Forward/Reverse

[urosv]

Hi there,
Small team is working on a small project (trike) and we are using reverse button to change direction. We are using MagicPie3. When using this feature it seems that direction change is not done instantly. There is aprox 1 second delay between fully set the controller to reverse. If you are still having some small speed with throttle there is aprox 60 degree movement of wheel in oposite direction and then it turns to reverse. We tried this on 5 different MagicPie3 motors so we think there is a problem/feature in controller. Is there any explanation for this behaviour. I also think that UniCycle does not have this malfunction

Thanks for any advice or pointing to right direction.

The feature we would like to accomplished is when user presses the button to reverse direction it also triggers the small amount of reverse speed (1-3km/h - walking speed). This we manage to do but like the problem I described it first turns the wheel forward and after a ~60 degrees the correct way.

[Morgen 3Eman]

On my trike the reverse switch changes the direction of rotation from the point the wheel was at when the switch was closed.  However, I only change direction when at a full stop.  Are you changing direction while still moving?  (MP3)  If you are commanding reverse while moving,  my guess is that the wheel has to overcome the inertia before changing direction. 

Are you absolutely sure you want to have no operator control over the speed while in reverse?  It would be fairly easy to accomplish, but I personally think it is a bad idea.  Would you buy a car that you cannot control in reverse except by braking?  Would you advise your 16 year old son to buy one?  Again, just my opinion, but I would not.  I'm interested in knowing why you seek such a feature, if you don't mind telling us.  To actually implement it would require an switch with enough poles to impose a low voltage on the throttle input when selected.  I think Alan recently posted a method for a cruise control inquiry.

TTFN,
Dennis
 

[urosv]

Thanks for replay. You misunderstood me. It has nothing to do with inertia. In your case it is not true that it goes directly backwards. It does that because the time from completely stop and reverse is > 1 second. Regardless what you want or not the "walking speed" is used and controlled from Post office delivery guys and the use it every day. It is not controlleless operation !

[Morgen 3Eman]

I jacked up my trike and took the cover off the rear wheel so I could see what happened and when it happened.

Ok, so here is what my MP3 does with the Pie off the ground. 

If the wheel is still rotating when I switch from forward to reverse, or reverse to forward: 

    The wheel slows from what ever speed it was at, and before it comes to a complete stop the wheel changes direction with a large torque input to the motor.  Or, with no throttle input, the motor comes to a stop, slowing at the same rate as before the switch was changed.  It is my guess that the wheel speed needs to be under some limit before the motor will actually reverse.  The rate of slowing sure looks like inertia  to me.  When switched to reverse just before the motor stopped, there was no apparent change in stopping position from where I estimated, indicating a 60 degree jump.


When I wait til the wheel just stops and then throw the switch with no throttle applied, the wheel does not rotate an additional 60 degrees.    When I give it some throttle at the same time as throwing the switch, the wheel starts moving immediately in the other direction. 

I tested my Pie many times, to ensure I did not induce or allow a "1 second lag".  The results repeated every time.     If I reversed just before the wheel came to a complete stop, (Under the limit I supposed above) the wheel would immediately change direction, again with a large torque pulse.

After watching my wheel react to the switching, I have decided to install torque arms on both sides of the axle.  The torque pulse is very impressive!

Did you search for the cruise control message I wrote about?  I'll tell you just what you need to do.

TTFN,
Dennis
 

[Morgen 3Eman]

If you take a look at the "Giant MTB..." thread, you will find just what you need for connecting a fixed speed reverse signal.  You will have to substitute a potentiometer for the PCB in the drawing.


TTFN,
Dennis