Abstract:
This thesis focuses on task specification and control for two cooperating
robot arms. A new task specification is designed to allow
a multi-robot system, in this case two cooperating industrial robots,
to perform a cooperative task in a coordinated manner. The coordinated
motion between the two robots is realized by feed forwarding
the velocity trajectories of the first robot to the second robot, or vice
versa. Unfortunately, this technique leads to a non-practical solution
of having to specify tasks for both robots.
Therefore, another task specification is introduced by exploiting
the redundant properties of the multi-robot system. This specification
is an extension of an existing task specification for a single robot
arm. Redundancy is used mostly for executing tasks which consist of a
relative motion between both robots. This method is straightforward,
since the programmer only has to fOCllS on the contact and relative motion
between the tool, held by one robot, and the manipulated object,
held by the other robot.
The utilization of redundant properties of the multi-robot system is
studied. Redundant manipulator theory is applied to both cooperating
robots so that during the task execution both robots stay within a
reachable and comfortable workspace, keeping them away from their
singular positions. Such an approach allows the multi-robot system to
perform a complete operation in one step; even difficult tasks can he
accomplished easily for which most single robot arms fail.
The above theory is demonstrated using simulation studies which
show very interesting results by utilizing redundancy of the multi-robot
system. Finally some experiments were performed using two industrial
robots, one of which was equipped with a six-dimensional force sensor. A comparison of some experimental results using a single robot
arm and two cooperating robot arms has been made and an effective
method for specifying the cooperative task based on redundancy is
proven.
