anyone used the 'current throttle' option for CA's?

[amberwolf]

If there is a time constant for this, you could lengthen it, but it will also change the way it reacts to current spikes, unless it is "smart" enough to see the faster rise time of the spikes (assuming they *are* faster rise time) and use a different, shorter, time constant.

 

[flexy]

I have been trying to get this working on my scooter, nothing is happening
My CA has always worked, but this is the first time I have used it for limiting the throttle, I tried using the basic speed and current limiting settings and these have no effect either.
My 18fet controller is connected to the CA as per Lyen's instructions with a diode to pull down the throttle signal.
I tested the voltage across the TH output and ground on the CA and it sits around 1.6-1.8V,This should be around 4V according to the CA instructions, Iterm max is set at 4V.
Any suggestions?

 

[Arlo1]

Did you set the ca to limit amps or speed?

 

[flexy]

I tried both, I also set the aux voltage input (8.17) to current limit.

 

[dennyt]

I just set up the Current Throttle on my bike today, and it seems to work... but with a lot of undamped oscillations. Cruising along at mid-speed, if I go from 0 throttle to 50% throttle, I get a 1/2 second delay, then a lot of torque, then a 1Hz overshoot cycle that last for about 4 cycles until it stabilizes. Looks like the 0.1 damping ratio curve here:

I noted the lack of a damping term in the PID settings, which Justin has addressed here. Has anyone else had a similar problem and found good settings to fix it? It's so bad I think I'll be switching back to the normal voltage or speed control throttle setup.

Also, the Crystalyte cruise control behaves very strangely now. It used to be that I would set my throttle to the desired speed, then hit the cruise button, and the bike would accelerate to that speed then stay there. Now when I do that, it slows down to a very low speed, and I have to use the + button to speed it up. If I hold the + button too long, the current goes higher than the current limit and stays there!! That's surprising. I guess the Crystalyte cruise control isn't compatible with the CA Current Throttle option.

My setup:
Magura 0-5k pot throttle with 2k pot on 5v input line
Crystalyte Analog Controller 35A
BMC V2-S front hub motor, 12S LiPo
Aux Threshhold set to 0.02

 

[Arlo1]

Are you limiting amps or speed? I got a email from justin to try iterm max so I will tomorow when I get the motor back together with the bigger phase wires and cooling fans.

 

[dennyt]

I'm limiting amps. I'll play with the Iterm settings, maybe adjusting them both higher will help.

Edit - increasing both did help.
ItermMax: I noticed the bike wasn't reaching top speed with the stock setting of 3.79v, so I bumped it up to 4.1.
ItermMin: Increasing this up to 2.0V helped. Above 3V, the throttle acted like a binary switch. At 2.0 there is still some oscillation, but about half as much as with the stock setting.

 

[Arlo1]

I'm limiting amps. I'll play with the Iterm settings, maybe adjusting them both higher will help.

Edit - increasing both did help.
ItermMax: I noticed the bike wasn't reaching top speed with the stock setting of 3.79v, so I bumped it up to 4.1.
ItermMin: Increasing this up to 2.0V helped. Above 3V, the throttle acted like a binary switch. At 2.0 there is still some oscillation, but about half as much as with the stock setting.

Yeh I found if you go to high with iterm min it will be to touchy as you start out!!!

 

[JvdW]

I am using the 'current throttle' option in amp limit mode with a PAS V5 on my front wheel as an input. The analog V5 is actuated with a spoke magnet and has a linear output with increasing speed (1.62V at 6.5 km/h up to about 3.2V at 40 km/h on a 28" wheel). This setup gives an 'automatic' power control where the power increases linear with the speed of the bike (the exact amount can be tuned with 'max amp', 'max throttle' and 'aux threshold' settings in the CA).

This 'automated amp limit' works very nice on level roads and at moderate speeds (up to 25 km/h). For higer speeds I have to adjust the settings to get a better match of the linear input with the much faster increasing air resistance. (I am working on a different input setup that generates a signal that looks more like the square of the speed.)

When riding in hills or in strong winds I bypass the CA and use the normal 3-speed selection of my EB206 controller.

Pro's of automated amp limit (personal opinion):
- smooth operation without switching or adjusting
- independent of pedaling speed and gear selction

Con's of automated amp limit:
- you waste battery-power when going downhill of have a good tailwind
- insufficient power when going uphill or in strong headwind
- the linear design of the pas V5 is a bad match to the actual power needed at different speeds (but it does a decent job up to 25 km/h which is a legal limit here in europe)

 

[Spacey]

Just did the mod last night on my HS3540 and sensorless 12Fet Lyen Mk1 controller.

Love it, so much more efficient as I suspect in gusty winds it will hold at a certain amount of power rather than trying to hold at a certain amount of speed and throwing all the power it can do stay at that speed. Cruising slower is much more controlled and the motor didn't get so hot.

The awful juddering I get from the Mk1 12 Fet sensorless controller can be ..err..controlled a lot better by just backing off the amps a little with the throttle. So far I am prefering this.

Was getting a dead spot after about 90% throttle where it would cut out unless I let go of the throttle and started again, a bit more resolution in the low speed setting would be nice, maybe a Log response rather than Lin on the throttle would be better.

Will try the Iterm Max and Min settings in a bit.

 

[dennyt]

OK, a couple issues with this mod:
1) The brake cutoff switch no longer kills power. I verified the switch is working, but the CA throttle input seems to bypass the cutoff. With the standard throttle setup, it worked.
2) The cruise control (crystalyte unit into crystalyte analog controller) no longer works correctly. Upon initial "set", the bike slows way down. On hitting the + button, the CA current limit is exceeded. Before the mod, "set" would keep the bike at the commanded speed, and the CA current limit would keep everything in check.

I'm actually enjoying the current throttle with my Magura throttle & Oury grips. Turning IntAGain down to 200 from 300 helps smooth it out too, though it's slow off the line. At 300 it would spin the wheel in the wet, which almost took me out on an off-camber start.

I also had an intermittent speedometer problem yesterday. On the ride home Tuesday it poured, but it was dry yesterday. The CA was displaying 0mph while I was moving, but occasionally the speed would jump up to 80mph, 120mph, 400mph, 600mph! When the 99mph limit was violated, the CA cut throttle I had to set the wheel diameter to 1mm to get home.

Upon troubleshooting tonight, 24 hours later, it worked perfectly right away. I opened up the CA and there was no moisture, no shorts, no broken connections, no smells. Hmm. Perhaps the wheel speed sensor had some water issue, or a partially broken wire?

 

[JvdW]

@dennyt
I had the same speedometer trouble with the CA too. After replacing the sensor (reed switch) with a unit from an old speedometer the problem was over. I suspect the CA reed switch 'bounces' to much.

Regarding the brake cutoff problem: I had similar issues with my controller+CA setup. In my case the controller doesn't start the motor after braking until the throttle is turned back to zero. I solved it with a 2-switch relay. The brake actuates the relay, the relay cuts off the throttle signal and activates the brake signal. Works perfect on my system. Other controllers may have different implementations of the brake cutoff function.

 

[gensem]

Can anyone post a link to the rc cycle analyst thread that has some settings discussed.
Im about to use a magura throttle with CA current throttle and im clueless about the settings.
Woulda I be able to remove the resistors from the magura?

 

[AussieJester]

^^^^all the settings for current control/ magura throttle are posted in the rc cycle.analyst thread, I posted my settings there, works a treat been using it ever since...

KiM

 

[gensem]

Aussie are you referring to this thread?

http://endless-sphere.com/forums/viewtopic.php?f=28&t=29846&hilit=beta+cycle+analyst&start=195

 

[AussieJester]

Aussie are you referring to this thread?

http://endless-sphere.com/forums/viewtopic.php?f=28&t=29846&hilit=beta+cycle+analyst&start=195

Yup. That's the one....

KiM

 

[llile]

I am having quite a lot of oscillation with a non-current throttle CA setup. Never oscillates when accelerating but anytime I am going at constant speed the motors just get pulses of energy. I am actually worried that it might fatigue some frame parts (I am riding a custom trike completely fabricated from scratch, and you worry about that sort of thing you know) I have goofed around with CA settings to no effect, but since I am not using a current throttle yet, it may have no effect anyway. All the CA can do now is pull down the throttle limit, not actually control anything.

I'm hoping the current throttle option will cure this. I'll post my results soon.

 

[amberwolf]

What happens if you directly connect the throttle to the controller?

I thought the CA was causing a similar issue with my new setup on CrazyBike2, but it is not--it is either in my throttle or in the controller itself. I can set a throttle position, and get smooth "power" up to the speed that position would give for those road/wind conditions, and then power falls off, speed drops, and power burps on, speed rises, then repeat cycle.

The effect is *slightly* different (more pronounced) when it runs thru the CA for some reason, but it is still there without the CA in the loop.

As it doesn't matter *what* throttle position or speed I "set" with it, it's not a speed-limiting function problem. But i have never seen this behavior in a controller before, so I don't know why it is happening. I assume it is a "feature" of the Grin Tech 12FET, but if so it's not one I like, and can't understand why anyone would, since you cannot cruise at any constant speed, you're always either accelerating or decelerating/coasting. It's uncomfortable, annoying, and distracting.

Also, everytime it happens, which is extremely frequently, my brain thinks something is wrong with the throttle position (like my thumb got lazy or somethign) so it makes my hand push throttle forward to increase the speed back to where it should be, and then I get a huge burst of power pushing me a couple of MPH faster than I want to (or am supposed to) go. Each ride I manage to eventually tame my hand from doing that, but then I find myself glancing down to see if wires have come loose or smoke is happening, because as far as my hindbrain knows, there's no reason for speed to not be approximately constant when the throttle is.... That glancing down means I'm not looking at what's in front of me and is eventually going to cause me a problem--I keep trying not to do it but it seems to be instinct at this point.

 

[mdd0127]

Sounds like the grin controller uses a current throttle even without the CA. When you lift the wheel off the ground, will the motor go full speed with only a little throttle input?

Constantly modulating the throttle is the one "drawback" of a current controlled throttle setup. It's more like the throttle on a gas engine. As conditions change, whether it's grade or drag, the torque required to keep a constant speed varies. A heavier bike with lower power will require a lot more modulation than a lightweight one with too much power. If you want it to cruise with no throttle modulation like a speed control throttle, you'll probably have to either adapt an aftermarket automotive cruise control or design your own. Since I'm used to ICE throttles, the current throttle was second nature to me. With the power that my bike was running, the speed throttle was just scary but the current controlled throttle was much more predictable, particularly in high speed offroad stuff. I think you'll find that your hand will instinctively be able to modulate it to maintain consistent speeds after you get used to it.

 

[veloman]

I tried playing with this again and I'm having a problem with it going full power whenever on.

I played with the settings and finally got it to stop (and the throttle doesn't work at all either) by setting AuxThreshold to 0.07

It seems the CA is sending a 3v or 3.93v signal automatically.

I do have AuxVoltage set to Amps limit which is what I want.

Any help on narrowing though all these variables?

 

[John in CR]

I tried playing with this again and I'm having a problem with it going full power whenever on.

I played with the settings and finally got it to stop (and the throttle doesn't work at all either) by setting AuxThreshold to 0.07

It seems the CA is sending a 3v or 3.93v signal automatically.

I do have AuxVoltage set to Amps limit which is what I want.

Any help on narrowing though all these variables?

Is that with the CA3 or an earlier V2 version? If earlier, then it sounds like the CA is connected wrong and the diode is missing. With those before CA3 the CA should never be able to send a voltage, only draw down the voltage from the throttle to the controller. The diode on the throttle override wire is what makes it one way, ie CA never sending a voltage to the controller.

 

[veloman]

its the early 2.1 version. I'll try putting a diode in, thanks.