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PAX CAN Protocol. Nithyananda Siva Jeganathan Gayatri Sagi Vamshikrishna Gudivada Raghuveer Koppala. Objective. To specify the PAXCAN protocol packets and data types for system wide use across the CAN network. Constraints. To use 11 bit IDs or 29 bit IDs
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PAX CAN Protocol • Nithyananda Siva Jeganathan • Gayatri Sagi • Vamshikrishna Gudivada • Raghuveer Koppala UK Aerial Robotics Team University of Kentucky
Objective To specify the PAXCAN protocol packets and data types for system wide use across the CAN network UK Aerial Robotics Team University of Kentucky
Constraints • To use 11 bit IDs or 29 bit IDs • 11bit IDs are sufficient as the number of IDs are far less and also simple to implement • Payload size to use 2,4, or 8 bytes • 4 bytes (unsigned long) uniformly across the network to incorporate all packet formats • Have a maximum of 64 tags only • After PAXCAN specification version 0.1, the number of different packets <64. So Standard CAN is sufficient UK Aerial Robotics Team University of Kentucky
Design: Sub-system data segments • Servo control packets • GPS Data • Autopilot Data • Miscellaneous • Heartbeats • Debug Packets UK Aerial Robotics Team University of Kentucky
Specification: Servo Control Packets • 4 Packets produced by Auto-pilot and consumed by Servo control. • A packet sent every 50 ms for • Rudder control • Elevator control • Throttle control • Aileron control • Pulse width variations in the range 0.5ms to 2.5ms is encoded inside the packet UK Aerial Robotics Team University of Kentucky
Specification : GPS Packets • 6 Packets produced by Auto-pilot and consumed by the camera sub-system • A packet sent every 250ms with • GPS Latitude • GPS Longitude • GPS Heading • GPS Altitude • GPS Speed and time • The encoding of the GPS latitude, longitude and heading information is in milliarc seconds UK Aerial Robotics Team University of Kentucky
Specification : Auto-pilot Packets • 4 packets sent every 50ms produced by the auto-pilot • Packets contain • Pitot speed • Pitot Altitude • Pitch Angle (consumed by Camera stabilizer system) • Roll Angle (consumed by Camera stabilizer system) • The pitch angle and Roll angle are encoded in milli-arc seconds UK Aerial Robotics Team University of Kentucky
Specification : Miscellaneous Packets • Contains some miscellaneous packets produced for some debugging and experimental setups • 2 packets below containing • Camera pitch information • Camera roll information are produced by Camera stabilization system for the photo-stitching system • The pitch and roll information is encoded in milli-arc seconds UK Aerial Robotics Team University of Kentucky
Specification: Debug & Heartbeats Packets • Debug packets are produced by the Radio/Debug system • Consumed by their respective destinations only • 2 packets one for receive and another for transmit • Heartbeats are sent to every sub-system every 1 second by the Radio/debug module • For sanity checking of the system UK Aerial Robotics Team University of Kentucky
Thank You! UK Aerial Robotics Team University of Kentucky