Cooperative force control of a hybrid cartesian parallel manipulator for bone slicing

Over the past two decades, robots have been increasingly used in biomedical applications such as bone cutting. Traditional automated manufacturing processes are often unable to meet the safety and accuracy requirements for such applications, particularly for cutting inhomogeneous constitutions of bone. In this case, human-robot cooperation may prove to be an effective approach. In this paper, we demonstrate that a hybrid parallel manipulator under cooperative force control can achieve accurate bone cutting with sufficient safety guaranteed. First, a hybrid parallel manipulator was constructed to provide the required rigidity for bone cutting. Then a two-loop controller was designed to implement the human-robot cooperation in bone cutting. The position control loop of adaptive fuzzy control is responsible for achieving high-tracking performance by overcoming varying friction forces from the mechanism. The force control loop of the cooperative force control adjusts the feed rate of the cutter according to the bone slicing conditions and operator's supervisory commands. The experimental results show that the proposed controller can effectively achieve the required accuracy in bone cutting with required safety.