Experiments on a Novel Hybrid Elastic Joint Robot with a Robust and Fast Control Strategy for Minimally Invasive Surgery

Document Type : Original Article


Center of Excellence on Soft Computing and Intelligent Information Processing, Department of Electrical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


Design and control of surgical robots for minimally invasive surgery have considerable challenges in handling unknown robot dynamics, environmental uncertainties, desirable workspaces, and fast motion reactions. Realistic operational requirements regarding kinematics and dynamics of the robot and its actuators also lead to joint elasticity; therefore, further concerns regarding sustained chattering, vibration, and instability are raised. Accordingly, the robot proposed here is designed based on a hybrid structure, consisting of two parallel and serial manipulators, aiming for the desired rigidity and acceptable manipulability requirements of robotic surgeries. Furthermore, a decentralized sliding mode controller with an indirect adaptive fuzzy estimator based on a voltage control strategy is employed to tackle the challenges of controlling such as chattering phenomenon, control loop's speed, and stability against uncertainties. In contrast to the traditional sliding mode controllers, the control law is free from robot dynamics, the control signals' chattering is reduced, and bounded input-bounded output stability is shown without knowing the uncertainty bounds on robot dynamics. Simulation and experimental studies indicate that this approach is realistic.