Development Robotic Arm System Testbed for the Mars Sample Return Campaign

The NASA-ESA led Mars Sample Return campaign will be the first to deliver samples from another planet to thousands of scientists worldwide who will rewrite textbooks with their discoveries. A critical step in the campaign is the transfer of sample tubes from the surface of Mars to the ascent vehicle which will require a highly dexterous robotic arm and advanced control strategies. Development and testing of the control algorithms is being carried out at NASA’s Jet Propulsion Laboratory on R&D testbeds while the flight robotic arm is under development by the ESA. The algorithm testing requires a seven degree of freedom robotic arm testbed closely resembling the kinematic configuration of the flight design which utilizes comparable mechanical components and avionics. The actuators of the testbed were designed around off the shelf drivetrain and sensor components which resemble the operation and performance of their flight counterparts, without the added complexity and expense of extreme radiation, vibration and thermal robustness. The cable harnessing is largely off the shelf and is integrated into a cable management system commonly used on industrial robots which is cheaper, easier to install and modify than a custom ribbon cable solution. Each actuator was tested on the benchtop for performance characterization and qualification of load capability. The integrated robotic arm was kinematically calibrated using vision-based metrology and applied load test cases. This paper describes the design, construction, and commissioning of this testbed, dubbed Bradbury, which meets the needs of the sample handling algorithm testing campaign while remaining relatively inexpensive and efficient to construct and reconfigure.