Robot%20Sensors

1
Robot Sensors

• Kevin Watson
• and
• Rich Petras

2
Overview

• Sensors
• Micro Switch
• Gyro
• Encoders
• Command Sequencing
• PID Control

3
MicroSwitch

• Digital input
• Be sure to set as an input in User_Initialization(
  )

4
Encoders

• Kinds
• Mechanical
• Optical
• Types of output
• Resolution

5
Gyros

• Types
• Mechanical
• Ring Laser
• MEMS
• Using
• Bias
• Drift
• Integration

6
Command Sequencing

• Why do we want to do this?
• How does it work?
• Robot example....

7
What is PID Control ?

• PID control can be used any time you have a
  variable that you want to control and a way of
  measuring that variable.

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P I D

• P - Proportional - The amount of control is based
  on (proportional to) the error between where we
  want to be and where we are.
• I - Integral - The amount of control is based on
  the total error over time - the summation or
  integral
• D - Differential - The amount of control is based
  on how fast the error is changing - the
  difference.

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What are Gains ?

• The gains tell you how important each of the PID
  terms are.
• Kp - Proportional Gain - Determines how fast your
  system reacts to error
• Ki - Integral Gain - Determines how hard your
  system will push to overcome error.
• Kd - Differential Gain - Limits the change in
  response to error. Helps to dampen or smooth the
  reactions.

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How do I Tune my System ?

• Start by setting the gains low. You can set Ki
  and Kd to zero to start.
• Increase Kp until the system starts to react
  quickly enough. It will overshoot if you set it
  too high.
• Now increase Kd to compensate for overshoot. Now
  the system should react smoothly.

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How do I Tune my System ?

• But you might notice that it never reaches the
  goal. That is because resistance in the system
  is holding it back and as you near the goal, the
  proportional term gets smaller.
• Now it is time to increase Ki. Over time the
  error will build and the I term allows the system
  to overcome resistance.
• Now go back and adjust each of the terms to get
  the response you want.