Showing papers by "Septimiu E. Salcudean published in 1993"

Motion scaling tele-operating system with force feedback suitable for microsurgery

Abstract: A robot suitable for micro-surgical application is formed by a robot arm having a position adjustable free end on which are mounted with their respective stators in fixed relationship a master and a slave robot. The position and actuation of the moving element of the master (master floater) and the moving element of the slave (slave floater) are used to couple their moment such that the master floater motion and forces are scaled down and followed by the slave and the slave floater motion and forces are scaled up and followed by the master. The sensed environment forces on the slave floater and sensed hand (environment) forces on the master can be used to improve the coordination between the master and the slave.

Velocity controller with force feedback stiffness control

Abstract: A force feedback velocity control measures the forces adjacent the end point of an arm being controlled and adjusts the stiffness of a manual controller in any one direction by scaling the end point force in the corresponding direction and adjusting the scaled force based on the degree of displacement of the manual controller away from a datum or zero velocity position in the one direction. A suitable deadband zone is provided surrounding the datum position.

Application of force feedback to heavy duty hydraulic machines

Abstract: The design and implementation of a force-reflecting controller for conventional heavy duty hydraulic machines are described. The unsuitability of direct force feedback with rate control has been shown analytically and confirmed on a simulator of a typical hydraulic machine. A stiffness control scheme to circumvent this problem was developed and used successfully in controlling the endpoint force on a CAT 215 log loader to better than 10% of a typical working load. A magnetically levitated wrist was used as a force-reflecting master, and the endpoint forces were obtained from hydraulic cylinder pressures. >

Precision assembly with a magnetically levitated wrist

Abstract: A magnetically levitated six-degree-of-freedom fine motion wrist design based on the prototype magic wrist described by R.H. Hollis et al. (1991) is introduced. Its use for automated assembly, where delicate accommodating motion and precise positioning is required, is discussed. The new wrist is smaller than the prototypes and has several improved features. Parts positioning and assembly strategies are discussed in general, with emphasis on the classic peg-in-hole problem. Results from insertion of a round peg into a close-fitting chamfered hole using the wrist programmed to emulate a remote center compliance are reported. It is found that higher insertion speeds can be maintained with much lower insertion forces and risks of wedging or jamming. >

A force-controlled pneumatic actuator for use in teleoperation masters

Abstract: A new pneumatic actuator for use in teleoperation masters and robot wrists requiring moderate, but accurate, force control is presented. The actuator uses flapper valves and low-friction cylinders. Its force is controlled by servoing differential pressure. Aspects of valve design, system modeling, controller design and experimental results are presented. A feedback controller is designed and implemented using a digital signal processor. For stationary loads, force control by pressure feedback is demonstrated with good frequency response and excellent repeatability. >

Coarse-Fine Motion Coordination and Control of a Teleoperation System with Magnetically Levitated Master and Wrist

Abstract: A novel teleoperation system was developed by equipping a conventional robot with a magnetically levitated fine-motion wrist and using an identical wrist as a master [1].

On-line controller tuning using the Q-parameterization

Abstract: This paper addresses the problem of tuning closed-loop controllers using online measurements. Numerical optimization of a controller in "internal model" form is performed by minimizing the performance functionals derived from specifications. By using measurements, not models, to evaluate performance functionals and their descent directions, computational savings and better actual performance are achieved. An example is used to demonstrate the tuning procedure and its usefulness. >

Development and performance of a three degree of freedom large motion vibration isolation mount for the KC-135 aircraft

Abstract: Scientific microgravity experiments conducted on platforms such as the Soviet Mir space station and the U.S. Space Shuttle indicated that the microgravity environment is contaminated with disturbances which result in the reduction of a gravity quality, from micro-g to milli-g. This paper describes the vibration isolation technology developed by the Canadian Space Agency, the 1DOF Large Motion Isolation Mount (LMIM) and the 3DOF LMIM, for the KC-135 aircraft. The results of the developmental activity are presented, and the applicability of the approach taken to the Space Shuttle, Space Station Freedom, and the Mir space station is discussed.