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input | diameter right (mm) | diameter left (mm) | error right (mm) | error left (mm) |
|---|---|---|---|---|
100 | 1340 | 1370 | 14.02 | -0.98 |
90 | 1340 | 1370 | 94.18 | 79.18 |
80 | 1520 | 1600 | 103.90 | 63.90 |
50 | 2440 | 2730 | 177.73 | 32.73 |
Average radius error: 70.57
CAR 3
input | diameter right (mm) | diameter left (mm) | error right (mm) | error left (mm) |
|---|---|---|---|---|
100 | 1670 | 1560 | -150.98 | -95.98 |
90 | 1670 | 1560 | -70.82 | -15.82 |
80 | 1830 | 1720 | -51.10 | 3.90 |
50 | 2730 | 3030 | 32.73 | -117.27 |
Average radius error: -58.17
Notes
- It should be noted that the reported error refers to curvature radius not diameter. This means that when car 2 completes a semicircle, on average the model mispredicts its position by 7.057cm * 2 = 14.114cm. According to the partial data gathered, the misprediction can be up to 36cm. Still, it is not required for the model to be 100% correct. Indeed the main idea behind the steer controller is to associate a reference steer input given by the identified model with a PID or a PI that corrects its error over time. Considering that it takes about 4 seconds for the car with steer input 50 and motor input 150 to complete the semicircle, the PID will have 4 seconds to correct an error of 36cm.
- The trajectory followed by the car with constant steer is not a perfect circle but more similar to an ellipse with very low eccentricity.
- The curvature radius does not seem to change with the motor input.
- The curvature radius of car 1 saturates for input above 100. Signals 110 and 120 gives exactly the same curvature radius. For cars 2 and 3 this happens even before at input 90.
EFFECT OF PWM AND STEER INPUT ON THE SPEED DYNAMICS
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