CHAPTER 7
Sensor Referenced Impact Control
in Robotics
RACHEL YUNYING WU
Computer Sciences Corporation, Fairview Heights, Illinois
TZYH-JONG TARN
Department of Systems Science and Mathematics, Washington University, St. Louis, Missouri
NING Xl
Department of Electrical & Computer Engineering, Michigan State University, East Lansing, Michigan
ALBERTO ISIDORI
Department of Systems Science and Mathematics, Washington University, St. Louis, Missouri
1 INTRODUCTION
This chapter addresses the issues of force regulating and contact transition stabilizing control
or so-called impact control. Impact control is required in most assembly tasks involving the
interaction of the manipulator and the workpiece. For workpieces with low tolerance, force
feedback is necessary to reduce the effect of the uncertain location and unknown stiffness of
the environment.
In a general contact operation, a certain approach velocity is needed for high productivity,
resulting in a collision with the contact surface. Collision is considered as a dangerous
phenomenon compromising the safety of the equipment.
In this chapter, we study a robust force control design via positive acceleration feedback
combined with a switching control strategy for the impact control and force regulation. The
transient force response during impact is controlled to limit the peak impact force. The
system can be stabilized after a finite number of switches. The output forces in the contact
directions and output positions in the moving directions can be regulated simultaneously
after contact is established. Accidental loss of contact can be corrected automatically. A great
amount of effort will be spent on the stability analysis, leading to a theoretical foundation in
the impact control area.
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