Well the first quadrotor has finally arrived. Thanks to the folks at http://www.quadrocopter.com/, I have a Mikrokoper QuadroKopter XL. I've decided to swap out the stock Mikrokopter flight controller in favour of another. Thanks again Don Anderson at Gumstix for sponsoring this project. I'm outfitting the vehicle with a Overo FireStorm and Robovero expansion board. Using the Robovero's onboard 120Mhz NXP LPC1769 processor, 3 axis accelerometer, magnetometer and gyro should provide a good low level controller for stabilization and attitude estimation. In the future I'll be outfitting the vehicle with a GPS antenna and receiver. This information will be fed into a kalman filter to update the position estimate. The Robovero has ample input/outputs. A requirement for my research will be tether tension measurement. I have received a Futek LCM300 load cell. Using the Robovero's ADC, I should be able to get a good estimate of tether tension. I plan to design and build a miniature gimble system to mount the load cell which will give me the direction of the tether. I have designed a custom PCB to provide the necessary I2C logic level conversion, connector interface for the Mikrokopter motor speed controller and LED drivers (they came with the kit, might as well make it look cool). I shipped the design off to Advanced Circuits, pretty good deal for students, $33 for a single board. Turn around time should hopefully be less than a week. It was just an initial design, I'm sure there will be more revisions. It was a good learning experience with Eagle and designing custom PCBs.
One of the primary reasons for using an Overo was the ease of implementing code on it. Using Quanser's Quarc software along with MATLAB Simulink, I can quickly test sensor and actuator communication. Thus far I have sucessfully established communication with the motors (with 11 bit resolution), accelerometer, gyro and magnetometer. Most of the code currently resides on the Overo but eventually it'll be moved to the LPC microcontroller. I'm slowly generating/modifying the stock firmware by adding my custom functions (IMU reads, motor controls ...). It was actually a lot more straightforward than I was expecting. Hopefully things will continue to progress. I'm hoping to have it flying indoors in the next week or so. More updates to come soon.
Last modified Sun, 10 Feb, 2013 at 22:59
