The Mars Exploration Rover (MER'03) flight mission represents state-of-the-art technology for target approach and instrument placement on Mars. MER baseline operations require multiple communication cycles, frequently over a period of several sols (Martian days), to enable a rover to approach and place an instrument on a target rock up to 10 meters distant. For future Martian surface operations, it is desirable to conduct the entire 10-m target approach and instrument placement with one cycle in a single sol. This improved capability will significantly increase the science return achievable within the life of the mission. JPL Robotics is working on two major technologies to enable single-sol approach-and-placement operations:
1. Visual tracking for approach with hazard avoidance
A rover pose estimator alone, including a visual odometer, does not provide sufficient accuracy for single-sol instrument placement. The visual target-tracking technology has been shown to provide sufficient accuracy but requires careful validation studies in terms of tracking reliability (success rate) and accuracy. Tracking should perform well even during winding rover motions for hazard avoidance. Several technology elements are available or under development:
- Image-feature matching and predictive tracking
- Controller handoff between different stereo views of the environmental - from telescopic pancams, to medium- field-of-view navcams, to wide-angle, low-mounted hazcams
- Rover-mast calibration and accurate camera pointing
2. Rover-based manipulation to place an instrument with collision avoidance
After the rover reaches a target through visual tracking, the rover needs to be placed at a good location where the arm can be deployed to place an instrument. The rover needs to avoid hazards, and the arm needs to avoid collisions with the environment. Examples of technology elements available or under development for this capability include the following:
- Rover-base placement within the arm's reach of the target
- Accurate arm placement through visual monitoring
- Arm-motion planning and collision prevention during motion execution, with rover structure and with the environment
Some of these technologies are being infused into the MER flight software for real experiments on Mars during MER's extended mission. Others are planned for future mission infusion, increasing science operation capabilities, and enabling sample return.
