Gimbal Robotic Joints: Kinetostatic Analysis

The demand for more accurate and efficient robotic systems in technology highlights the importance of the drive systems for robot manipulators. Gimbal mechanism is a nonlinear novel design for replacing traditional robotic transmission systems such as gearboxes and revolute joints. This nonlinear direct transmission (DT) is one of the most recent types of transmission methods in robotic applications. It is an alternative approach for traditional drive methodologies such as gearboxes and direct drive transmission (DD). DT provides dynamic coupling and joint interactionattenuation. Its ability to be set for a desired working point and its smooth input-output characteristic in addition to its varying reduction ratio leads to a desired force and motion behavior for a manipulator. In this paper, the use of Gimbal transmission as a robotic joint is considered and the kinetostatics of the new robot is investigated. The input-output characteristic and their relationship with reduction ratio are analyzed. Then theeffect of gimbal mechanism as a replacement for simple revolute joints in a robot manipulator -Stanford Arm- is investigated. Based on Manipulability Ellipsoid analysis the amount of force at the tip of the simple manipulator is compared with the same quantity for a manipulator inwhich one of its revolute joints is replaced by Gimbal mechanism. It is shown that this replacement leads to much greater forces at the tip of the manipulator in that desired direction. Greater forces are also achievable in any direction by adjusting two other design parameters of Gimbal mechanism.

Keywords:

Gimbal Drive , Non-linear DirectTransmission , Direct-drive , Manipulability Ellipsoid , Kinetostatic Analysis