Industrial robots are widely used as flexible re-programmable positioning
devices in manufacturing plants, and allow to save costs, increase productivity
and raise quality. However, they still present capital intensive investments.
Therefore, increasing their autonomy and efficiency are topics of ongoing
research. With the increasing availability of cheap computation power and
low-cost sensors, considerable gains in efficiency and autonomy can be realized
through the use of additional sensors and sophisticated data processing and
control algorithms. This thesis focuses on two major research topics.
The first topic of this thesis deals with contact modeling and identification and
aims to advance the autonomy and intelligence of robots that interact with their
environment. To this end, robots are equipped with force sensors, in addition to
their built-in position sensors, to gather information about their environment.
To interpret measurements from these sensors, this thesis formulates and validates
contact models, which describe the behavior of robots in contact with their
environment. To characterize the interaction of robots with unstructured or
uncertain environments, this thesis also develops contact parameter identification
algorithms to identify the parameters of contact models. Based on the identified
contact parameters, the accuracy and robustness of the low-level control, as well
as the task execution can be improved on-line, while knowledge of the contact parameters
can be used off-line to design and validate constrained robotic tasks by means of
computer simulations.
The second topic of this thesis deals with optimal robot motion planning and
aims to advance the efficiency of robot motions. By optimizing robot motions,
while taking into account their dynamic behavior, robots can fully exploit
their capabilities and make full use of their actuators. This thesis develops
computer-aided algorithms for planning of robot motions along prescribed geometric
paths, called path tracking problems, with time as the main optimality criterion.
These path tracking algorithms allow to relieve operators from the burden of manual
optimization and tuning, and reduce the downtime of robots, while increasing
their productivity.