Parallel mechanisms may provide for structural rigidity and good dynamic
performance; however, their utility is generally limited by an inherently
small workspace. The use of actuator redundancy can simultaneously increase
the workspace and remove singularities. A novel method to perform multi-goal
optimization has been devised to determine the set of optimal and realizable
designs. Following this principle, a prototype of a 3 DOF spherical joint
module, the ``shoulder'' for a light-weight robotic arm has been built.
It is powered by four high-performance hydraulic actuators. The joint develops
200 Nm of torque around any direction with a supply pressure of 4 MPa and
has a moving mass of less than 1 Kg. The torque control bandwidth exceeds
50Hz. Patent pending.
High Performance Hydraulic Manipulator Shoulder Module
This joint has been redesigned for optimal structural properties by
Prof. L. Lessard and his co-workers (Department of Mechanical Engineering,
McGill University). An elbow joint with two actuators is also being designed
and constructed, taking advantage of advanced composite materials.