Extending Workspace of Robotic Container Unloading System via Additional Linear Axis

Robotic container unloading systems with significantly improved performance and enhanced sensing capabilities offer a genuine alternative to manual handling. Reachability limitation is one of the most significant scientific and technological challenges in the existing robotic systems for container unloading. This paper proposes a redundant robotic system with an additional linear axis to address reachability problems in container unloading scenarios. The kinematic analysis is derived based on the modified D-H parameters of the redundant collaborative robot. Afterwards, the working space of the redundant robotic system is simulated according to the Monte Carlo numerical analysis method. Extreme position grasping experiments are carried out using the proposed real-robot system to verify the simulation results. The experimental results show that the proposed robotic system is able to solve the inverse kinematics problem in container unloading, keeping all the joint angles within their respective physical limits. With the proposed design, an increase of 146.6% in the total workspace is achieved, which integrates the workspace of the fixed collaborative robot.