Programming Workshop Making Sense of Sensors

Erik A. Cokeley - 2008

Programming WorkshopMaking Sense of Sensors

FIRST 2008


Presenter– Erik A. Cokeley– Involved in FIRST for 11 years

• Mentor - Hightstown High School - Team 1089

– NJIT - Junior– Computer Science Major– Experienced with the Microchip PIC– Autonomous robots– Program in C, C++, Assembly, Java– Familiar with the FIRST Default Code– Co-Founder CB Thinkx LLC


Workshop Outline– Review the Default Design– Sensor Selection– Collecting Sensor Data– Interpreting Data– React!– Some examples– Questions


Design Flow• Competition Mode• Autonomous Mode

• 26.2 ms


Sensor Selection• Identify the problem• What information do we need• How do we gather that information

– More than one sensor might be needed• How to select sensor

– Make sure it reads what you want…– Compatible with your machine– Accuracy & Repeatability


Collecting Sensor Data• Read the documentation.

– No two sensors work exactly the same– Test your sensor– Only use the sensor if it still helps

• Poll or Interrupt Models• Sampling Rate & Precision• Processing Time/Storage Requirements


Interpreting Data• Aggregation

– Multiple Sensors– Over Time– Running Total– Running Average

• Correlation– Give the data meaning and purpose

• Data Issues– Noise Margin– Estimation/Linearization– Dead Zones

• Programming Issues– Overflow– Hysteresis


React!• State Machine• Where to React

– Reaction time• Priority

– Sensor Priority • Man vs. Machine

– Machine Functionality• Saving resources (battery)

• Control the Robot


An Example• Time for some code!


Questions?


For More Info

• Erik Cokeley – [email protected]

• www.cbthinkx.com/first/frc

Programming Workshop Making Sense of Sensors

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