Control Narrative

Design Criteria

The Autonomous Control System of the vessel must meet the following design criteria:

• Capable of keeping the boat on a fixed (straight) course between waypoints using only GPS navigation and rudder control (changes in speed should not occur during general navigation)
• Capable of accomplishing a 90⁰ course change with a turn radius not more than 3 meters
• Capable of successfully navigating to within 2 meters of a pre-defined waypoint
• Capable of navigating a course successfully while experiencing 30 cm waves

Control Modes

Autonomous

Autonomous mode is defined as the boat being able to be released in a body of water and autonomously navigate without the use of pre-defined paths. It requires a control system that is able to locate and follow the shoreline (at a reduced speed) based on a specified minimum depth. The boat would first trace the shoreline of a pond and then begin a grid pattern to fill in the outlined shore.

Path Following

Standby

Path Upload

Return Home

The Return Home control mode is defined as the boat being in an autonomous state where the only waypoint in the queue is the 'Home' location (the position from which the boat was launched on that mission).

Remote

The Remote control mode is defined as the boat being piloted from the shore manually over the wireless link. In this scenario, the throttle and steering get updated each time a new wireless message is parsed. The base station (a computer) will use inputs from a human machine interface to encode the throttle and steering information for transmission over the wireless link.

The following are errors to which the system must respond:

• Loss of Wireless Link (Type 1): If, while in Control Mode: Remote, no communication is received for three (3) seconds, log an error indicating "Loss of Comms, Type 1" and appropriate metadata. Automatically switch to Control Mode: Autonomous, clear the waypoint queue and set next waypoint to position (lat, long) of last good communications and hold.
• Loss of Wireless Link (Type 2): If, following return to position of last good communications, wireless link is not reestablished after 10 seconds, log an error indicating "Loss of Comms, Type 2" with appropriate metadata. At this point, automatically switch to Control Mode: Return Home.
• Low Battery: If the battery voltage drops below the permissible level (with a delay of 10 seconds), log an error indicating 'Battery Low' and appropriate metadata. Automatically switch to Control Mode: Return Home. Boat will return to launch point autonomously.