Difference between revisions of "Data Acquisition"

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(Wheel Encoders)
(Wheel Encoders)
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===Wheel Encoders===
 
===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).  It isn't long enough (< 0.25" I think) so the encoder can fit directly around it, but there may be a way to connect a rod inside of it -- there is a 0.385" hole in the shaft (that has something in it now) and a set screw (pin, really) on the side that is holding it in.  I haven't been able to take this apart yet.  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").
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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).  It isn't long enough (< 0.25" I think) so the encoder can fit directly around it, but there may be a way to connect a rod inside of it -- there is a 0.385" hole in the shaft (that has something in it now) and a set screw (pin, really) holding it in which goes all the way through the shaft.  I haven't been able to take this apart yet.  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").
 
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Revision as of 11:16, 28 September 2007

Mission

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

Sensors

GPS

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



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.


Compass

Now in Green!


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). It isn't long enough (< 0.25" I think) so the encoder can fit directly around it, but there may be a way to connect a rod inside of it -- there is a 0.385" hole in the shaft (that has something in it now) and a set screw (pin, really) holding it in which goes all the way through the shaft. I haven't been able to take this apart yet. 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