Autonomous Robot Line Painter

Original Design

Our design consisted of a 4-wheeled robot, which had two drive wheels in the back and two caster wheels in the front. This robust design was chosen to fit our needs of being able to drive over grass as well as have a very limited turning radius. The robot also had to know its position on the field at any given time, which would require some type of localization. We settled on the idea of using optical encoders on each of our drive wheels for information on position, and then laser triangulation to provide closed-loop feedback. A spinning mirror would be mounted on top of the robot, which had an infrared laser pointing at it from the base to provide our triangulation localization. A paint can would be mounted to the back of the robot and actuated by a servo motor.

Original CAD Renderings

Concept and Layout

After coming up with a design for the robots frame, we had to plan how we were going to control the drive circuitry as well as the laser triangulation hardware and algorithms. After careful consideration of necessary hardware that would be on our robot and our overall system concept, we determined that our layout had to be fairly complex and would require multiple voltage levels. We also had to ensure that out design would be able to run for long periods of time (which required optimizing our power consumption) as well as being sure our entire design was safe.

We came up with the power concept outlined below, which pulled off of 2 12-volt lead acid batteries and was split into 24V, 12V, 5V, and 3.3V. To follow our safety requirements, we also had multiple switches and one emergency stop button, which are also pictured.

Power Diagram

After power needs were determined, we designed our overall system layout. It revolved around using 2 dsPICs, one to control the drive train, and the other to control the laser hardware, triangulation algorithms, and also actuated our painting mechanism. Since one dsPIC was in charge of driving, and the other was in charge of determining the position, we communicated between the two of them using wireless serial communication via 2 XBees. More in depth coverage of how all of our hardware worked together can be found in the Hardware section.

Control and Laser Circuitry Diagram