| Volume 26 Issue 1 - Publication Date: 1 January 2007 |
| Special Issue: The 12th International Symposium on Robotics
Research |
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| A Unified Passivity-based Control
Framework for Position, Torque and Impedance Control of Flexible Joint Robots
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| A. Albu-Schäffer, C.
Ott and G. Hirzinger Institute of Robotics and Mechatronics,
German Aerospace Center (DLR), Germany |
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| This paper describes a general
passivity-based framework for the control of flexible joint robots. Recent
results on torque, position, as well as impedance control of flexible joint
robots are summarized, and the relations between the individual contributions
are highlighted. It is shown that an inner torque feedback loop can be incorporated
into a passivity-based analysis by interpreting torque feedbackin terms
of shaping of the motor inertia. This result, which implicitly was already
included in earlier work on torque and position control, can also be used
for the design of impedance controllers. For impedance control, furthermore,
potential energy shaping is of special interest. It is shown how, based
only on the motor angles, a potential function can be designed whichsimultaneously
incorporates gravity compensation and a desired Cartesian stiffness relation
for the link angles. All the presented controllers were experimentally evaluated
on DLR lightweight robots and their performance and robustness shown with
respect to uncertain model parameters. Experimental results with position
controllers as well as an impact experiment are presented briefly, and an
overview ofseveral applications is given in which the controllers have been
applied. |
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| Multimedia Key |
= Video |
 = Data |
= Code |
= Image |
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Extension |
Type |
Description |
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Example
1: Cartesian impedance control is used for teaching and execution
of piston insertion. For comparison, the human execution is shown.
(2.5 MB) m1v |
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2 |
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Example
2: Table wiping with simultaneous null-space movement and force
control in vertical direction. (0.7 MB) m1v |
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3 |
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Example
3: Door opening using impedance control. (1.9 MB) m1v |
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4 |
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Example
4: Position control of the new humanoid system Justin. (1.4 MB)
m1v |
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5 |
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Example
5 : Crash test experiments for safety validation. (0.8 MB) m1v |
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