In this paper a new control strategy is introduced for tip trajectory tracking of flexible-joint manipulators driven by harmonic drives. The proposed controller incorporates friction compensating torque (FCT) and composite controller torque (CCT), which compensate for the friction in the harmonic drives and the flexibility of the joints, respectively. The FCT is a new controller which includes ...

Important robotic tasks could be most effectively done by powerful and accurate manipulators. However, high accuracy is generally unattainable in manipulators capable of producing high task forces due to such factors as high joint, actuator, and transmission friction and link elastic and geometric distortions. A method called Base Sensor Control (BSC) has been developed to compensate for nonlin...

In the current study, behavior of crank-slider mechanism with single and multiple clearance joints are analyzed. Using Lankarani-Nikravesh theory for estimating discontinuous contact forces in clearance joints, relevant systems have been mathematically modeled. Through numerical simulations, perturbations in response of mechanisms with clearance joints have been analyzed. Effects of increasing ...

12.7-mm thick plates of 6061-T6511 aluminum alloy and high hardness steel (528 HV) were successfully joined by a friction stir bonding process using a tungsten Process parameter variation experiments, which geometry, plunge and traverse rates, tool offset, spindle tilt, and rotation speed, were conducted to develop a parameter set which yielded a defect free joint. Laboratory tensile tests exhi...

Friction stir welding (FSW) is an emerging manufacturing technology for aerospace structures. It will see widespread use in the future as it offers ways of creating lighter structures at lower manufacturing cost than traditional methods (riveting, adhesive bonding). Since its invention in 1991, FSW has known fast improvements and many studies have demonstrated its capability for joining a wide ...

Stick-slip phenomenon is often associated with the control of low velocity motion because of the positional dependancy of friction and negative damping friction that decreases as the motion speed increases. In this paper, smooth low velocity tracking control of a commercial robot joint is demonstrated experimentally using a combination of high gain PID control, fast sampling rate and high posit...

The present approach for vibration suppression of flexible structures is based on friction damping in semi-active joints. At optimal locations conventional rigid connections of a large truss structure are replaced by semi-active friction joints. Two different concepts for the control of the normal forces in the friction interfaces are implemented. In the first approach each semi-active joint ha...

The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties o...

We present a new method of neural friction compensa tion in manipulator control especially during dynamic tasks with de ned contact to external environment Such manipulator movements involve internal joint friction and external friction between tool and environment The suggested method compensates friction caused dis turbances by means of neural networks Based on a minimal friction model Lyapun...