Position-Based Visual Servoing Control for Multi-Joint Hydraulic Manipulator

Manipulators are widely used in various fields of industrial automation, and hydraulic manipulators have more extensive application in future by virtue of high power to weight ratio. However, compared with the traditional motor manipulators, the dynamic model of hydraulic manipulator is more complex such as higher model order characteristics, which makes the design of precision motion controller of hydraulic manipulators more challenging. In addition, the application demand of hydraulic manipulator is gradually increasing even under various harsh conditions or extreme environments, which puts forward higher requirements for the autonomous environmental perception ability of hydraulic manipulators. Therefore, the visual servoing control for hydraulic manipulator is of great research value. In this paper, a position-based visual servoing control method for multi-joint hydraulic manipulator is proposed. To be specific, based on the obtained target position, the discrete desired path points can be got by velocity-limited path interpolation, which will be transformed into a discrete sequence of desired joint angles according to well-constrained inverse kinematics. Then the continuous desired angle trajectory of manipulator joint is generated by B-spline trajectory planner. Finally, the ideal angle trajectory is input into backstepping controller to contrive the angle tracking of each joint, so as to realize the visual target following control of multi-joint hydraulic manipulator.