Max acceleration limiting

Are there any features that you would like to add to the VESC?
Posts: 1
Joined: 26 Sep 2018, 15:47
Location: United States

Max acceleration limiting

Postby jmding » 26 Sep 2018, 15:55

It is useful to have lots of current capability to be able to climb hills, but due to the limited travel of many control interfaces (trigger remotes, thumb wheels), it is often difficult to precisely modulate throttle. As a result, vehicles can often be "twitchy," or otherwise behave too extremely. Commuters, riders in areas with pedestrians, or less aggressive riders may prefer the more "mellow" ride experience of a lower torque system, but still need high current capability to climb hills. Signal averaging helps solve this to some extent, but is not an ideal solution as very long integration periods would be needed, reducing responsiveness.

Instead, if the gear ratio and wheel diameter are known, it is trivial to estimate the vehicle's acceleration from motor position. A PID control loop can be implemented to reduce current when acceleration breaches a preset, configurable value. This allows the user to reduce the sensation of a twitchy throttle or extreme ride, while still having full access to the maximum torque available by the drive train for climbing hills.

Posts: 309
Joined: 28 Mar 2016, 14:37
Location: FR Valence

Re: Max acceleration limiting

Postby pf26 » 28 Sep 2018, 08:31

What kind of vehicle are you talking about ? Usually, there is quite a lot of inertia to limit the acceleration rates..
Most likely you could modulate your current reference according to the measured acceleration using a custom app (ie, not changing the main firmware). Or just modify the existing app that yields your current reference from (ADC, ppm UART.. ?)..

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