The Task:
build a <6″x6″x6″ robot to solve the line maze problem http://www.robothon.org/robothon/maze.php
The Plan:
Use the following bag of parts:
- Teensy++ micro controler
- 2 Pololu QTR-8RC sensor arrays
- L298N Dual Full-H bridge driver
- 2 Portescap gear head motors with encoders that where gifted to me (I’m afraid to look up how much they cost)
- Assorted mechanical components (wheels, chassis)
- Assorted discreet bits (resisters, capacitors and whatnot)
- Custom PCB laid out in Eagle
- Implement a Dijkstra route solver
- Implement a map building algorithm
- Implement PID / PWM motor speed control with odometery
- Some UI code
My goal is to have this bag of parts assembled into a robot that will track lines well enough to start implementing the mapping logic and performance tune the moter speeds and line sensors before moving to the route solving. I’m currently thinking the project will take about 3 months. 1 month to build the platform and get signes of life. 1 or 2 months to get the odometry and PID working well, and to implement the mapping and route solving.
If I get mechanical signs of life by the May PARTS meeting I’ll be pretty happy.
TODO list: (last update April 18, 2009)
- lay out schematic for PCB
- created library part for the teensy++ (done)
- PCB schematic and board layout review (mostly done)
- I have a needling feeling that I need to suffle a few signals around to free up the serial port pins.
- laid out schematic (done, see latest files here)
- map out and size data structures for mapping and route solving (only have 4K RAM but lots of flash and 2K EEPROM I can use.)
- Locate 2 cm weels or figure out how to rubberize the 1.746 cm mounting hubs into wheels (mostly done)
- mount motors and sensors to chassis. (done)
- bread board the encoder circuit to see if I can get away with using the IO pin pull ups (50Kohms) instead of the discrete 10K’s
- Fabricate the PCB
- Populate PCB and test.
- Mount PCB and connect sensors and motors
- Stub out program working top down mostly, then fill out the AVR specifics for PWM, timers, and banging the ports..