Programming Applied Sensors in FIRST Robots

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Programming Applied Sensors in FIRST Robots

• Chris Elston Team 1501

www.huntingtonrobotics.org Download sample
code www.frcsoft.com
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Basic Components

• Robot Controller Operator Interface
• Radio Modems
• Digital Sensors
• Analog Sensors
• Speed Controllers and Spikes
• Joysticks
• Motors Pneumatics

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Basic Components

• Reference material (where to find)
• 2004 Best year to look for documentation on
  controller, programming examples
• 2005 Best year to look for documentation on CMU
  camera.
• 2006 Not many new documents released

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Basic Components

• Digital Sensors
• Analog Sensors
• CMU Camera

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Digital Sensors
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Digital Sensors

• Joystick buttons
• Buttons
• Limit Switches
• Pressure Sensor
• Optical Sensor
• Reed Switches
• Thumb Wheel Switches
• Encoders

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Digital Sensors

• Example programming questions
• How does a limit switch work?
• How does a thumbwheel work?
• Optical sensors work?

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Digital Sensors

• The Limit Switch is a digital sensor. It can
  distinguish between two states whether the limit
  switch is pressed or not pressed. When the Limit
  Switch is not pressed, the robot interprets this
  value as a 1 (one). When the Limit Switch is
  pressed the robot interprets the value as a 0
  (zero).

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Digital Sensors
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Digital Sensors
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Digital Sensors
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Analog Sensors
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Analog Sensors

• Joystick Axis
• Potentiometers
• Rotational Rate Sensor (Yaw Rate Sensor)
• SMC Analog Pressure Sensor

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Analog Sensors

• Analog Inputs are defined as inputs that can have
  any voltage value between 0 and 5 volts, not just
  ON or OFF. Joysticks, Potentiometers, and Gyro
  sensors are typically connected to Analog Inputs.
  Both the Robot Controller and the Operator
  Interface (FRC system only) have the capability
  to measure analog inputs.

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Analog Sensors

• PWM Type Analog Inputs
• Operator Interface represented as a
• 0 to 254 0 to 5V linearly
• 10-Bit Analog Inputs
• Robot Controller represented as
• 0 to 1023 0 to 5V linearly

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Analog Sensors

• Always use 100kO potentiometers.

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Analog Sensors
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Analog Sensors
IS30 SMC Analog Pressure Sensor 0 to 120 PSI
full scale 0 to 5 Volts 0 to 1023 5 Volts 120
PSI 1023 unit 8.525 units per 1 PSI
resolution
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CMU Camera
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CMU Camera

• RS-232 Device with returned variables
• Vision Terms we need to understand
• Pixels
• FOV
• Blob
• Centriod

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CMU Camera
PIXELS
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CMU Camera
CMU Camera FOV (Field of View) What it can see
159 pixels by 238 pixels
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CMU Camera
CMU Camera BLOB
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CMU Camera
CMU Camera Centriod
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• Questions?
• If you have a thumb drive, come see me and I can
  copy all my reference PDF files and note for you.
  
• 350 MB required

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RAFFLE TIME!