@@ -171,15 +171,19 @@ Using the grid search approach again, we first tried with 40 (robot falling forw
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@@ -171,15 +171,19 @@ Using the grid search approach again, we first tried with 40 (robot falling forw
We changed the setpoint to 585 and tried values of p between 40 and 70. As before, 70 caused violent oscillations and instability. Both 55 and 40 seemed more stable. We decided to continue testing with a value of 40.
We changed the setpoint to 585 and tried values of p between 40 and 70. As before, 70 caused violent oscillations and instability. Both 55 and 40 seemed more stable. We decided to continue testing with a value of 40.
Additional observation: The robot seems to stop briefly once in a while. This seemed to happen more with p = 70 than with p = 40.
Additional observation: The robot seems to stop briefly once in a while. This seemed to happen more with p = 70 than with p = 40.
*I value:*
We observed that once the robot started falling in any direction (forwards or backwards) it would generally keep slowly falling in that direction until tipping over (despite also driving in that direction in an attempt to balance). As such, we needed a stronger reaction on past accumulated errors, which is exactly what the integral variable controls, so we experimented with different I-values.
We observed that once the robot started falling in any direction (forwards or backwards) it would generally keep slowly falling in that direction until tipping over (despite also driving in that direction in an attempt to balance). As such, we needed a stronger reaction on past accumulated errors, which is exactly what the integral variable controls, so we experimented with different I-values.
Initially the I-value was 4, and as just explained we needed a stronger reaction on past errors, so we attempted increasing it.
Initially the I-value was 4, and as just explained we needed a stronger reaction on past errors, so we attempted increasing it.
We tried to change the i-value - which was 4 initialy
| Integral Value | Status | Observation |
- 5: better
| --- | --- | --- |
- 6: better
| 4 | Poor | Keeps slowly falling |
- 7: - maybe better
| 5 | Slightly better | Keeps slowly falling |
- 8: poorer
| 6 | Better | Usually manages to correct aggressively enough |
| 7 | Possibly better | Looks similar to 6, hard to tell if improvement|
| 8 | Worse | Reacts too violently often ends up falling to the opposite side |
We decided to finish up the experiments (long) before having tried all possible combinations of parameters values, as it seemed pointless to go on when seeing no significant improvements to the robot's behaviour - continuing would not improve on our understanding of the effects of the different PID parameters further. However, the parameter search inspired by grid search did provide us with a more structured insight into the effects of the different parameters than had we just tried varying each parameter on a whim.
We decided to finish up the experiments (long) before having tried all possible combinations of parameters values, as it seemed pointless to go on when seeing no significant improvements to the robot's behaviour - continuing would not improve on our understanding of the effects of the different PID parameters further. However, the parameter search inspired by grid search did provide us with a more structured insight into the effects of the different parameters than had we just tried varying each parameter on a whim.
