The authors investigate the Lyapunov stability property of a control scheme for the bilateral master-slave teleoperator, first introduced by the authors in 1990. Given the nominal models of the master and slave dynami...
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The authors investigate the Lyapunov stability property of a control scheme for the bilateral master-slave teleoperator, first introduced by the authors in 1990. Given the nominal models of the master and slave dynamics, and using an approximate feedback linearization control, based on the earlier work of M.W. Spong and M. Vidyasagar (1987), it is shown that Lyapunov stability can be obtained under the assumption that the deviation of the model from the true system satisfies certain norm inequalities. From these norm inequalities, it is shown that the tracking error (position/velocity and force/torque) is bounded and that sufficient conditions for Lyapunov stability can be achieved. The control scheme is illustrated using the simulation of a 30-degree-of-freedom master-slave teleoperator, and the results are presented.< >
A general algebraic framework for control analysis of constrained and compliant motion is presented. The author reviews the theory of screws, operators, and indefinite inner products to establish a mathematical formul...
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A general algebraic framework for control analysis of constrained and compliant motion is presented. The author reviews the theory of screws, operators, and indefinite inner products to establish a mathematical formulation for a task space decomposition suitable for synthesis of constrained and compliant motion. Four components of the space of screws are identified and their mathematical properties are presented. The proposed decomposition generalizes the original hybrid force and position control. Applications to contact kinematics and system dynamics are given for illustration. The main contribution is to shed light on the issue of the hybrid control assumption of presumed orthogonality between constraint and freedom subspaces.< >
This study deals with feedback control of system configuration drift resulting from the presence of the nonholonomic constraints, as compared to drift resulting from the kinematic redundancy of manipulators. The autho...
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This study deals with feedback control of system configuration drift resulting from the presence of the nonholonomic constraints, as compared to drift resulting from the kinematic redundancy of manipulators. The authors analyze the origins of this nonholonomic drift and formulate the problem to be solved to control it. They present an approach for globally optimal kinematic control of nonholonomic drift in robotic systems that is based on the utilization of task functions. The approach is applied to 3-D rolling manipulation systems to control nonholonomic drift of finger/object contact locations.< >
A systematic technique has been developed for synthesis of closed-loop dynamic controllers of motion in nonholonomic robotic systems. The proposed approach is based on the utilization of task functions for the synthes...
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A systematic technique has been developed for synthesis of closed-loop dynamic controllers of motion in nonholonomic robotic systems. The proposed approach is based on the utilization of task functions for the synthesis of joint velocity, acceleration, and torque commands. It has been shown that the resultant control methods are asymptotically stable in the case of tracking desired positions. The proposed control approach has also been applied to motion control in spacecraft/manipulator systems. The major application considered is a manipulator mounted on the spacecraft (no jets) in which nonholonomic constraints arise because of the nonintegrable angular momentum conservation law.< >
Several robust control schemes and a computed torque method were implemented on a two degree-of-freedom direct drive robot. Simulations and experiments have been performed to test the effectiveness of the control sche...
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Several robust control schemes and a computed torque method were implemented on a two degree-of-freedom direct drive robot. Simulations and experiments have been performed to test the effectiveness of the control schemes and to compare their performance. Based on the results obtained, an integral control has been introduced with a saturation control scheme. This has been found to generate a better tracking performance than the other methods evaluated experimentally. Some generic problems with the implementation of robust control schemes were found and are discussed.< >
The authors present the design, development, and implementation of a kinematic calibration procedure for robot manipulators working in coordination in a multiple robot facility. The objectives of this work were two-fo...
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The authors present the design, development, and implementation of a kinematic calibration procedure for robot manipulators working in coordination in a multiple robot facility. The objectives of this work were two-fold: (i) to identify the individual kinematic parameters of each robot, such as the link lengths, joint angles, etc., and (ii) to identify the global kinematic parameters of the multiple robot environment, such as the relative positions and orientations of the individual robot base frames. The identification required a multidimensional numerical root seeking procedure that behaved better than the traditionally used Newton-Raphson technique. A development of such a procedure (customized to the requirement of calibration) is outlined. The procedure was found to be extremely robust, as it handles the complexity of the model of five bar mechanism quite efficiently.< >
Extending the grasp compliance center concept to grasps in dynamic situations, previous work formulated a concept termed the grasp admittance center and showed that a grasp with an admittance center will have four dis...
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Extending the grasp compliance center concept to grasps in dynamic situations, previous work formulated a concept termed the grasp admittance center and showed that a grasp with an admittance center will have four distinct advantages: stability, decoupled force/motion relation, decoupled time response, and the ease of assigning the grasp dynamic behavior. The authors obtain the analytical conditions that must be satisfied for an admittance center to be achievable. They develop a procedure for computing the necessary fingertip impedances to achieve a desired admittance center. The results of experiments showing the regulation of the apparent impedances of a typical finger are presented.< >
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