Current multi-agent robotic testbeds are prohibitively expensive or highly specialized and as such their use is limited to a small number of research laboratories. Given the high price tag, what is needed to scale multi-agent testbeds down both in price and size to make them accessible to a larger community? One answer is the GRITSBot, an inexpensive differential drive microrobot designed specifically to lower the entrance barrier to multi-agent robotics. The robot allows for a straightforward transition from current ground-based systems to the GRITSBot testbed because it closely resembles expensive platforms in capabilities and architecture. Additionally, the GRITSBot's support system allows a single user to easily operate and maintain a large collective of robots. These features include automatic sensor calibration, autonomous recharging, wireless reprogramming of the robot, as well as collective control.
The nanosatellite optical downlink experiment (NODE) implements a free-space optical communications (lasercom) capability on a CubeSat platform that can support low earth orbit (LEO) to ground downlink rates > 10 Mbps. A primary goal of NODE is to leverage commercially available technologies to provide a scalable and cost-effective alternative to radio-frequency-based communications. The NODE transmitter uses a 200-mW 1550-nm master-oscillator power-amplifier design using power-efficient M-ary pulse position modulation. To facilitate pointing the 0.12-deg downlink beam, NODE augments spacecraft body pointing with a microelectromechanical fast steering mirror (FSM) and uses an 850-nm uplink beacon to an onboard CCD camera. The 30-cm aperture ground telescope uses an infrared camera and FSM for tracking to an avalanche photodiode detector-based receiver. Here, we describe our approach to transition prototype transmitter and receiver designs to a full end-to-end CubeSat-scale system. This includes link budget refinement, drive electronics miniaturization, packaging reduction, improvements to pointing and attitude estimation, implementation of modulation, coding, and interleaving, and ground station receiver design. We capture trades and technology development needs and outline plans for integrated system ground testing.
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