Soft Objects Grasping Control Based on External Torque Control Loops

To decrease the damage of grasping soft objects,an online joint torque predictive grasping control scheme is proposed based on external torque control loops.Grey prediction model is established to predict joint torque variation instead of stiffness of soft objects directly.The relations between joint torque deviation and angular velocity of manipulator are controlled.The predicted joint torque is gradually added to torque loops according to sampling period based on linear interpolation between the current torque and predictive one.Simulation results show that,when the stiffness of soft objects is variable,it makes grasping control system adaptive to the dynamic contact process between manipulator and soft objects,and can fast track fixed value without overshoots and oscillations.The control property and dynamic performance are greatly improved,so it is a good control method in grasping soft objects with strong robustness.