Development of an interchangeable end effector mechanism for the Ranger telerobotic vehicle

The Ranger program at the Space Systems Laboratory (SSL) at the University of Maryland is a demonstration of an extremely low cost, space flight experiment. The Ranger vehicle is designed to perform teleoperated spacecraft maintenance. Completing the various tasks included in spacecraft maintenance requires several specific tools. This paper describes the Ranger interchangeable end effector mechanism (IEEM). Its design allows Ranger to change end effectors to utilize the appropriate tool for the various tasks. The Ranger vehicle is designed with four manipulators. A seven degree-of-freedom (DOF) grappling manipulator securely attaches the vehicle to the work site. A 6 DOF camera positioning manipulator allows the operator to position a stereo pair of video cameras for visual feedback. The two remaining manipulators are the 7 DOF dexterous arms. They are the primary means by which Ranger accomplishes its required tasks. At the end of each of these dexterous manipulators is an IEEM. This paper begins with a brief overview of the Space Systems Laboratory and the Ranger program. The constraints leading to the requirements for an IEEM are described. The following section then describes the design strategies and the down selection process resulting in two candidate designs, taper and pneumatic connector type. Next, the leading candidate design is described in detail, followed by a preliminary discussion of failure modes and planned testing. The paper concludes with a brief review and a section discussing future work.