Data Acquisition

Mission

Abstracting hardware sensors into quality data that can be accessed over a software interface

Sensors

GPS

Hardware:

A Hockey Puck

For our first semester prototype, Alex selected the: Garmin GPS 18 5Hz ($200)

• Updates every 200ms
• Accurate to at least 3.5m, expected accuracy of ~1m
• 12 parallel satellite tracking, WAAS enabled
• Does not require a subscription to any service
• Voltage Requirement: 4.0-5.5V

Software: The GPS is attached to COM2 (RS232, /dev/ttyS1, 19200 8N1) on the TS-7800. The GPS outputs a rising edge signal to allow precise time keeping, gpsd interfaces with ntpd and reads the DCD line on COM2 to provide time information via network interface.

Gyro and Accelerometer

25¢

The gyro and accelerometer are a combo system created by SparkFun. It incorporates both the ADXL330 and IDG300 to enable measurements of acceleration along the x, y, and z axes and of angular rate about the x and y axes. For more information, please visit SparkFun's page on the IMU 5 Degrees of Freedom.

• IMU 5 Degrees of Freedom
• Voltage Requirement: 3.3V

Compass

Now in Green!

• PNI Vector 2Xe Compass Module
• SPI Interface
• Accuracy: Max: 2° RMS; Typical: 1° RMS
• Power Requirement: 2mA @ 3.3V

Wheel Encoders

We may be able to connect the encoder to the back of the motor instead of near the wheel. There is a recessed shaft (under a cover) at the back of the motor that is hexagonal (~0.79" diameter x ~0.17" long). As for mounting, there are four screw holes (size 8-32) equally spaced around the outside of the motor (~3.5" apart longways) and two recessed screw holes (size 8-32) inline with the outer holes (~2.7" apart longways). The inner holes don't have very much clearance to the motor wall near the outside (~0.15").

Laser Range Finder

Current LIDAR: Hokuyo URG-04LX

• Indoor model, not suitable to our needs

Next Semester LIDAR: SICK LMS

• Currently hoping to borrow one of these units from the Urban DARPA project
• Outdoor model, used by all serious competitors