Active and passive control of a revolute-prismatic flexible composite-material robot arm

Abstract

The focus of this paper is on reducing the positional inaccuracies of a flexible, revolute-prismatic robotic manipulator due to the undesired static and dynamic deflections. A strategy combining active and passive compensations is employed. Active control is performed by using a controller which compensates for both the rigid body and flexible motions. Passive compensation is by fabricating the robotic manipulator from advanced composite materials. This aids the controller in reducing the undesired static and dynamic deflections by increasing the arm's stiffness-to-weight ratio. The effects of large displacements, shear deformation and rotary inertia are included in the dynamic model of the robot arm. The displacement finite element along with Gear's method is adopted to approximate the solution. Comparisons are made of the performance of the robot arms constructed from conventional metallic materials and advanced composites. The positional accuracy of the end effector and the energy consumption of the actuators are enhanced by the simultaneous use of the nonlinear control and fabrication of the robot arm from advanced composites.