible solution is to integrate industrial manipulators onto mobile platforms. To support this research, the authors developed a mobile manipulator system consisting of a mobile platform driven by two Differential Drive Steering Units and an industrial robotic arm with six Degrees of Freedom (DoF). This configuration provides the system with nine DoF in its configuration space, substantially extending the workspace compared to conventional fixed-base manipulators. A trajectory control method is proposed to ensure smooth, low-vibration, and high-precision motion during operation. To enable accurate localization, a cost-effective method based on a 2D laser sensor and artificial landmarks is introduced. Furthermore, a high-precision contour tracking algorithm is developed to monitor the position of the end-effector relative to the workpiece. The proposed methods are validated through real-world experiments, demonstrating millimeter-level accuracy in both positioning and tracking.