Summer Research - Henry

PID Control for VEX toss up

- PID stands for Proportional Integral Derivative
- It’s a software solution for controlling a system
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- Set point is the target value. i.e. the goal
- Process variable is start point
- Sensor reads the process variable
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- The difference between the set point and the process variable is called the error
- The new process variable is found by multiplying the constant (pGain) by the error
- The process of determining the value of pGain is called Tuning
- The error is calculated by subtracting the process variable from the set point
- This is done in a while loop so it will keep calculating until the error is negligible, meaning the set point has been reached.
- pGain can determine the amount of time it takes for the set point to be reached, or if the set point will be reached at all (this is called Offset)
- Offset occurs because of “disturbances” which are anything that alters the system’s output.
- An integral is the area under the curve of a function
- Error is constantly recalculated
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- Pseudo Code for both proportional and integral control with sample values. Gains have to be found experimentally
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- Use of both proportional and integral control improves results in both time and accuracy.
- Derivative is the rate of change of the error with respect to time
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- PID makes it everything even better.
- Noise is quick, random changes in the input signal that creates rapid fluctuations in the error
- Can be caused by vibration or electrical interference.
- Depending on the problem, you may need to use a different combinations, maybe just P, PI, PD, etc.