Optimized design and testing of a multi-degree-of-freedom cable-driven underactuated picking manipulator

In order to address the issues of poor flexibility and complex control systems in existing picking manipulators, the present work designs a multi-degree-of-freedom cable-driven underactuated manipulator. Firstly, an end-effector drive module based on the cam mechanism is designed, which can control gripping force without the need for force sensor feedback, and enables the opening, closing, and rotary movements of the end-effector to be controlled by the same motor. Secondly, the influence of the structural parameters of the fingers on the contact force at the phalange is analyzed, and then the end-effector is optimized using a genetic algorithm. Next, the cable pulling force control model is established. Subsequently, a prototype manipulator is fabricated for testing, the results show that the adjustment range of cable pulling force is 11.1–27.4 N, and the output torque of manipulator is 0.64 N·m. Finally, the results of picking test in the orchard demonstrate that the manipulator is capable of accomplishing non-destructive picking operations.