6Axis Hybrid Sensing and Estimation of Tip ForcesTorques on a HyperRedundant Robotic Surgical Instrument In this paper a hybrid method for estimation of 6 degreeoffreedom (DOF) laparoscopic instrument tip forcetorques in roboticassisted minimally invasive surgery systems is proposed. The method is implemented on an inhouse developed hyperredundant (11DOF) surgical robotic forceps prototype. This surgical robot is composed of two modules with a 7DOF Kuka IIWA manipulator for performing 4DOF Remote Centre of Motion (RCM) about the trocar and an articulated 4DOF parallel wristgripper mechanism attached to the distal end of the Kuka robot for intracorporeal manipulation. The hybrid sensorbasedsensorless method fuses torque estimates from the parallel wrist mechanism with measurements from a force sensor attached between the wrist base and the Kuka tool frame. With this approach it is possible to obtain forcetorque estimates on all Cartesian axes (x, y, z, yaw, pitch, roll) of the forceps tip. The prototype is one of the first systems designed for robotic surgery that can achieve accurate force estimation on all 6 axes of the instrument tip. Experiment validation results with a force sensor verify the efficacy of the proposed method.

Sensorless Hybrid NormalForce Controller With Surface Prediction In this paper, an improved sensorless hybrid controller for constant force control along normal direction is proposed for applications including polishing, milling and deburring. No additional sensors are involved. External joint torques of all joints can be calculated from their electric current, dynamic model and friction model. With the help of dynamically consistent generalized inverse matrix, they can be converted to external forcetorque at the endeffector. The underlying force control strategy is the integration of impedance control model and explicit force control. The novel improvement is the realtime prediction algorithm of surfacexe2x80x99s shape profile and normal direction without any prior knowledge. So, this force controller has great adaptiveness to arbitrary unknown surfaces. Experiments were performed on a 7 degreesoffreedom (DOFs) robot to test the controllerxe2x80x99s capability and utility on an inclined plane and curved surface. Results prove the credibility of external force estimation. The normal force tracking accuracy is adequate for targeted applications. Realtime prediction is functional as the robot adjusts its orientation accordingly.