Skye Sweeney's Build Log

I purchased the Pololu IMU and integrated it into the robot over the last few days. I was able to get the magnetometer and the accelerometers to work quickly with the supplied code. But I had issues with the gyro. After re-reading everything, I discovered that the  gyro code provided is not a standalone gyro not the gyro on the IMU. They are the same part, but the I2C address is different. Quickly changing the address had that part up and running as well. Continue reading →

Last week I got called out of town and did not have a chance to work with the parts that have started to come in. Today I caught up on my sleep (I had 16 hours in the last 3 days), fixed a few computer problems that had come up, and then adjourned to my secret lair. First thing I did was to mechanically attach both the Pololu IMU and servo mux. I then connected up the servo mux such that either the RC transmitter has full control over the chassis, or the processor does. The switch is based on the third channel of my RC transmitter. Works like a charm. Continue reading →

Started to order parts. First thing will have to be a new RC TX/RX with a third channel to control a Pololu servo mux. With this I will be able to have the processor or the receiver have control of the motor and steering. I also need to order the mux, servo cables, a GPS, an IMU, a new processor board, a power regulator module, XBee telemetry modules, and a bunch of other items. I just keep telling myself I am stimulating the economy.

The SparkFun AVC competition requires that the robot avoid obstacles placed in its way. These take the form of red 55 gallon drums. So if it was not hard enough to navigate around the building, trying to avoid the barrels is just that much harder. Now I think I have solutions for the waypoint navigation, but I am missing a good solution for the obstacles.

This weekend I went to a flea market with my wife. At one of the stalls a ran across an old plastic gun that connected to a computer game for “duck shoot” type games. Its a big orange revolver made by American Laser Games. So I took a chance an picked it up for a dollar.

At home I find it is mostly a lens and a phototransistor. An opamp, some discreets, a trigger switch, and a custom chip make up the rest. At the end of the cable is a gameport and a parallel port connector.

So now my obstacle avoidance system concept includes a modulated laser pointer pointing forward and a lens and phototransistor to pick up the dot. with a narrow enough field of view, this might just work.

Today it stopped raining enough I was able to get the RC car outdoor to run. I was able to clock the car at 18 MPH. Fast enough to win at last year’s AVC, but not likely for 2012 and most certainly not for 2013. I will have to upgrade the car from NiCad batteries to something with more power. I may also need to upgrade the stop Traxxis motor.

But for now, the car goes plenty fast for collecting data and trying out various navigation concepts.

I have had my eye on Craig’s List for severl months looking for a 1/10 scale RC car to use as the chassis for my 2013 AVC robot. Just recently a Traxxis Rustler came up for a reasonable price. Although it was a difficult process, I managed to pick it up this evening. The batteries are charging, and if the rain stops tomorrow, I will go out and test it.

The car is stock with a NiCad battery and a normal brushed motor. The catalog entry claims it can go 35 MPH. I wonder if I can control it that fast!

First milestones will be to just put a sensor platform on the car and collect data. Need to get a GPS, 9 DOF data, and TX signals logged to an SD card for post analysis.

The next milestone will be a simple controller to drive the robot in a simple pattern at slow speed. Life is good.