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Lab 2: Feedback in Wall-Following and Velocity Control

Assigned: Monday, September 17, 2006.
Due: Monday, September 24, 2006.

This lab introduces feedback as an organizing concept for robot activity. Using an optical distance sensor, you will create a control system to drive the robot at a constant distance from the wall. Using quadrature encoders, you will create a control system to drive the robot to a commanded position.

Readings

  • Read section 3.6, 3.7, 3.8, 6.1, and 6.4 from Robotic Explorations. Don't worry about the assembly code, you don't have to use that.
  • Read chapter 1 from Behavior-Based Robotics.

Implementation Projects

Three robot bases will have already been provided in lab for carrying around the Blackfin Handy Board. Since we only have 3 BF-HBs at present, these will be all that are needed for starting the labs. You may extend the robots, but please share them.

Project 2.1: Wall Following

Mount an “ET distance sensor” onto your robot (a.k.a., the Sharp GP2D12) and implement wall-following as described in Robotic Explorations. Implement either the 2-threshold algorithm (too far / too close) or the 3-threshold algorithm (too far / just right / too close).

Note: wiring diagram will be provided—the sensor in the book is slightly different and is wired differently!

Experiment with sensor placement and discuss how this affects performance, particularly as the robot goes around corners.

Experiment also with threshold settings and discuss how this affects performance.

In your implementation, does the robot have internal state? Explain.

Write up your results as an InventionDB project and link to your iDB cube at the bottom of this page.

Project 2.2: Position Control

One quadrature encoder sensor will be provided to you. Mount these so that they turn as your robot drive wheel turns. LabVIEW VIs will provide an instantaneous measure of rotational velocity.

Using this feature, create a program that drives your robot for a fixed distance. Use the proportional-derivative approach described in the Robotic Explorations text. Also, you may experiment with the PID controller primitive included in LabVIEW. Your motor controller should include a way of specifying the distance setpoint. Your system should deal with overshoot—if your robot drives too far, it should reverse.

Write up your results as an InventionDB project and link to your iDB cube at the bottom of this page.


Student Links to InventionDB Writeups

Link to your InventionDB cubes here.

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Page last modified on December 13, 2007, at 03:38 PM