In the paper we aim to enhance the understanding of the effects of system properties, most notably the role of slave damping, on the performance of force reflecting teleoperators. Building on work by Daniel and McAree we argue that if a slave manipulator is critically damped then system performance, as measured by the maximum achievable force reflection ratio, becomes independent of the mass and stiffness of the operator. We give some experimental results in support of this.

This paper presents the analysis and characterisation of force controlled robotic drilling. We demonstrate that a robot manipulator can perform drilling if enough contact thrust-force is provided between a workpiece and drill, and is controlled properly. It is shown that the key parameters for robotic drilling are the drill rotational speed and thrust force. We believe that this implementation of a force control strategy on a robot manipulator for robotic drilling is unique; nobody has previously reported on the end point force control of a robot manipulator using a force/torque sensor for a drilling operation.>

An experimental comparison of model-based joint space position control (JSPC) and Cartesian space position control (CSPC) strategies for the same manipulator, trajectory, sample rate, and dynamic model is presented. It is shown that the achievable tracking performance (in terms of the peak tracking error) and disturbance rejection capability of JSPC was experimentally better than that of CSPC for the same sample rate. High feedback gains for CSPC were found to be unachievable, which the authors suggest is due to the incompatibility between actuation and control space. The effect of varying the trajectory velocity, and of using a diagonal or full mass matrix in the control torque computation on the performance of the both strategies is also presented.

Describes the development and experimental verification of a mathematical model for a force control system consisting of a PUMA 560 manipulator, force sensor, and environment. The main contribution is an argument that explicit dynamic models of manipulation systems used for force control are of little relevance or use. Identification techniques are used to model the system as a black box, measuring only an input/output relationship. The explicit dynamics of the mechanical, hardware, and software elements of the manipulator are neglected; they are considered as parts of the measured input/output relationship. P+D loops are closed around each joint of the manipulator before identification to reduce the uncertainties, to overcome nonlinearities, and thus to linearize the system. Close correspondence between the experimental and the simulated Bode plots for frequencies below 30 Hz indicates that the model developed accurate enough to be used to analyze and design a force control strategy for hard-on-hard contact applications, e.g., robotic drilling.

Proximity sensing and direct robot end effector position feedback are essential for real time sensor based control to enhance the perfor- mance of robot systems. The true values of the robot end velocity play a very important role in this task. Existing methods dealing with the prob- lem, however, are not valid or feasible under cer- tain conditions. A new measurement and filtering technique is proposed to derive the end velocity more reliably for a robot with highly uncertain vi- brational modes. The effectiveness of the approach is verified by both simulation and experiment.

An experimental and theoretical comparison is made of force control performance with different types of innerloop joint servoing techniques. The problem of disturbance rejection and sensitivity to plant dynamics variations (robustness) is addressed. Position, velocity, strain gauge derived joint torque, and current servos are designed and implemented on a specially instrumented industrial robot, and the end-effector force feedback performances achieved are compared. Joint strain derived torque servoing is found to provide the best overall robust force control performance. Experimental results of the robust hard-on-hard contact achieved with the novel force controller implementation based on joint torque sensing are provided. Conclusions are drawn on the force control performance achievable on a geared robot given the joint servoing technique.>

Guidelines are developed for the specification of input devices for use in teleoperation and related to the performance of systems where data are available. To date, little work has focused on such specifications, and this has made comparisons and evaluations of alternative solutions difficult. The general features of existing and potential designs are described, and their performance is analyzed in relation to previously generated specifications. The future of input device design is discussed.>

A tactile sensor has been developed which uses a layer of photoelastic material as its primary sensing element. This sensor has several desirable characteristics, including very high resolution, adaptable shape, and edge enhancement. Interestingly, the sensor has a similar sensing mechanism to human skin. A mathematical model has been developed for the sensor in an attempt to better understand its operation and to optimize its performance. The model draws heavily on the established fields of continuum mechanics and photoelastic stress analysis. The results of this analysis provide several important insights into tactile sensing and human touch, including an explanation of the importance of motion to touch, and the enhanced sensitivity of the sensor (and human skin) in detected edges.>