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Summer 2011
NASA Independent Verification and Validation Facility (IV&V)
As a college intern at NASA's IV&V Facility I worked with engineers and two high school interns to develop three SWARM robotics testing platforms. As the Facility's name implies, IV&V focuses primarily on verification and validation of flight software for NASA spacecraft. As NASA plans increasingly complex robotic missions, new verification and validation (V&V) techniques will need to be developed in order to ensure mission success in the future. Traditional V&V techniques are not designed to handle certain robotic behaviors such as SWARM-type cooperation between multiple robots. These platforms were designed to be low-fidelity analogues that would allow IV&V engineers to begin investigating new testing procedures.
Above is a map generated by one of the robots. The red squares represent the actual locations of obstacles, the blue diamonds are the outlines of the obstacles based on sensor returns, and the green rectangle is the robot in its starting location.
Project Details
SWARM robots are meant to be deployed in large numbers and therefor must have a relatively low cost per unit. Because it is difficult to complete tasks such as Simultaneous Localization and Mapping (SLAM) at a low price-point, our group modified the robots' environment to reduce the difficulty while still allowing us to develop a SWARM platform. Namely, we restricted the robots to a roughly 8' x 8' grid. The grid lines allowed the robots to navigate using line sensors in lieu of more expensive wheel encoders, gyroscopes, and/or IMUs.
Technical Details
- A total of three SWARM platforms were built.
- The drive base consists of two independently driven tank treads.
- The on-board processor is an AX-11 microcontroller.
- Three infrared-sensitive light sensors (with integral infrared sources) are used to detect the grid lines.
- A SHARP IR range finder is used to detect the obstacles.
- Due to the lack of an available servo, a potentiometer is coupled directly to the pan motor for the IR range finder. This allows the single range finder to scan approximately 180 degrees and function as a "poor man's LIDAR."
- Two contact switches are used to maintain the zero/offset of the scanning motor.
- A Synapse RF Engine radio transceiver allows each SWARM platform to communicate and share data with a base station (laptop). The base station can then disseminate the shared map information to all three of the platforms, allowing each robot to more effectively navigate its environment.
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