Ways to get Best possible throttle response.

speedmd

speedmd

10 MW
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Nov 14, 2012
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new england
Hi All

I am in search of a new controller/throttle for my modded gng setup but stuck as to which way to go to get what I am after. With the Mid drive and some 2+ kw going into it, it gets to be a hand full in the lower gears on difficult single track /trials speeds. Delay, dead spots, ramp speeds all add up to a much less than desirable throttle experience. Light weight and short wheelbase just amplify the issues. Tried the throttle tamer and it was a big improvement until my greentime fried it and the throttle for some unexplained reason, but still it was not solving all the issues that would make it a good feeling throttle.

The CAv3 sounds like a good way to go. Resistor or quality hall throttle? Do I need a torque sensor, or is it possible to get a great feel with just ramp and current/power limiting built into the CAv3 that would need to be sorted out. Hate to add another (torque) sensor if not needed. Any advise welcome.
 
A CA may do the job or if you fancy a bit of DIY http://endless-sphere.com/forums/viewtopic.php?f=2&t=61004 for about a $25 and a bit of time.
 
A PAS torque sensor is an option, not a requirement for the V3.

Presumably you will be looking at Current Throttle which will benefit from a nice linear throttle (eg Magura or hall with a linear magnet). The ramping and gain will certainly make the throttle more friendly, but to be honest, the V3 can introduce perceptible throttle delay. This is fine for making a powerful torquey bike controllable and street-friendly, but I'm not sure you will be pleased for your trials application.

I'm a huge fan of the product and don't want to discourage you from giving it a whirl, but your critical requirements for responsiveness are a cause for attention.
 
No Torque sensor..


I understand where you are coming from as regards controlling the throttle at trial speeds, you can imagine what problems I was having with 15kw on tap when geared for these speeds :mrgreen: its battery and pseudo phase current limiting controlled via throttle position. its work very well 'as is' but still in the process of tweaking and playing I am at the stage where I need to try it on some more technical sections as a throttle only control ( torque control ), hopefully this will be in the next couple of days.
 
Great both gwhy and teklektik on the same thread. Great things to follow for certain. :D

@teklektik, yes the delay would be a issue if not minimized for certain. Lots of other features are very nice on the CA that would also be needed, like a thermal rollback. Wondering how different the programing would be with the Arduino approach. Looks like some good options.

@gwhy, yes I want to have a super controllable launch with the throttle right off the line. Us Trials riders understand well what is needed. It is a bit of a challenge.
 
speedmd said:
Lots of other features are very nice on the CA that would also be needed, like a thermal rollback.
...
I want to have a super controllable launch with the throttle right off the line. Us Trials riders understand well what is needed. It is a bit of a challenge.
Click to expand...
Well - in the end, you really don't have to choose - you could do both. :idea:

You might spring for the V3 with eyes open and take it for a test drive. This is a nice easy off-the-shelf undertaking.
This may fulfill your needs, but if not, you could try this remedy as phase two:

  • Revert the V3 to V2 mode - that is, the throttle does not go to the CA but rather to the controller. This would lose Current Throttle as well as ramping and throttle gain features. However, you would retain the displays, presets, battery and performance statistics, as well as programmable LVC, current limiting, and thermal rollback.
    At this point you have restored your original throttle response and have some non-interfering V3 goodies.
  • As time allows, implement gwhy!'s controller and hook it to the controller throttle input as per normal. The V3 throttle overrides will still be in play.
This would give you many of the V3 features and an opportunity to utilize an alternate means of programmed throttle control.

There may be some argument between the two systems as the V3 tries to reduce throttle from gwhy!s box, but the CA will always win. If this proves to be rough or troublesome in some fashion, then a resistor or two would allow the CA override to be attached to the operator throttle before it goes to gwhy!s unit. This would result in a smooth rollback under any circumstance in the same manner as with the normal controller/V2/throttle interaction.

There may be an option to leave the V3 in PassThru mode and simply stack the V3 and gwhy! unit. This would preserve ramping features and should not incur throttle delays, but the segregated strategy above is simpler as a first cut and fully eliminates any question of delay.

Just a thought.... :D
 
The S12SH controller from BMSBattery can be switched over to current control. I don't know if that works on the throttle as well as the PAS though. They call it "torque simulation mode". If it works on the throttle, it would probably be a good solution to your problem, but I haven't tried it.
 
teklektik said:
You might spring for the V3 with eyes open and take it for a test drive. This is a nice easy off-the-shelf undertaking.
This may fulfill your needs, but if not, you could try this remedy as phase two:

  • Revert the V3 to V2 mode - that is, the throttle does not go to the CA but rather to the controller. This would lose Current Throttle as well as ramping and throttle gain features. However, you would retain the displays, presets, battery and performance statistics, as well as programmable LVC, current limiting, and thermal rollback.
    At this point you have restored your original throttle response and have some non-interfering V3 goodies.
  • As time allows, implement gwhy!'s controller and hook it to the controller throttle input as per normal. The V3 throttle overrides will still be in play.
This would give you many of the V3 features and an opportunity to utilize an alternate means of programmed throttle control.

There may be some argument between the two systems as the V3 tries to reduce throttle from gwhy!s box, but the CA will always win. If this proves to be rough or troublesome in some fashion, then a resistor or two would allow the CA override to be attached to the operator throttle before it goes to gwhy!s unit. This would result in a smooth rollback under any circumstance in the same manner as with the normal controller/V2/throttle interaction.

There may be an option to leave the V3 in PassThru mode and simply stack the V3 and gwhy! unit. This would preserve ramping features and should not incur throttle delays, but the segregated strategy above is simpler as a first cut and fully eliminates any question of delay.

Just a thought.... :D
Click to expand...

Great options. Sounds like a good way to go as it has a bunch of great features I am sure I will like. Look forward to see how gwhy makes out in the coming days with his current control.

Interesting d8veh on the current control controller option. Would love to hear from a user with a mid/high powered mid drive setup and get their impressions.
 
gwhy! said:
No Torque sensor..


I understand where you are coming from as regards controlling the throttle at trial speeds, you can imagine what problems I was having with 15kw on tap when geared for these speeds :mrgreen: its battery and pseudo phase current limiting controlled via throttle position. its work very well 'as is' but still in the process of tweaking and playing I am at the stage where I need to try it on some more technical sections as a throttle only control ( torque control ), hopefully this will be in the next couple of days.
Click to expand...

Hi gwhy

So your only controlling / limiting current with this. No change in ramp rate (how sudden it comes on). I am thinking throttle needs to be progressive as you dial it up. Great topic.

thanks for sharing
 
Only controlling the current and this is mixed with the speed so it gives good throttle control. The device ramps the speed up or down according to the amount of difference between requested current and actual current.
 
speedmd said:
Feedback loop. Understood. So if I understand the speed you mention, it would be the further you are from target current the faster it tries to close the gap from what is being delivered.
Click to expand...

yes. so with nice slow throttle progression the torque ( phase amps limit/current limit ) ramps up , but if you crack the throttle its similar to dumping a clutch, with just a speed based control the torque ( phase amp limit/current limit ) is at maximum from zero speed this is what makes everything so twitchy.
 
speedmd said:
Feedback loop. Understood.
Click to expand...
This closed-loop feedback technique is used universally by all these devices - notably the CA V3 and controllers with current or 'torque' throttle. There can be differences in the feedback algorithm but arguably most important is where the current is monitored. The CA uses battery amps instead of phase amps which gives very acceptable results for most builds - your requirements are likely more stringent - hence my cautious post above.

That said, the V3 also uses a fairly simple ramping algorithm that accounts for the largest part of the out-of-box default throttle delay. Failing to adjust this can give a misleading view of the base V3 feedback technique since disabling ramping makes the response much more brisk. These sorts of features can dampen responsiveness regardless of the device in which they are implemented and need to be considered with care in situations like yours.

speedmd said:
Interesting d8veh on the current control controller option. Would love to hear from a user with a mid/high powered mid drive setup and get their impressions.
Click to expand...
Merlin, a V3 user, is just now switching to a controller the built-in current throttle. You may wish to follow the V3 Beta thread posts about his configuration and experiences.
 
teklektik said:
speedmd said:
Feedback loop. Understood.
Click to expand...
This closed-loop feedback technique is used universally by all these devices - notably the CA V3 and controllers with current or 'torque' throttle. There can be differences in the feedback algorithm but arguably most important is where the current is monitored. The CA uses battery amps instead of phase amps which gives very acceptable results for most builds - your requirements are likely more stringent - hence my cautious post above.

That said, the V3 also uses a fairly simple ramping algorithm that accounts for the largest part of the out-of-box default throttle delay. Failing to adjust this can give a misleading view of the base V3 feedback technique since disabling ramping makes the response much more brisk. These sorts of features can dampen responsiveness regardless of the device in which they are implemented and need to be considered with care in situations like yours.

speedmd said:
Interesting d8veh on the current control controller option. Would love to hear from a user with a mid/high powered mid drive setup and get their impressions.
Click to expand...
Merlin, a V3 user, is just now switching to a controller the built-in current throttle. You may wish to follow the V3 Beta thread posts about his configuration and experiences.
Click to expand...

I think there will always have to be a compromise when using a throttle only control for speed and torque if you require a very fast throttle response that can deliver dialed in power in the blink of a eye..
 
gwhy! said:
I think there will always have to be a compromise when using a throttle only control for speed and torque if you require a very fast throttle response that can deliver dialed in power in the blink of a eye..
Click to expand...
At the end of the day, the throttle voltage is mapped directly by the controller to PWM - this is what happens internally for both controller throttle and current limiting. The controller processor is just getting the input from a different source and there is no intrinsic electrical delay using the throttle input. The internal controller processor loops through its main control loop at the same speed, sampling current and throttle - one input is as good as another. If you want to argue that some controller uses a non-uproc full-analog feedback control to link current to PWM, then sure - it may be smoother - but the period of delay in the uproc loop is imperceptible in human terms so response speed is no more an issue than it is running normal 'speed' throttle on any conventional uproc-based controller.

If you want to split hairs over milliseconds for differences in main processing loops in an outboard controller (CA V3 or your box) and throttle sampling by the on-board uproc, you are no doubt correct - but the max possible sync delay is the sum of the uproc main loop periods (18msec for the V3, faster for the controller). I'm agreeing that what you say may technically be correct, but the significance of that 'compromise' in terms of drivability is unlikely to actually be meaningful for most.
 
this 18msec .. is this taking into account of adjusting the throttle output to a steady state from the ca after it detects a over current event ?

I have come across controllers that can take longer than that to get from zero throttle upto max throttle without anything on the throttle input.

edit:
Sorry you are just talking about the processing loop time within the ca...
 
As I indicated, this is the period of the main processing loop - just like any PID controller. The various gain settings for the PID coefficients determine the magnitude of adjustment but not the speed of the initial response. If the initial correction is close to the target value, the issue of steady state is of little importance. 18 msec is fairly short from the perspective of 100msec in 1/10second.

Current Throttle is but one part of the V3 capabilities - not the entire focus of the device. Simplifications were introduced to make it more easily tunable, notably, there is only a single gain adjustment because it does not use the conventional PID model. For commercial purposes this is a good compromise for the majority of the market from Grin's perspective. As a result, the initial response although rapid, may be of insufficient magnitude to be perceived on the first loop iteration where a revised algorithm (more conventional PID controller) might otherwise afford a larger initial response and still be able to avoid overshoot or oscillation on the grosser sense. Software at work...
 
I played around with pid control at one point but could never get 100% results what I needed ( but it was very close to perfect ), if I got the initial response what I liked it would oscillate around the set point , maybe it was the algorithm that I was using or more likely delays within the complete system. I would love to try a CA just for this function as I have nothing to compare my system to ( maybe one day one will come my way to have a play with ).
 
I use an Arduino between throttle and controller so that I can set up a fine tuned command curve. Have you think about such alternative?
You could imagine adding other functionalities and feedback analysis...
 
http://endless-sphere.com/forums/viewtopic.php?f=2&t=61004

http://endless-sphere.com/forums/viewtopic.php?f=2&t=61407

this is a work in progress :D
 
Won't zombiess throttle tamer do the job for you? And it has 4 easily accessed adjustment screws so should be easy to change as you ride until you get it set how you like.
2nd thread here

It's something I want as soon as I get my current problems sorted (Lyen controller, Crystalyte's Kenny not answering emails again).
 
the TT solves 80% of the issues and will be more than acceptable for a lot of people, but I would like a 100% fix when using these cheap controllers along with a 5-15kw bike.
 
damn. my middrive is 2.5kw only. now i can't use your controller. and to know that after i ordered all the stuff ....
onlY joking. ;) i guess throttle response can never be good enough and there are some many different ways each one of us prefers his throttle that every new approach is welcome to me.
 
:D the 5-15kw is just a guide.. :mrgreen:

you could have a throttle problem with just 500w it all depends how it is geared .
 
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