Arduino Controlled Rex 14 Mobile Robot
Last updated (8/31/2011)
This project is based on the Rex 14 Mobile Robot base
. The Rex 14 Mobile Robot base has (2) 12 Vdc drive motors, each with a 500 PPR quad. encoders.
The first construction step is to solder the power leads to the drive motors. The motors can be easily removed to make this easier. Second, several holes are drilled in the base to allow the motor and encoder leads to pass through the deck to the control electronics which will be mounted above.
Max/Rex decks are made of ABS. ABS is very easy to work with and especially easy to drill. Unlike some other materials, ABS will not crack or shatter while being drilled. (Tip: To drill larger holes, first drill a smaller pilot hole. While ABS will not crack, it is very tough and can catch a larger drill bit and stall your drill)
At this point, wire way holes were drilled into a REX 14 round additional deck. The deck is mounted with the 5" mounting brackets. The Arduino controller will be mounted on the upper deck so the motor leads will pass through both decks. The Ardumoto
DC motor driver snaps onto the top of the Arduino Duemilanove
once the headers and terminal blocks are soldered into place.
The Power Distribution board will supply 12vdc to the Vin pin on the Ardumoto. This will be used to power both the Arduino controller and the motors. A power switch is wired to the switch connection to the Power Distribution board and a fuse (2A fast acting) is inserted. Both are required before power will pass from the battery to the outputs of the Power Distribution board. The power distribution board will also supply 5vdc if required. Now the Power Distribution board and the Arduino are mounted using double sided tape. Double sided tape will hold the boards in place while the robot is tested. If we like the location of the boards, they can be more permanently mounted with stand offs and screws in the future.
The 12vdc rechargeable battery will be mounted using hook and loop fasteners (Velcro?) (Tip: Attach the fuzzy side of the fasteners to the battery first. Then mount the battery to the robot, this will insure that the battery will match up with the base. Let the battery sit a few minutes while the adhesive sets) Hook and Loop Fasteners can be purchased from RadioShack (Part # 64-2345).
Now the battery is securely mounted and can be easily removed for charging or transport of the robot.
The robot is ready for basic motor testing.
Now that the motor driver is up and running, we can't have the robot running around bumping into things. Three MaxBotix LV-MaxSonar-EZ1
sonar units were installed with Zagros Robotics sensor mounting brackets.
Now that the robot is ready to roam around the USB cable limited the roaming range of the robot to nly a few feet while connected to a computer. To elevate this problem an Xbee module was installed. The Sparkfun Xbee package
comes with an Arduino Xbee module and a USB Xbee module. Once the connectors are soldered on to the Arduino Xbee module and the USB driver is installed on the PC everything was quickly up and talking.
The 5 inch deck brackets where replaced by 10 inch backets to allow more access to the battery and power distribution board. Another deck was also added to provide a top to the robot.
More to come...