Volpe, R. and Khosla, P., A theoretical and Experimental Investigation of Impact control for Manipulators, International Journal of Robotics Research, Vol. 12, pp. 351-365, 1993  Home/Search   Document Details and Download   Summary   Related Articles   Check

....submitted for special issue Research on Autonomous Mobile Systems in Germany of the Journal on Robotics and Autonomous Systems to give this paper as a reference or to publish any part of this paper is not permitted 9 sensor information of the wrist sensors. In addition to former approaches [33] that are also based on the hybrid position force control of a two manipulator system [10] the new developed approach integrates also parameter scheduling. Depending on position of the arm (gravity) and requirements of the path, i.e. velocity or accuracy, different parameters are being chosen to ....

Volpe, R.; P. Khosla, P.: A Theoretical and Experimental Investigation of Impact Control for Manipulators. Int'l Journal of Robotics Research, 12, 4 (1993).

....detail the first part of this solution: experimental extraction of physical system model parameters. Elsewhere, we have used the parameters in the model to analyze the wide variety of force control strategies, and confirmed the analysis and model with experimental implementation of the strategies [11, 12]. Currently at The Jet Propulsion Laboratory (MS 198 219) California Institute of Technology, Pasadena, California 91109. Email: volpe telerobotics.jpl.nasa.gov) This work was completed while the author was a member of the Department of Physics, The Robotics Institute, Carnegie Mellon ....

....the real system response confirms the correctness of using the fourth order model, as well as the extracted parameter values. Third, the model has been used to analyze the efficacy and stability of many proposed force control strategies, and to understand the experimental results of tests of them [11, 12]. 8 Acknowledgements This research was performed at Carnegie Mellon University and supported by an Air Force Graduate Laboratory Fellowship (for Richard Volpe) DARPA under contract DAAA 21 89C 0001, the Department of Electrical and Computer Engineering, and The Robotics Institute. The writing ....

R. Volpe and P. Khosla. A Theoretical and Experimental Investigation of Impact Control for Manipulators. International Journal of Robotics Research, 12(4):351--365, August 1993.

....active control. It is the goal of impedance control to mask the intrinsic properties of the arm and replace them with the target impedance. The impedance relation can have any functional form. It has been shown that general impedances are useful for obstacle avoidance [Hogan (1985) Khatib (1986) Volpe and Khosla (1990)] However, it will be made clear in this section that sensor based, feedback controlled interaction with the environment is best achieved if the impedance is linear and of second order at most. This is for two reasons. First, the dynamics of a second order system are well understood and familiar. ....

....employed, as will be shown. 4. 2 Manipulator Model Based Control Manipulator model based control involves the use of a dynamic model of the manipulator to determine the actuation torques, Bejczy (1974) Model based impedance control may be summarized by the following equations [Hogan (1985) Volpe (1990)] D( m )u h( m ; m ) g( m ) J T ( m )f m (12) u = J Gamma1 ( m ) h x u Gamma J( m ) m i (13) x u = M Gamma1 [C Delta x K Deltax Gamma f m ] 14) Deltax = x c Gamma F( m ) 15) Delta x = x c Gamma J( m ) m : 16) Equation (12) compensates for ....

Volpe, R. and Khosla, P. 1993b (August). A Theoretical and Experimental Investigation of Impact Control for Manipulators. International Journal of Robotics Research, 12(4):351-- 365.

....gains Gamma1 K fp 1, is shown in Figure 7. In this figure the poles are shown at the beginning of the root locus, where K fp = Gamma1. Comparing Figures 7 and 5 it can be seen that negative gains provide a very stable system. Gains in this region have proven very effective for impact control [22, 26]. 3.2.2 Integral Control For integral control, H = K fi s , and L = 1 in Figure 4. A nonzero feedforward term, R, yields the following transfer function: F r Fm = R K fi s )G 1 K fi s G (9) Letting R be unity places a closed loop zero at s = GammaK fi which limits the ....

....presented. These include proportional control with feedforward, integral control, and proportional derivative control. All of these tests were conducted using the environment modelled previously. The contact problem was ignored to simplify these tests, but we have studied it extensively elsewhere [22, 26]. Finally, results are presented from tests conducted with the best of these controllers on a very stiff environment. 6 Explicit Force Control This section presents the results of implementing the explicit force control schemes discussed. All of these schemes were implemented in a Hybrid Control ....

R. Volpe and P. Khosla. A Theoretical and Experimental Investigation of Impact Control for Manipulators. In International Journal of Robotics Research, (accepted for publication in 1993).

....environment. The controller must, therefore, pass through the impact phase by attempting to maintain contact with the environment until all of the energy of impact has been absorbed. To maintain stability and contact during this phase, strategies for impact control will be reviewed in this section [65]. Previous research in force control has treated the impact phase as a transient that is dealt with by the same controller used to follow commanded force. The form of the force controller is typically an explicit force or impedance controller [70, 56] In this section it will be shown that the ....

....Integral force control acts as a low pass filter [76, 64, 55] Thus, for impact transients, the high frequency components are filtered effectively. For impacts with low energy or with an inelastic environment this may be sufficient [76] Otherwise, bouncing and possible instability will occur [65]. This is because of the nonlinear loss of contact with the surface and subsequent integrator wind up which cause severe hopping on the surface. Impedance Control and Proportional Explicit Force Control It has been analytically and experimentally demonstrated that impedance control against a ....

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R. Volpe and P. Khosla. A Theoretical and Experimental Investigation of Impact Control for Manipulators. International Journal of Robotics Research, 12(4):351--365, August 1993.

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Volpe, R. and Khosla, P., A theoretical and Experimental Investigation of Impact control for Manipulators, International Journal of Robotics Research, Vol. 12, pp. 351-365, 1993

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