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[Bug] EV3 servo model fails at higher speed #953

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laurensvalk opened this issue Feb 18, 2023 · 2 comments
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[Bug] EV3 servo model fails at higher speed #953

laurensvalk opened this issue Feb 18, 2023 · 2 comments
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@laurensvalk
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bug Something isn't working platform: EV3 Issues related to LEGO MINDSTORMS EV3 software: pybricks-micropython Issues with Pybricks MicroPython firmware (or EV3 runtime) topic: control Issues involving control system algorithms topic: motors Issues involving motors

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@laurensvalk
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Describe the bug

Running open_loop.py with the EV3 large motor gives the output below.

It is a bit off at first (not yet tuned, as expected), but then goes wildly off course at higher speeds.

This looks more like an overflow somewhere.

image
@laurensvalk laurensvalk added bug Something isn't working platform: EV3 Issues related to LEGO MINDSTORMS EV3 topic: control Issues involving control system algorithms triage Issues that have not been triaged yet software: pybricks-micropython Issues with Pybricks MicroPython firmware (or EV3 runtime) topic: motors Issues involving motors and removed triage Issues that have not been triaged yet labels Feb 18, 2023
@laurensvalk laurensvalk self-assigned this Feb 18, 2023
@laurensvalk laurensvalk mentioned this issue Feb 18, 2023
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@laurensvalk
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This could well be the discrete time model (200 Hz) becoming unstable because the loop time is nearly 8ms instead of 5ms.

It did not appear so far with the patch in #955. We can re-open if this still happens with a loop time of 5ms.

@laurensvalk
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We can re-open if this still happens with a loop time of 5ms.

It looks that way:

image

@laurensvalk laurensvalk reopened this Feb 23, 2023
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@laurensvalk laurensvalk

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bug Something isn't working platform: EV3 Issues related to LEGO MINDSTORMS EV3 software: pybricks-micropython Issues with Pybricks MicroPython firmware (or EV3 runtime) topic: control Issues involving control system algorithms topic: motors Issues involving motors
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@laurensvalk