obo-Magellan Robot Project

Robo-Magellan Robot Project - "Odyssey"

After many months of effort, here is Odyssey, our SRS/Servo Robo-Magellan contest entry. What is Robo-Magellan you ask? It is a contest devised by the Seattle Robotics Society, inspired by the problems to be solved for the DARPA Grand Challenge. It is an outdoor, autonomous, robotic navigation contest. A Robo-Magellan robot must be able to autonomously drive around a 500ft. square area of the Seattle Center, avoiding trees, rocks, park benches, garbage cans, light posts, railings, sculptures, and many other obstacles, and find orange road cones placed at specific waypoints. The GPS coordinates of the cones are given out 30 minutes in advance of the contest, and the robot that navigates autonomously from the start to the finish cone in the shortest amount of time, wins the contest. The only remote control that is allowed is for a safety shut-off switch should the robot run into trouble. Each robot gets three tries to navigate to the final cone. The best time of three is used for their final score.

The Design:

Our robot is a monster. The contest rules state that the robot cannot weigh more than 50 pounds, Odyssey weighs in at 48 pounds even. Bob and I have worked hard and long on this robot, and inside, it contains a culmination of all our electronics efforts to-date. Of course, this robot would never have come together, if it weren't for our sponsor, NPC Robotics (plug-plug). They provided the excellent motors, and a motor controller that can easily move this beast over almost any terrain with ease, without any shortage of power or torque.

Bob shot the initial snapshot above during the final assembly phase of the robot. Notice once again, Bob's excellent CAD design, and how close the final product closely resembles the drawing. I think the only major changes that were made was the tail-wheel assembly, and the location of the GPS dome. Since weight was such an issue, Bob literally weighed every nut and bolt on the robot, and had the CAD program calculate the final weight, so we knew if we built the design, we would be under the 50 pound weight limit.

Here is a laundry list of technologies we have on-board:

	Almost every single board in our BotStack robot bus, main, sensor, CPU, navigation, camera, radio, and motor control.
	Environmental Grade Sonar Array
	GPS System with WAAS correction
	6-degree of freedom inertial guidance system (The grey box on top of the robot)
	2-axis Magneto-Inductive Compass
	20fps Camera & Computer Vision System
	R/C Receiver for Remote Safety Fail-Safe.
	12v Permanent Magnet Motors with optical-encoder feedback for closed loop control and odometery.
	100amp Motor Controller

Here is another photo of it from the front, and the inside:

Navigation:

Navigating the Robo-Magellan course could be accomplished in a number of different ways. We chose to use GPS, combined with a 2-axis compass, and a home-brew inertial navigation system. We chose a WAAS enabled, OEM model of GPS unit made by Garmin. The GPS-18 LVC. Since it is an OEM unit it needs a mechanism for reading and storing waypoints, off of the robot. We built this nifty handheld unit to walk the course and store the waypoints, and then download them from the handheld device into the Robot just before the competition.

Here is our home-made inertial navigation unit. It has three ceramic gyro's, and two accelerometers to yield 6-degrees of freedom of inertial measurement. The compass board mounts just below the gyro board, with the same footprint, and all of this is housed in the square box on the top of the robot. All of these measurement instruments, combined with the GPS should give us fairly accurate position and heading computations as the robot moves through the course, with or without a consistent GPS signal.