Friction-induced moments and subsequent cup loosening can be the reason for total hip joint replacement failure. The aim of this study was to measure the in vivo contact forces and friction moments during walking. Instrumented hip implants with Al2O3 ceramic head and an XPE inlay were used. In vivo measurements were taken 3 months post operatively in 8 subjects. The coefficient of friction was ...

A common architecture for torque controlled humanoid robots consists in two nested loops. The outer loop generates desired joint/motor torques, and the inner loop stabilises these desired values. In doing so, the inner loop usually compensates for joint friction phenomena, thus removing their inherent stabilising property that may be also beneficial for high level control objectives. This paper...

This paper addresses the motion control in joint space of robot manipulators with friction described by the generalized LuGre friction model. The paper extends the nonadaptive version of the Slotine and Li’s control system originally designed for friction-free manipulators to the case where a friction observer is incorporated to deal with friction. This observer corresponds to an adaptation of ...

This paper addresses the motion control in joint space of robot manipulators with friction described by the generalized LuGre friction model. The paper extends the nonadaptive version of the Slotine and Li’s control system originally designed for friction–free manipulators to the case where a friction observer is incorporated to deal with friction. This observer corresponds to an adaptation of ...

A general interface element is developed for dynamic response analysis of structures with jointed interfaces, which can account for damping due to both impact and friction. Contact effects are included through a segment-to-segment contact model which considers the stick-slip-slap behavior at every point along the joint interface. A nonlinear friction law is adopted at the interface to describe ...

This paper presents a robust tracking controller equipped with a fast friction estimator for a 6-DOF parallel electrical manipulator in the joint-task space. Parallel manipulator control scheme mainly stems from two frameworks: the task space control and the joint space control. The former requires the system states obtained via costly direct measurements or time-consuming forward kinematics. T...

A robust adaptive compensation scheme is presented for compensation of asymmetric deadzone, dynamic friction and uncertainty in the direct-drive robot manipulator. Simple estimation laws are derived to build observers for estimation of deadzone and friction based on the LuGre friction model. A model-free RWCMAC controller to mimic the ideal control law is employed to overcome some shortcomings ...

Few measurements have been made of the frictional forces within living joints. Barnett and Cobbold (1962) recorded that the coefficient of friction at the distal interphalangeal joint of the middle finger in six healthy adults could be as low as 0 0075, a figure of the same order as that in excised joints (Jones, 1936; Charnley, 1959). Rydell (1965) measured, in a patient fitted with a hip pros...

We present a unified treatment for modeling Coulomb and viscous friction within multi-rigid body simulation using the principle of maximum dissipation. This principle is used to build two different methods—an event-driven impulse-based method and a time stepping method—for modeling contact. The same principle is used to effect joint friction in articulated mechanisms. Experiments show that the ...