Throttle interface for sensitive high power setups

[zombiess]

Folks ride high horsepower motorcycles on the freeway at 1/8th throttle all the time, and in town at even lower throttle settings. You learn to control your wrist precisely.

yes, but a motorcycles throttle controls torque, not speed! This is a very big difference.

 

[ZOMGVTEK]

If its CHEAP, it sounds fantastic.

I've been somewhat interested in testing out such a device, but perfecting it sure can be time consuming...

 

[John in CR]

If its CHEAP, it sounds fantastic.

I've been somewhat interested in testing out such a device, but perfecting it sure can be time consuming...

Coming up with a better throttle than those typically sold for ebikes should be a simple matter. They just have no idea what is needed because on a 250W ebike even a momentary switch would work pretty well as a throttle. I actually have a throttle that works fine, and a bunch of others that have a short range of motion including a Magura. I have a broken "good" one somewhere. I'll try to dig it up, as well as sacrifice one of the others and see if I can come up with a better, reliable and cheap solution. My son's got one of those short twist jobs on his ebike running a lot less power than my bike, and I absolutely hate riding that bike primarily because of the care and focus required with the throttle. It forces me to ride around with a death grip on the bike.

 

[ZOMGVTEK]

Coming up with a better throttle than those typically sold for ebikes should be a simple matter. They just have no idea what is needed because on a 250W ebike even a momentary switch would work pretty well as a throttle. I actually have a throttle that works fine, and a bunch of others that have a short range of motion including a Magura. I have a broken "good" one somewhere. I'll try to dig it up, as well as sacrifice one of the others and see if I can come up with a better, reliable and cheap solution. My son's got one of those short twist jobs on his ebike running a lot less power than my bike, and I absolutely hate riding that bike primarily because of the care and focus required with the throttle. It forces me to ride around with a death grip on the bike.

I'm with you there. It's amazing how much you need to care about the throttle once you hit a few KW. A co-worker has a 350W bike that might as well have a switch for a throttle. You can barely tell if it has any 'speeds', you just slam it WOT and the bike creeps along.

I'm fairly happy with my setup as it sits. The 1/2 grip I have on it now is AMAZING compared to the junk full grip I got with the GM kit. A death grip sure is required with that thing at 6KW. And then you're worried about the thing breaking and going uncontrollably into WOT, which happened to me more than once.

If I made such a throttle device, I would get terribly involved and demand perfection. I'll just let someone else make it and see how it goes. If its terrible, then I might be forced to get involved.

 

[amberwolf]

What about the stuff they use on MCs like the Zero?
http://www.zeromotorcycles.com/shop/index.php?main_page=product_info&cPath=5&products_id=85
Is that any better, rotation-wise?

 

[Alan B]

Folks ride high horsepower motorcycles on the freeway at 1/8th throttle all the time, and in town at even lower throttle settings. You learn to control your wrist precisely.

yes, but a motorcycles throttle controls torque, not speed! This is a very big difference.

Actually it controls fuel flow which is not really torque but closer to power.

And ebike throttles control PWM not exactly speed.

Making a torque (or power) throttle is one thing. That's not quite what is proposed here. Of course with a micro you can do almost anything.

The Magura is already quite good if you span it out to use the whole range. It is already better than most hall type throttles.

I don't think the throttles on my motorcycles had more than 90 degrees rotation. That is a lot for your wrist.

If you want to mimic a motorcycle throttle then make power proportional to throttle position, and start with a good linear throttle like the Magura, and span it out fully.

 

[John in CR]

Until we have torque throttles, we're stuck with what we got, and that reality is a throttle that works differently at different speeds, so the guys doing micros need to get a wire tied in to detect speed. eg at very low speed somewhere in the range of 20-30% throttle from there on up is the same as 100%, but as speed increases that relationship changes to where at high speed anything below say 80% throttle is the same as 0% throttle.

Sure the most critical is the low speed stuff, where it's downright dangerous, so if the MC spreads out the effect of the first 1/4-1/3 of the physical twist to be 50% or so of the electrical range the throttle will be better than what we have, but the increased sensitivity at cruise is going to be bothersome. Something that varies with speed will probably seem weird at first, but someone will have to try it to see if it's comfortable once you're accustomed to it.

Alan, you're right that the range of motion on mine is actually too much for the wrist, and on my first hubbie bike I really didn't like it, because having only 2kw on tap meant a lot of WOT, which required a change in grip in the process. On my current bikes at much higher power, the long pull is almost totally a non-issue, because I so rarely use WOT. When I get on the highway and really use all of the upper half of throttle position, or when I'm cruising at 35-40mph on the lower roads and execute a pass my change in grip has become instinctive.

We really need a torque throttle incredibly bad, and the CA option must not really work at very high power, since Arlo1 hasn't been singing and dancing its praises. In the meantime my double range throttle will have to do, so I wish I could find more.

John

 

[stingray17]

Until we have torque throttles, we're stuck with what we got, and that reality is a throttle that works differently at different speeds, so the guys doing micros need to get a wire tied in to detect speed. eg at very low speed somewhere in the range of 20-30% throttle from there on up is the same as 100%, but as speed increases that relationship changes to where at high speed anything below say 80% throttle is the same as 0% throttle.

Sure the most critical is the low speed stuff, where it's downright dangerous, so if the MC spreads out the effect of the first 1/4-1/3 of the physical twist to be 50% or so of the electrical range the throttle will be better than what we have, but the increased sensitivity at cruise is going to be bothersome. Something that varies with speed will probably seem weird at first, but someone will have to try it to see if it's comfortable once you're accustomed to it.

Yeah, you might have hit the nail on the head, John! I really like that idea of using the speed of the bike to change the throttle range & sensitivity. It could create a much safer and more fun setup for medium to high powered ebikes and it seems to me that as long as it's smooth it would be easy to get used to. Can just connect a pin on the MC to the speedo or DD hall sensor output to measure the speed directly, or it could be read from CA's serial output (with ~1sec delay, but you also get battery info).

So maybe at 0-5mph, the throttle control ramps up very slowly, 3/4 turn is only 15-20% "throttle". And when the bike is moving close to maximum speed, the throttle ramps up extremely quickly and then gets sensitive over the 80-100% range. In the middle, you have a more flat full range throttle. The software would have to adjust the curve based on speed data, dampening the adjustments so the effective throttle doesn't shift too fast. The only thing I'm wondering is how hard will it be to maintain a constant speed that is not WOT... (add one button cruise control function = fixed?)

Edit: Long term, maybe a better torque throttle is what's needed? I dunno. It seems to me that we're always going to have problems implementing a torque throttle based on measuring input amps and varying the speed selector "throttle" input to the controller. What is needed is a BLDC controller that does this internally and offers a torque throttle input... right?

 

[dennyt]

What is needed is a BLDC controller that does this internally and offers a torque throttle input... right?

Yes, this is what we need!

 

[John in CR]

I just went out for errands before the rain comes and for the first time really paid attention to what I do with the throttle. Now I understand why I abhor the death grip short twisters. I hold the throttle very lightly and really move my hand around a lot. It's all instinctive and natural, but on take off I twist using the U formed by my thumb and base of my index finger, but then I release that a bit as I accelerate, rolling the throttle a bit extra with only the friction of my fingers. The target speed seems to determine where I re-grip with a loose hold including my thumb. The result is a little wrist movement with fingers palm and thumb that give me full throttle range with total comfort and control with no twitchiness. I use throttle activated regen too, so control at all times is quite important, and what I have seems totally natural. My bike is a pedal forward low and long upright, so I don't have weight on my hands like with many bikes, so I don't know how it would work with them, but the long twist definitely works for me. I'm sure that when I commuted by motorcycle for nearly a decade that I used the throttle in a similar manner, because just twisting using the wrist and holding those different positions would be quite uncomfortable, and you guys probably do to, but the extreme sensitivity at low speed is biting you.

 

[zombiess]

Folks ride high horsepower motorcycles on the freeway at 1/8th throttle all the time, and in town at even lower throttle settings. You learn to control your wrist precisely.

yes, but a motorcycles throttle controls torque, not speed! This is a very big difference.

Actually it controls fuel flow which is not really torque but closer to power.

And ebike throttles control PWM not exactly speed.

Making a torque (or power) throttle is one thing. That's not quite what is proposed here. Of course with a micro you can do almost anything.

The Magura is already quite good if you span it out to use the whole range. It is already better than most hall type throttles.

I don't think the throttles on my motorcycles had more than 90 degrees rotation. That is a lot for your wrist.

If you want to mimic a motorcycle throttle then make power proportional to throttle position, and start with a good linear throttle like the Magura, and span it out fully.

The throttle doesn't control fuel flow on a motorcycle unless it's diesel, it controls the airflow, throttle body/bodies. Kinda besides the point of the thread just wanted it corrected.

PWM is used to control the speed of the wheel, correct? The PWM is modulated by the throttle so the throttle controls the wheel speed. The throttle has no control direct over the current.

I've also ridden liter bikes with 90 degree throttles and they are much much more controllable than high powered ebike setups with small wheels. But I still prefer a standard range throttle on a motorcycle because I don't race. I have to look into what it would take to put an inductive current sensor on the phase wires and try to regulate the controller that way, but I'm not sure if I want to spend the time doing it. This would probably be the best solution.

That Zero throttle looks identical to a $50 Magura.

Low cost and simple are the keys here.

I think some pots to adjust input voltage range, output range and number of steps coupled with a single switch to select range up/down could be a winner.

Does anyone know if the infineon controller throttle input is low or high imp? I'm thinking I should probably buffer the voltage out through an op amp.

 

[Alan B]

True on a bike the throttle controls the air, then the carb adjusts the fuel to maintain the mix. Still throttle controls power the engine can make at that RPM.

Ebike Throttle controls PWM which sets the motor voltage. The speed of the motor is a function of the voltage and the load. So doesn't control speed directly. But the motor is trying to make a speed proportional to the voltage. The throttle control of PWM is over-ridden by lots of things such as max battery current, etc., so for example at low speeds the top part of the throttle does nothing as the max current won't allow the PWM to go full on. If it did the controller would blow right out (which happens when folks mod their controllers too far).

Best simple arrangement is to read battery current and feed back on that. Like the CA does, but do it better. Makes the throttle a power control. CA can do this okay, but needs more tuning, perhaps differential term, perhaps different control algorithm to work better at the higher power levels.

Reading the speed and incorporating that into the algorithm might be helpful. Some time ago I was thinking that an interesting throttle algorithm would be a percentage control that looked at several parameters and controlled whichever was highest. Control on speed and battery current. So if you set the throttle at 20% it would initially control on 20% battery current max, then as speed built up it would control on 20% speed. That makes it easier to maintain a speed than a strict current control which will tend to ramp up and up, requiring modulation of the throttle to maintain the speed. Might want to tune the relationship of current and speed to find the right balance.

 

[zombiess]

Thanks for some of the clarification Alan. I knew load would affect the motor speed for a given PWM, but I didn't know that battery current had the ability to over ride the commanded PWM.

Your idea for power/speed control sounds interesting. I haven't played around with current control on the CA yet, but I thought I read it's only implemented as PI control and missing the derivative function which is causing some issues. I only know a little about PID and need to do more reading on it myself to get a firm grasp.

 

[Alan B]

I think that you are right, and I have not tried it out yet either, but have seen others who were pretty happy with it.

In controls we often avoid the differential term, PI is easier to tune and "good enough" for many things. I suspect that Justin stopped at PI because it was enough for the motors he was using, but those were probably under 2KW. Going higher might require more sophistication. Things like different attack/decay gains may help, and adding a damping term is not hard to do. It is harder to tune all the knobs, though, and I can imagine that he didn't want to have to explain all that to the average user if it wasn't really needed.

One physical implementation that would really be nice is to put four plugs on the board. CA plugs in and out, and throttle in and out. Then it would be really easy to hook up, and remove if it failed. Just daisy chain it into the throttle and CA cables. 5V power comes off the throttle line, and the current sense is on the CA plug as well as the speed from the hall pulses.

Lots of possibilities.

 

[John in CR]

PWM controls both speed and current on our bikes. If battery current (measured) or phase current (calculated from battery current) reach the programmed limits, then the pulse width is narrowed. PWM is our only means of control, it's just that the fixed ratio of duty cycle commanded by our throttles is inadequate at low and high speeds, because so much of the physical range of motion is wasted. The speed switches sound like they work pretty well, but needs to be automatic, otherwise I'd surely forget to switch to low and end up on my back. Probably just some slightly different physical arrangement in the throttle itself to soften the linear result in the first 25% of rotation would be enough until a true current throttle control becomes available.

 

[zombiess]

I think that you are right, and I have not tried it out yet either, but have seen others who were pretty happy with it.

In controls we often avoid the differential term, PI is easier to tune and "good enough" for many things. I suspect that Justin stopped at PI because it was enough for the motors he was using, but those were probably under 2KW. Going higher might require more sophistication. Things like different attack/decay gains may help, and adding a damping term is not hard to do. It is harder to tune all the knobs, though, and I can imagine that he didn't want to have to explain all that to the average user if it wasn't really needed.

One physical implementation that would really be nice is to put four plugs on the board. CA plugs in and out, and throttle in and out. Then it would be really easy to hook up, and remove if it failed. Just daisy chain it into the throttle and CA cables. 5V power comes off the throttle line, and the current sense is on the CA plug as well as the speed from the hall pulses.

Lots of possibilities.

Alan, adding the connectors is a brilliant idea! I just need to decide how far I want to take this or if there is a better off the shelf way to do it. I've also been thinking about just making the throttle curve different (exponential for more control down low) and having 1 or several ranges like gwhy! has done.

PWM controls both speed and current on our bikes. If battery current (measured) or phase current (calculated from battery current) reach the programmed limits, then the pulse width is narrowed. PWM is our only means of control, it's just that the fixed ratio of duty cycle commanded by our throttles is inadequate at low and high speeds, because so much of the physical range of motion is wasted. The speed switches sound like they work pretty well, but needs to be automatic, otherwise I'd surely forget to switch to low and end up on my back. Probably just some slightly different physical arrangement in the throttle itself to soften the linear result in the first 25% of rotation would be enough until a true current throttle control becomes available.

John, I just wanted to say that what I bolded above in your statement has never happened to me at least 3 times :lol: Worst was a curb I came down off of from a median from a slow roll. Good thing I wait to make sure traffic is clear, don't wanna get squished by the soccer mom with a screaming brat in the back putting on lipstick while talking on her cell phone.

 

[John in CR]

The speed switches sound like they work pretty well, but needs to be automatic, otherwise I'd surely forget to switch to low and end up on my back. Probably just some slightly different physical arrangement in the throttle itself to soften the linear result in the first 25% of rotation would be enough until a true current throttle control becomes available.

John, I just wanted to say that what I bolded above in your statement has never happened to me at least 3 times :lol: Worst was a curb I came down off of from a median from a slow roll. Good thing I wait to make sure traffic is clear, don't wanna get squished by the soccer mom with a screaming brat in the back putting on lipstick while talking on her cell phone.

Thanks for reinforcing that I do not want to install any of my 3 speed switches, at least not on the handlebar, just somewhere hidden for noob first rides. My controllers are rigged for it. I can't decide whether or not it's fortunate or unfortunate that my procrastination pays off so often. I guess as long as I pick and choose the correct things to procrastinate about then I'm ok, especially keeping death at the very top of that list. 8)

John

 

[zombiess]

Bringing this one back from the dead. Finally had some time to make some progress. I'm hoping to test it this week but no promises. Actually I want to test it tomorrow . I just need to hot glue down the trim pots, add on the correct plugs and I should be good to go.

I designed this one specifically around the Xie Chang line of controllers which are quite popular with the ebike crowd. I ride a high powered bike and the throttle is very sensitive to movement. What I've done is tried to solve some of that by building this micro controller circuit which allows me to convert the throttler interface from linear to an exponential curve so there is more resolution in the low range and less in the high range. It also allows you to adjust your voltage start point and end point so you are able to get the full range of motion out of your throttle. I also added an adjustable filter/delay that is variable from 0 to about 2 seconds. This should help to smooth out throttle transitions especially on rough terrain. If you have a setup with some power you are probably quite familiar with how hard it is to hold a throttle position over bumps. If you ride a really high powered setup then you've probably ended up in unintentional unicycle mode more times than you would like.

Circuit draws 11ma from the 5V throttle plug.

[youtube]yDoTS9cftI0[/youtube]

 

[Tench]

This looks like a great solution to the sensitve throttles we suffer with, looking forward to your resluts.

Simon.

 

[gensem]

Interesting.... subscribed.

 

[Paul_G]

Bringing this one back from the dead. Finally had some time to make some progress. I'm hoping to test it this week but no promises. Actually I want to test it tomorrow . I just need to hot glue down the trim pots, add on the correct plugs and I should be good to go.

I designed this one specifically around the Xie Chang line of controllers which are quite popular with the ebike crowd. I ride a high powered bike and the throttle is very sensitive to movement. What I've done is tried to solve some of that by building this micro controller circuit which allows me to convert the throttler interface from linear to an exponential curve so there is more resolution in the low range and less in the high range. It also allows you to adjust your voltage start point and end point so you are able to get the full range of motion out of your throttle. I also added an adjustable filter/delay that is variable from 0 to about 2 seconds. This should help to smooth out throttle transitions especially on rough terrain. If you have a setup with some power you are probably quite familiar with how hard it is to hold a throttle position over bumps. If you ride a really high powered setup then you've probably ended up in unintentional unicycle mode more times than you would like.

Circuit draws 11ma from the 5V throttle plug.

[youtube]yDoTS9cftI0[/youtube]

Please make a bunch of them to sell

My Bomber is a beast off the line...heck sell them to Stealth as they do not have a fix.

 

[zombiess]

Please make a bunch of them to sell

My Bomber is a beast off the line...heck sell them to Stealth as they do not have a fix.

As long as it works, the plan is to sell a bunch of them. I just need to do some testing to verify they are bug free, send out a couple prototypes for others to test (I'll ask for volunteers when I'm ready) and then go into production. Goal is to keep them cheap and sell a a lot of them. I'm thinking of offering a kit form as well for those who want to DIY and save me the trouble of assembly, but it's pretty easy.

I don't want to get ahead of myself though, first up is testing this bread board prototype after securing it with hot glue and duct tape (maybe some zipties too so I can get the kludge trifecta), then a perf board version once I know it works, then prototype PCBs to send out, then final PCB production and sales. Now that I'm at this stage I'm anticipating things going much faster because I'm quite motivated.

I've got tons of ideas if you read this thread, but I decided to go with the simplest solution for now to keep it easy for the end user and I figured 3 adjustment pots would be the simplest. It also makes writing instructions on setting it up much easier. Technically it can be done with nothing more than a screw driver once you have it connected between your throttle and controller, but a DMM will make it easier to do the initial setup.

I didn't have this ready for the Grange bike race which forced me to turn down the power a lot so my rider could control the bike, this would have let him run in a much higher power configuration and made his life easier.

 

[Paul_G]

Please make a bunch of them to sell

My Bomber is a beast off the line...heck sell them to Stealth as they do not have a fix.

As long as it works, the plan is to sell a bunch of them. I just need to do some testing to verify they are bug free, send out a couple prototypes for others to test (I'll ask for volunteers when I'm ready) and then go into production. Goal is to keep them cheap and sell a a lot of them. I'm thinking of offering a kit form as well for those who want to DIY and save me the trouble of assembly, but it's pretty easy.

I don't want to get ahead of myself though, first up is testing this bread board prototype after securing it with hot glue and duct tape (maybe some zipties too so I can get the kludge trifecta), then a perf board version once I know it works, then prototype PCBs to send out, then final PCB production and sales. Now that I'm at this stage I'm anticipating things going much faster because I'm quite motivated.

I've got tons of ideas if you read this thread, but I decided to go with the simplest solution for now to keep it easy for the end user and I figured 3 adjustment pots would be the simplest. It also makes writing instructions on setting it up much easier. Technically it can be done with nothing more than a screw driver once you have it connected between your throttle and controller, but a DMM will make it easier to do the initial setup.

I didn't have this ready for the Grange bike race which forced me to turn down the power a lot so my rider could control the bike, this would have let him run in a much higher power configuration and made his life easier.

I volunteer for a stock Bomber test and John at Stealth would love to test it as well I bet

Plug and play with connectors for the throttle would be great...heck I'll pay for one as I'm not asking for free.

 

[zombiess]

Plug and play is always nice and something I might try, but it requires sourcing connectors. I change out all my controllers throttle and halls connectors to different ones made by molex I get from Fry's. I just don't care too much for those cheap plastic connectors most of the controllers come with. These are one step up, but not as nice as the ones ebikes.ca uses. Works out well because I almost always cut my throttle wire shorter anyways to keep the installs cleaner, I dislike having wires all over the place when I can avoid it.

What kind of throttle connector does Stealth use? A picture would be nice. If you want to test one on a Stealth for me I'll send one your way after I'm sure it works OK on my own bike. I need to make sure everything works as expected such as my 3 speed selector switch, check for strange faults / etc.

I gave the pots a lot of adjustment range so some testing should be done when setting them up, with the bike off the ground. It is possible to set the begin and end ranges out of the normal range which can cause some funky results, but I'm leaving it like this because it allows for a really large range of adjust ability which should enable wider compatibility with controllers.

 

[Paul_G]

Plug and play is always nice, but requires sourcing connectors. I change out all my controllers throttle and halls connectors to different ones made by molex I get from Fry's. I just don't care too much for those cheap plastic connectors most of the controllers come with. These are one step up, but not as nice as the ones ebikes.ca uses. Works out well because I almost always cut my throttle wire shorter anyways to keep the installs cleaner, I dislike having wires all over the place when I can avoid it.

True but you need to think of all the other 99% that have the original connectors...source the connectors IMO.