The MAVRIC Mechanical Team is responsible for the design, testing, and manufacturing of all mechanical and electromechanical systems on our mars rover analog. This includes major subsystems like the rover’s chassis, suspension, and robotic arm, as well as other considerations like camera mounting and control.
All designs our developed in-house first in Solidworks (see figure 0), before undergoing several gate reviews and revisions in-CAD before manufacturing plans and other necessary files for production developed. The rover (see figure 1) was largely manufactured in facilities provided by Iowa State University. Waterjets, laser cutting machines, manual and 4-axis CNC mills were all employed to name a few machines. The manufacturing and welding of the chassis was generously donated by Quality Manufacturing out of Urbandale, Iowa.
The rover employs the use of a Rocker-Bogie suspension which has its articulation partially limited for more optimal performance in high-speed-rough-terrain conditions (see figure 2). The rover’s six wheels are individually driven by 16,000 no-load RPM and 214 m-Nm stall torque motors, attached to planetary gearboxes.
The chassis was designed to have numerous mounting holes for subsystem modularity, to allow for greater amount of iterative improvement and to minimize operational downtime. For instance, if the rover suspension were entirely reworked it the current suspension could be removed and a new one attached within an hour without having to modify anything on the rover. This allows us to experiment with new subsystems without compromising rover functionality and permits backwards compatibility, so should new systems fail or prove unreliable they can be replaced with older ones.
The electrical box, camera mast, and robotic arm were all designed to interface with the chassis in such a way that they’re easily replaced and entirely modular. The camera mast (figure 3), shows how 3D printing can be used to great effect to provide complex yet robust mounting options.
The rover’s robotic arm utilizes a worm drive to power its primary shoulder joint, a linear actuator for more precise forearm movement, an internal gear drive for base rotation, and a dual-motor wrist control that offers both pitch and yaw to the operator. This, in conjunction with the proposed controller mapping configuration outlined in figure 4, gives us an intuitively controllable 5-DOF robotic arm.
M.A.V.R.I.C.’s Mechanical Team has the following objectives for Spring 2018 and Fall 2019.
- Further develop and test the robotic arm through modification of the arm itself and the development of more intuitive controllers and or control schemes.
- Develop a proposal for a new suspension that reduces overall rover weight and provides better turning capability and overall performance versus the rocker-bogie currently employed.
- Design and manufacture camera and sensor mounts as needed for the systems team and determined by the strategy team.
- Work with the science team to ensure their system is mechanically sound, robust, and ready in time for the URC competition.