A Theoretical and Experimental Investigation of Impact Control for Manipulators

Volpe, R.; Khosla, Pradeep K.

doi:10.1177/027836499301200403

Cited by 151 publications

(122 citation statements)

References 26 publications

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“…The control gains and , defined as scalars in (17) and (32), were implemented (with nonconsequential implications to the stability result) as diagonal gain matrices to provide more flexibility in the experiment. Specifically, the control gains were selected as (42) The adaptation gains were selected as (43) The adaptation gains in (43) are used to enable the adaptive estimate to be sufficiently changed relative to the large values of the uncertain parameters in due to the impact stiffness terms.…”

Section: A Experimentsmentioning

confidence: 99%

A force limiting adaptive controller for a robotic system undergoing a non-contact to contact transition

Liang

Bhasin

Dupree

et al. 2007

2007 46th IEEE Conference on Decision and Control

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Abstract-The problem of prescribing, reducing, or controlling the interaction forces between a robot and the environment during a noncontact-to-contact transition is intriguing because large interaction forces can damage both the robot and/or the environment or lead to degraded performance or instabilities. In this paper, we consider a two-link planar robotic arm that transitions from free motion to contact with an unactuated mass-spring system. The objective is to control a robot from a noncontact initial condition to a desired (in-contact) position so that the mass-spring system is regulated to a desired compressed state. The feedback elements for the controller in this paper are contained inside hyperbolic tangent functions as a means to limit the impact forces resulting from large initial conditions as the robot transitions from a noncontact to contact state. The main challenge of this work is that the use of saturated feedback does not allow some coupling terms to be canceled in the stability analysis, resulting in the need to develop state-dependent upper bounds that reduce the stability to a semiglobal result. New control development, closed-loop error systems, and Lyapunov-based stability analysis arguments are used to conclude the result. It is interesting to note that only the position and velocity terms are required for the proposed controller (i.e., the controller does not depend on measuring the impact force and the acceleration terms). Experimental results that successfully demonstrate the control objective are provided.

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Section: A Experimentsmentioning

confidence: 99%

A force limiting adaptive controller for a robotic system undergoing a non-contact to contact transition

Liang

Bhasin

Dupree

et al. 2007

2007 46th IEEE Conference on Decision and Control

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“…Figure 7 shows the proportional gain force control root locus for gains as low as negative one. We h a ve previously shown the utility of negative gains for impact control Volpe and Khosla 1993b . Other researchers have also discussed the use of negative gains, but usually within the context of impedance control Hamilton 1988, Hogan 1987 .…”

Section: Proportional Gain Explicit Force Controlmentioning

confidence: 99%

“…The brass weight serves as an end e ector substitute and provides a at sti surface for applying forces on the environment. More details can be found in Volpe andKhosla 1994a, V olpe andKhosla 1993b . This system is more complex than might rst be thought. Since the arm is not attached to the surface, oscillations can easily lead to separation from the surface.…”

Section: Arm Sensor Environment Modelmentioning

confidence: 99%

The Equivalence of Second-Order Impedance Control and Proportional Gain Explicit Force Control

Volpe

Khosla

1995

The International Journal of Robotics Research

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This paper discusses the essential equivalence o f s e cond order impedance c ontrol with force f e edback and proportional gain explicit force c ontrol with force f e edforward. This is rst done analytically by reviewing each control method and showing how they mathematically correspond for constrained manipulator control. For sti environments the correspondence is exact. However, even for softer environments similar response of the system is indicated. Next, the results of an implementation of these control schemes on the CMU DD Arm II are p r esented, con rming the predictions of the analysis. These results experimentally demonstrate that proportional gain force c ontrol and impedance control, with and without dynamics compensation, have equivalent response to commanded force t r ajectories.

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“…In the early 90's, the optimum approach velocity for force-controlled contact has been enthusiastically studied (Nagata et al, 1990, Kitagaki & Uchiyama, 1992). Volpe and Khosla proposed an impact control scheme for stable hard-on-hard contact of a robot arm with an environment (Volpe & Khosla, 1993). Mills and Lokhorst proposed a discontinuous control approach for the tasks that require robot arms to make a transition from non-contact motion to contact motion, and from contact motion to non-contact motion (Mills & Lokhorst, 1993).…”

Section: Introductionmentioning

confidence: 99%