Problem with low throttle speed limits

[toni-1]

When i set 6 kph throttle speed limit (Germany), the limit doesn' t work. The real limit is about 8 to 9 kph.

I think it is because (fwconfig.h): // Size of speed limit ramp down interval. // If max speed is 50 and this is set to 3 then the // target current will start ramping down when passing 47 // and be at 50% of assist target current when reaching 50.

define SPEED_LIMIT_RAMP_DOWN_INTERVAL_KPH 3​

So, if you set 6 kph the ramping down starts when passing 3 kph. 50% at 6 kph. 0% at 9 kph.

[danielnilsson9]

Yes that's how it works, maybe a bit too simple to give a perfect result but worked good enough for higher speeds. I did however test it at low speeds to (6km/h) and it worked reasonable well when current limit is set low.

What do you have your throttle current limit set to for those levels?

[toni-1]

I set current limit to 60% and speed limit to 4% (4 kph). So i get about 6.6 kph.

Global speed limit for standard levels has problems. See #195

[danielnilsson9]

Ok yes that is quite a lot of power for such a low speed limit, especially if on BBSHD, that will cause overshoot and also oscillations. I would recommend 20%% or lower.

[toni-1]

20% doesn't work well. The problem is the 3 kph ramp down with slow speed limits. With 4 kph limit and 60% current limit i get: 1 kph with 60% current 2 kph with 50% 3 kph with 40% 4 kph with 30% 5 kph with 20% 6 kph with 10% 7 kph with 0%

[EigenMania]

Why not just ramp the current down to 0% at the speed limit? Then also the speed limit would be a bit more reflective of the top speed of the bike.