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Saturday, 27 October 2007

This weeks roundup..

Another week of chipping away at stuff. My main attention has been with the CMUCam3 module. I've been able to flash various example firmwares to the CMUCam3 and it's all working lovely.

I now have two GNU Arm tool chains on the laptop. The Yagarto GNU ARM toolchain for MX21 (ARM9) work, and the CodeSourcery "G++ for ARM EABI" one for CMUCam3 (ARM7) work. As far as setup goes; the CodeSourcery toolchain takes priority (directory PATHs, etc.), with the Yagarto one being enabled via the custom makefile scripts used for MX21 work.

I've also place an order with Technobots (UK) They were a later supplier find, stocking quite a few parts I had ordered from the US, including the Pololu parts. My original Pololu order had four round robot chassis bases, but I forgot the spacer rods on that order. So I was able to grab two sets of spacers from Technobots. The intention currently is to put the four round bases together to form two platforms. Drill through the front top one to make a place to securely mount the turret assembly, and have the top back one somewhere to put the VC21 stack. Hopefully with enough space on the bottom deck to place the motor controller board and power supplies. Then it's back to determining whether the tiny motors and gearboxes can handle that much weight. My current gut-feeling is that they can't..

Technobots have also start supplying Dimension Engineering's Accelerometer boards. So I've order from them the +-2g Buffered 2 Axis Accelerometer module DE-ACCM2G. I've been using a similar MEMS device in the Nintendo Wii development in my day job, so I'm familiar with the intricacies of analysing the noisy output from a MEMS chip (to check out the internals of a Wiimote, head over to this SparkFun tutorial). The 5g Accelerometer module from Dimension Engineering uses the same Analog Devices chip used in the Wiimote. I'm hoping the smaller 2g device is just as sensitive, if not more so.
I can't wait to get this tiny module and hook it up to the ADC on the VC21RB1. The VC Robot COG has a LPC2136 (ARM7TDMI-S) core that contains two 8-channel 10-bit ADCs. Perfect for connecting the X-Y outputs of the DE-ACCM2G accelerometer. With this hooked up on the robot it will then be able to work out it's orientation vector with respect to gravity. I'm also think about using it in conjunction with the CMUCam3 analysis to determine if the motor controller has gone crazy and needs to be reset.

Another bit of software to add to this mix is RoboRealm. I picked up a while back a very cheap USB web camera. So cheap it's default resolution is CIF (352x288), intentionally the same as the OmniVision CMOS camera sensor module used on the CMUCam3. I should be able to prototype an image processing pipeline for the CMUCam3 using RoboRealm, before moving this across to CMUCam3 firmware. Initial results from experiments in RoboRealm look encouraging, but I know it's going to be a huge effort to move any image processing pipeline routines from RoboRealm across to the very limited CMUCam3.

Finally here's a cute photo of the CMUCam3 in it's turret assembly -

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