|Volume 22 Issue 5 - Publication Date: 1 May 2003
|Integrated Task Planning and
Control for Mobile Manipulators
|Jindong Tan Department
of Electrical and Computer Engineering, Michigan Technological University,
Houghton, MI 49931, USA , Ning Xi Department of Electrical
and Computer Engineering, Michigan State University, East Lansing, MI 48824,
USA and Yuechao Wang Shenyang Institute of Automation, Chinese
Academy of Science, Shenyang, China
|In this paper we present an
approach to decoupled force/position control of the end-effector along the
same direction for redundant robots, and an approach to nonholonomic cart
pushing with mobile manipulators. The mobile manipulator is considered as
a redundant robot, and a unified dynamic model for an integrated mobile
platform and on-board manipulator is developed. The dynamic model is decoupled
and linearized using the nonlinear feedback technique in a unified frame.
Combining the event-based planning and control method with singularity analysis
of the robot arm, a task level action controller is designed and an online
kinematic redundancy resolution scheme is developed. The system is stable
during normal operation as well as at the occurrence of unexpected obstacles.
In addition, explicit force/position control along the same task direction
for redundant robots is proposed. The kinematic redundancy of mobile manipulators
enables independent control of force and position along the same task directions.
To verify the decoupled force/postion scheme, an integrated task planning
and control approach is further proposed for the mobile manipulator to complete
complicated tasks by regulating its output force. A cart pushing task, which
requires both force and position control along the same task direction,
is discussed. The cart manipulation task fully integrates trajectory and
force planning of the cart, and planning and control of the mobile manipulators.
The approaches have been tested on a mobile manipulator consisting of a
Nomadic XR4000 and a Puma 560 robot arm. The experimental results demonstrate
the efficacy of the approach for the mobile manipulation of a nonholonomic