Current Research
Robotic Manipulator
Performance Analysis
In this work performance is studied in terms of a manipulator’s ability
to accelerate its end-effector, and to apply forces to the enviroment at the
end-effector. These abilities determine a robot’s capacity for manipulating
grasped and non-grasped objects. Acceleration capability also determines a
robot's quickness or responsiveness to controller commands. The thrust of
this work is to improve design methodologies for robots with large numbers
of degrees-of-freedom. The problem of designing for high performance becomes
much more difficult for these systems. The analysis is accomplished using
the system’s rigid-body equations of motion, which model the relationship
between end-effector accelerations and forces, and the system’s geometry,
mass, inertia, force transmission, and other factors. The goal here is to
develop analytical tools, which will allow for the design of robots with a
desired level of performance.
Flexibility
and Performance
Flexibilities in a robotic manipulator can reduce its acceleration capability
below what is predicted when the mechanism is assumed to be comprised of rigid
bodies. The intent here is to better understand the effects of flexibility
on performance. The goal of this work is the development of new design and
control practices, which yield high performance flexible systems.
Force Transmission
A key factor involved in obtaining the desired performance from a robot, is
generating sufficient amounts of force and moment from the actuation system.
The actuation system is comprised of motors/actuators, gears, tendons and
other components, which together supply the force required to move the mechanism.
This work investigates schemes for providing these required forces and moments,
while minimizing the mass and inertia of the actuation system, and increasing
the amount of force or moment attainable while the robot is moving at high
speeds.
This area considers locomotion produced by the movement of the various members of a robot. This includes walking rather than using wheeled vehicles, swimming rather than using propellers, and "flapping" rather than using jet or rocket engines. The focus here is more towards understanding agile motions, rather than the steady gait, walk or run. Football and soccer players exhibit the type of motion considered here. Agile swimming motions are also of interest. For instance, a fish can dart around extremely fast, quickly changing directions, even to the extreme of switching from forward to reverse motion in a split second. One application of this work is to improve a robot’s ability to avoid obstacles while moving at high speeds. This work could apply to planetary rovers, allowing them to quickly cover a lot of ground while avoiding obstacles in rough terrain. Studying agile motions involves examining the system’s equations of motion and the constraints imposed by the environment, which the mechanism pushes against to produce motion. The goal is to develop methodologies for design and control, which produce high performance locomotion systems capable of agile, high speed motions.
Selected Recent Publications
Bowling, Alan and Khatib, Oussama, "Actuator Selection for Desired Dynamic Performance" Proc. IEEE International Conference on Intelligent Robots and Systems (IROS '02),Lausanne, Switzerland, October 2002.
Bowling, Alan and Khatib, Oussama, "Robot Acceleration Capability: The Actuation Efficiency Measure." Proc. IEEE International Conference on Robotics and Automation (ICRA'00), San Francisco, California, April 2000, volume 4, pp. 3970-3975.
Bowling, Alan and Khatib, Oussama, "The Motion Isotropy Hypersurface: A Characterization of Acceleration Capability." Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS'98), Victoria, British Columbia, Canada, October 1998, volume 2 pp. 965-971.
Bowling, Alan and Khatib, Oussama, "Modular Redundant Manipulator Design for Dynamic Performance." Proc. Thirteenth CISM-IFToMM Symposium on Theory and Practice of Robots and Manipulators (Romansy13), Paris, France, July 1998.
Bowling, Alan and Khatib, Oussama, "Optimization of the Inertial and Acceleration Characteristics of Manipulators." Proc. IEEE International Conference on Robotics and Automation (ICRA'96), Minneapolis, Minnesota, April 1996, volume 4, pp. 2883-2889.
Direct comments, questions, and corrections to amedept@nd.edu