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To be agile and efficient, robots–like humans and other biological machines–must operate in a dynamic regime; that is, where inertial forces and often elastic effects are significant. While robots–especially mobile robots–have been treated largely as quasistatic machines, my interest is in the dynamic effects that enable high performance, and possibly new and interesting behaviors.
I am currently involved in a number of research areas that reflect these interests:
Gyrover is a novel concept we are developing for a single-wheel robot that uses an on-board gyroscope for mechanical stabilization and steering control. Gyrover behaves much like a wheel rolling freely down a hill, but has the ability to steer itself, and stand in place. It can travel at high speed, and has good stability on rough terrain. The large rolling diameter and single track provide good obstacle avoidance and climbing, and minimize sensitivity to attitude disturbances. A third-generation Gyrover (7 kg., 40 cm diameter) is now in operation, and we are developing a control system for low-level functions using on-board computing and sensing.
Legged locomotion: While legged robots have long held promise for mobility greater than wheeled or tracked vehicles, most implementations have been complex, fragile and inefficient. We are addressing these issues with the development of a new elastic leg concept that is simple, lightweight, rugged and efficient. The leg can store elastic energy adequate for vertical jumps of a several meters, and can return about 80% or the energy from one step to the next. The concept is being tested on a 3 kg. planar hopping machine that can operate for 30 minutes on a small battery pack. Beyond the present planning and control work aimed at tasks such as negotiating randomly placed stepping stones and jumping over large obstacles, we plan to develop a self-contained, 3D version that uses human supervision for effective and efficient locomotion over real-world terrains.
Millibots are small semi-autonomous and autonomous robots to be deployed by a larger robot or field agent. Current Millibot modules include processing units, motor controllers, sensors, pan/tilt platforms, RF link transceivers. My particular interest is in developing trains of Millibots that can travel over very rugged terrain, then split up to perform their individual tasks. Challenges include small, high-torque actuators and mechanisms for coupling the modules.
Snakes: Snake-like robots are advantageous for maneuvering in congested areas, and also have unusual potential for locomotion. For example, a high-degree-of-freedom manipulator resembling an elephant’s trunk can wind its way into pipes or around obstacles, carrying end-effectors, or camera or other sensors, into areas not accessible to conventional robots. As locomotors, snakes can travel through very small openings, yet their length allows them to negotiate substantial obstacles. We are developing compact joint/link modules for 3D snake robots in manipulation and locomotion applications.
Minifactory is a concept for a compact and easily reconfigurable assembly system for short-run production of high-precision devices (disk drives, cameras, etc.). Minifactory employs Sawyer motors (X-Y linear motors floating on an air film) to carry products around the factory and position them under precision assembly robots and other processing stations. A key component of the system is the 2-DOF (Z/Theta) overhead manipulator which needs high resolution and repeatability in X-Y (micrometer level); good speed (less than 1 second cycle times with 125 mm, 180 degree travel); and precise Z-force control for assembly. Preliminary testing of the first unit of the second-generation prototype indicates it will achieve the speed requirements and repeatability near the 1 micrometer goal.