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R-Net.

Postby Burgerman » 22 Feb 2018, 00:24

When my newchair arrived I reprogrammed it before even sitting in it after looking at the daft settings. But one thing I noticed was that it was configured as a front wheel drive chair. On a rear or mid drive this should be set to 0% or OFF if you prefer. Mine was set as default to 50%.

Out of interest I just reset it back to 50, how it arrived. And it feels horrible! Drives all weird. So I suggest that anyone using a rear drive chair sets the Front Wheel Drive to 0% just in case its been inadvertently set incorrectly by the manufacturer. And this is not the only time I saw this. And the same thing on other software. Disable FWD mode...

Its designed to do funny things with your input commands to try and make a front drive chair steer properly. And not be over sensitive to steering at speed. And it feels horrible unpredictable! It also makes things not linear at indoor speeds too while you try to accelerate or decelerate as you turn. The amount of forward acceleration/deceleration you get is changed by how much turn you use. Yukky and unpredictable. For what its worth its one of the things that makes chairs like the F5 and other chairs that are front drive feel odd and drive a bit funny. But on those theres no choice. They are trying to fight physics with software.
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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 00:37

From the r-net manual:

11.11 FRONT WHEEL DRIVE TYPE
Front Wheel Drive Type selects specific specialist software for front wheel drive wheelchairs
If Front Wheel Drive Type A, this parameter electronically alters the shape of the joystick gate. This has the effect of damping the turning rate of the wheelchair between the 9 o clock and 3 o clock joystick positions.
If Front Wheel Drive Type is set to B, this parameter sets threshold which, if exceeded, then both forward and turn speeds are reduced, but the turning radius of the wheelchair remains unchanged. Type B can be used to increase the steerability of the wheelchair at speed.
IGNORE THIS IT WONT BE USED

11.12 FRONT WHEEL DRIVE
Front Wheel Drive adjusts the operation of the specialist software for Front Wheel Drive Wheelchairs.
This selects specialist software for front wheel driven wheelchairs.
The programmable range is 0% to 100% in steps of 1%.
If set to 0%, then “normal” software for rear wheel driven wheelchairs is employed. MINE WAS SET 50% AS DELIVERED NEW!!!
If set to any other value then front wheel drive software is employed. A higher value makes the software more suitable for faster wheelchairs.

11.13 FWD ACCELERATION LIMIT
FWD Acceleration Limit sets the limit of forward acceleration when exiting a turn.
This limits the forward acceleration of the wheelchair when straightening out of a turn and helps prevent loss of traction.
The programmable range is 0% to 100%.
IGNORE THIS IT WONT BE USED NOW EITHER
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Re: R-Net.

Postby steves1977uk » 22 Feb 2018, 01:33

Amazes me that manufacturers can't program their chairs correctly! czy :cussing

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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 01:45

I suspect that they used a 120 power module (normally 90 acc to rover) that they copied a front drive program in error.
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Re: R-Net.

Postby snaker » 22 Feb 2018, 01:53

What would happen if this fault happens to a ... car :cussing

I am curious if in EU, a car manufacturer sell cars with the same fault to customers, are they punished?
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Re: R-Net.

Postby expresso » 22 Feb 2018, 02:24

What section is that - i like to check my settings also - curious how mines was set from factory
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Re: R-Net.

Postby expresso » 22 Feb 2018, 02:31

found it -

this is how mines arrived and still is -


also today went out for 20 mile ride and i lost one green bar -- the changes i made to the battery as you suggested maybe works to some degree

cant recall when i lost it - how many miles i done - since i didnt expect it
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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 02:40

Well its set wrong then. And will drive worse. Not much, since the other part below is set to zero, but you have the wrong joystick setting.

If Front Wheel Drive Type A, this parameter electronically alters the shape of the joystick gate. This has the effect of damping the turning rate of the wheelchair between the 9 o clock and 3 o clock joystick positions.
So if the Front Wheel Drive setting is zero, this is ignored. So set from 70 to 0 and test.

Seriously, how many chairs are out there set badly?
Other than this, my motor compensation was overly aggressive, reduced from 45 to 40. And all the full and minimum turn acceleration / deceleration settings were rediculously low! And turn rates were too high, and forward and reverse DECELERATION throws you forwards and almost out of the chair. Those currently set way lower to 10, inc minimums.

Why cant they get the basic configuration anywhere close?

What did you set battery calibration to? Whatever it was, do it more. I am not sure if that will set just the gauge at the top. Or across the board.
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Re: R-Net.

Postby expresso » 22 Feb 2018, 02:55

according to what you posted -

i can set it to B instead of A - but it will be affected in other ways then - not sure which would be the better - -

the other is set to 70 which states higher is better for faster speeds -


the battery cable i believe i set it to %140 from the stock %100 -

i should raise that to about %160 and look out for it -

seemed strange to see one green light go out - makes me worried :) that wont affect the chair in terms of making it stop ? just an indication ?
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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 02:58

The A or B is IGNORED if you set that 70, to zero. That turns all 3 front drive settings to OFF.

Setting 70 is better for a FRONT DRIVE chair that is fast. Its the opposite to you. Set to 0 and test.


Setting to 70 adds damping (delay) or reduces turn rate at speed. Because a front drive chair would start fishtailing or spin... It affectively prevents the turn you want from happening when going fast. A rear drive chair is overly stable. So yu need the opposite. Which is why the manual says turn it off.

>>just an indication ?

Hopefully! We can only test. Its called battery guage calibration. So shouldnt affect anything else. :problem:
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Re: R-Net.

Postby expresso » 22 Feb 2018, 03:08

Ok so i need to just set it to 0 and leave the rest alone -

wont be going out anything soon - but i will change it and try it slowly at first -

just change the 70% down to 0 - and thats it ?
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Re: R-Net.

Postby sin85 » 22 Feb 2018, 06:12

Burgerman wrote:From the r-net manual:

11.11 FRONT WHEEL DRIVE TYPE
Front Wheel Drive Type selects specific specialist software for front wheel drive wheelchairs
If Front Wheel Drive Type A, this parameter electronically alters the shape of the joystick gate. This has the effect of damping the turning rate of the wheelchair between the 9 o clock and 3 o clock joystick positions.
If Front Wheel Drive Type is set to B, this parameter sets threshold which, if exceeded, then both forward and turn speeds are reduced, but the turning radius of the wheelchair remains unchanged. Type B can be used to increase the steerability of the wheelchair at speed.
IGNORE THIS IT WONT BE USED

11.12 FRONT WHEEL DRIVE
Front Wheel Drive adjusts the operation of the specialist software for Front Wheel Drive Wheelchairs.
This selects specialist software for front wheel driven wheelchairs.
The programmable range is 0% to 100% in steps of 1%.
If set to 0%, then “normal” software for rear wheel driven wheelchairs is employed. MINE WAS SET 50% AS DELIVERED NEW!!!
If set to any other value then front wheel drive software is employed. A higher value makes the software more suitable for faster wheelchairs.

11.13 FWD ACCELERATION LIMIT
FWD Acceleration Limit sets the limit of forward acceleration when exiting a turn.
This limits the forward acceleration of the wheelchair when straightening out of a turn and helps prevent loss of traction.
The programmable range is 0% to 100%.
IGNORE THIS IT WONT BE USED NOW EITHER


Thanks for that as I will be using those settings since my chair (or as you call it scooter) is FWD . cheers
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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 12:01

just change the 70% down to 0 - and thats it ?


Yep.
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Re: R-Net.

Postby expresso » 22 Feb 2018, 17:42

Done - made the changes - the battery part can only go up to 150% so thats about it - i had it at 140 - and i lose one green bar around 18 mile mark i believe - will keep an eye on that the next time - wont be for a while since it got cold again - and i tested a new camera i got - seems to work nicely so will keep it and maybe get another for the other change - was cheap enough at $60

https://smile.amazon.com/gp/product/B01 ... UTF8&psc=1
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Re: R-Net.

Postby Gnomatic » 22 Feb 2018, 18:04

expresso wrote:
also today went out for 20 mile ride and i lost one green bar -- the changes i made to the battery as you suggested maybe works to some degree



What was it you changed?
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Re: R-Net.

Postby Burgerman » 22 Feb 2018, 18:51

Under battery, set the calibration to 150.
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Re: R-Net.

Postby steves1977uk » 22 Feb 2018, 20:50

This can also apply to Pilot+ systems with full lithium conversion. :thumbup:

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Re: R-Net.

Postby Burgerman » 23 Feb 2018, 02:31

Yes
FRONT DRIVE on/off - however I never saw a pilot plus set incorrectly.
and
BATTERY CALIBRATION setting to 150.
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Re: R-Net.

Postby expresso » 23 Feb 2018, 03:34

Burgerman wrote:Yes
FRONT DRIVE on/off - however I never saw a pilot plus set incorrectly.
and
BATTERY CALIBRATION setting to 150.



actually i think mines is that way set to FWD on my pilot also - i have to double check
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Re: R-Net.

Postby expresso » 23 Feb 2018, 03:51

yes mines is set to FWD is ON - on my Pilot Plus chair also - i have to change them also now -

i wonder how it will feel after the change on my Rnet and pilot chair -
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Re: R-Net.

Postby Burgerman » 23 Feb 2018, 04:03

It is hard to quantify. It just feels more predictable and linear. You get the response you are expecting.

FWD ON means that moving the joystick forwards and backwards changes what the steering does, adds damping and reduces turn rates in some positions. And it limits forward acceleration and turn acceleration if you try to accelerate as you turn. So it means that your turn and throttle affect each other. They no longer do exactly as you expect in each case.

FWD OFF means that all the turn settings, turn speeds, and turn acceleration/deceleration stays exactly how you set it regardless of the speed or throttle position. It also means that the speed or throttle stick position has no affect on the amount of turn you choose. In other words the two controls work in linear predictable fashion and do not affect each other. If your chair is programmed to go, turn, stop, when you say so, then its very obviously nicer and more controllable and smoother. As you will see. You may need to adjust your turn rates at high, low speeds slightly afterwards. But I can feel how much better it steers and manoevers even in my room. It better goes where its told.
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Re: R-Net.

Postby expresso » 23 Feb 2018, 04:26

i am going to change the Rnet now - and will test it on Sat. the pilot - next time i use the chair - i will change that also and let you know how it feels to me
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Re: R-Net.

Postby Es* » 23 Feb 2018, 20:25

I know you despise FWD ferociously, but it suits me really well. How would you program a FWD chair, to be as responsive and unrestrictive as possible (I do realise you'll consider this somewhat impossible, but there's space in the world for different opinions/experiences)?
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Re: R-Net.

Postby Scout » 23 Feb 2018, 20:54

Burgerman wrote:It is hard to quantify. It just feels more predictable and linear. You get the response you are expecting.


I think a lot of that might be just what you've become accustomed to. I know that after a day driving a forkllift (steers from the rear but powered from the front), I have to be more careful driving home in my car.

The transition from car to forklift (difficult for many -- like driving a boat!) MUST be accomplished almost immediately. Mistakes on the forklift cost lives or significant damage to property: in any confrontation, the forklift wins -- even when confronting a vehicle! (I have lifted vehicles that needed to be moved out of the way). If, for example, I'm too close to a dumpster, it is often easier to just PUSH the dumpster out of the way than it would be to jockey the forklift back and forth (while carrying a load) to AVOID the dumpster.

By contrast, the transition back to "car" is one that I take for granted: "I've been driving for decades, it's all instinctive". So, I usually fail to expedite the transition (in my mindset) and catch myself putting the car in situations that I'd not do several days AFTER spending a day on the forklift. E.g., I'd never consider giving an adjacent CAR a "nudge" if I was parked too close to it! :o
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Re: R-Net.

Postby Burgerman » 23 Feb 2018, 20:56

The issue isnt about opinion. Its about physics. You can believe its as good, or as stable or as controllable all you want. But the physics doesent allow that. Its already a careful balance of responsive control and stability. And increasing one decreases the other.

If I were to set a front drive chair up with linear response, and with very fast response (less delay in control) by transfering all the settings I use on a rear drive chair to a front drive one it will be all but uncontrollable at anything over about 2 mph. After this you feel the mass behind the drive wheels trying to push every correction or turn harder than you instructed. It amplifies a turn over time. And so mad fishtailing, and at higher speeds swapping ends altogether, or losing directional control and going into a wall or the road is a real consequence.

With mushy slow controls, and special front drive algorythm that tries to limit motor acc while turning and at speed and add extra turn rate at low speeds this allows some reasonable control up to about 4mph. But it feels decidedly on the edge if you turn tight at speed or if on a slippy surface.

Adding gyro or accelerometers with the latest systems from r-net or Dynamic etc, has allowed them to up this to 6 or 7 mph. Without actually spinning out or fishtailing. It does this by watching the chairs actual angle, compared to the joystick. It measures turn rate programmed against real turn rate. And when in a straight line it prevents fishtailing (mostly) in the same way. And so it adds power or reduces it to each wheel in turns or to stop fishtailing before it gets out of hand. And in the same way it tries to prevent it spinning out at speed. Its akin to throwing a dart or model airplane backwards. Its simply naturally unstable. The computer keeps it "flying" backwards in spite of the chair or plane/dart wanting to spin around. But this uses up the motor power that you may require to manoever or control so frequent inconsistency of response if set to do so. And above x mph or x grip level no gyro can help regardless.

So if for eg you want to turn or correct course left, at speed, the rear of the chair will want to spin out, which tries to make it turn ever tighter than you wanted even after you intended to go straight. It tries to spin 180 degrees. The gyro tells the motors to add RIGHT turn to prevent it spinning left. As long as it doesent exceed the motor torque needed and does it fast enough (which on a chair programmed like mine you easily beat) this works. As long as there is adequate tyre gip. On a winter footpath covered in leaves, on damp grass, snow, you would just spin out of control maybe onto a road or wall. But even where you dont, you can feel the chairs response is taken away from your joystick. It feels funny to drive because of this. The problem has nothing to do with opinion.

If you dont care about any of that and are happy with delayed control, and low turn rates at speed, and a weird feeling front wheel drive special algorythm gives, then front drive is fine. Otherwise its not. Its a compromise you must choose. I tried front supposed fixed modern r-net systems with gyro etc, and to me its not usable beyond about 4mph and that feels funny in regards control absolute predictability. On a puma 40. The gyro does allow faster travel with less fishtailing but you can feel the fight that is going on via the strange inconsistent control responses.
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Re: R-Net.

Postby Burgerman » 23 Feb 2018, 21:00

I think a lot of that might be just what you've become accustomed to. I know that after a day driving a forkllift (steers from the rear but powered from the front), I have to be more careful driving home in my car.


No. A fork lift has directional rear wheel that control the steering. They are not free to overtake you.
A better analogy is to do any of the following.

1. Set your rear drive powerchair so it can go 6mph in reverse. I challenge you to exceed 3 ever without losing control.

2. Fit CASTERS on the rear of a front wheel drive car. Try and drive in a straight line, and better, try turning... Too complicated to do but use your mind!

3. Take any manual wheelchair. Push it across a car park and let go. It will travel in a straight line, even if you attempt to knock it off course it will then straighten up naturally. Now turn it around so the casters are at the rear, do it over again to simulate front drive. As you let go it will try and turn around and go forwards again, every last time. You cannot defeat physics. It will not roll far backwards!
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Re: R-Net.

Postby LROBBINS » 23 Feb 2018, 21:33

A front wheel drive chair is the equivalent of a tail-wheel airplane - both have a swiveling caster behind the center of gravity so inertia acts as positive feedback in turns. The result is a classic of aviation "There are two kinds of tail wheel pilots: those who've ground looped and those who will." As with the gyro stabilization that John described, the tail wheel pilot counteracts the positive feedback by rapid counter-inertia jabs on the rudder pedals which are hooked by springs to the tail wheel (it's not free castering unlike on a chair). The ground loop happens when that rudder pedal dance is not close to perfectly matched to the side forces due to inertia. Some planes have locking mechanisms that can hold the tailwheel straight during take off, but obviously can't be set when steering on the ground.

BTW-my daughter's chair is FWD, but it is driven only very slowly (with a head-switch array) or slowly (with an attendant joystick). There's no gyro, but my own control system and Roboteq script have turn rate that can be set to reduce linearly with speed; I have it set to 50% at full speed. On a surface with a good tire grip I can go 4 mph and feel reasonably comfortable. Max speed is 5.5 mph, but as I can't walk that fast anyway, that's used for only short bursts such as crossing a street, and it feels decidedly squirrely.
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Re: R-Net.

Postby Burgerman » 23 Feb 2018, 21:52

short bursts such as crossing a street, and it feels decidedly squirrely.


Squirrely is what I am trying to explain. Even when a gyro takes over the control of the squirel, it eats into the motor power at higher speeds than 4 or 5mph greatly. And you feel this as unpredictable turn response. As in the gyro is already using the power to correct so not much left for you. Or it already trying to spin that way so the response is better than expected!

Tail dragger aircraft analogy is good. But not as severe, since theres a dirty great vertical fin keeping the rear at the back where its supposed to be. Like a dart. We dont have one on a powerchair! So its worse.

With a fin...

youtu.be/N6jSruMW84Q

youtu.be/i8oqVNgA6fI

youtu.be/3xx0pV_AUQE

youtu.be/mukmCGDvFlQ
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Re: R-Net.

Postby ex-Gooserider » 27 Feb 2018, 07:36

There is actually an outfit in CT that makes systems to put casters on the back of FWD cars... It's a thing they call 'Skid Monster' and is marketed to places that do training for police drivers, "executive chauffeurs" of the bodyguard sort, and others that need to do emergency high speed driving under adverse conditions - the idea is to practice maintaining control with a loose and mobile back end.... Apparently the idea is that the caster system has a locking mechanism that the instructor can turn off. The student gets going with the system locked, starts a turn, and the instructor releases the lock so the fun can begin...

(I'd love to give it a try....)

ex-Gooserider

Burgerman wrote:
I think a lot of that might be just what you've become accustomed to. I know that after a day driving a forkllift (steers from the rear but powered from the front), I have to be more careful driving home in my car.


No. A fork lift has directional rear wheel that control the steering. They are not free to overtake you.
A better analogy is to do any of the following.

1. Set your rear drive powerchair so it can go 6mph in reverse. I challenge you to exceed 3 ever without losing control.

2. Fit CASTERS on the rear of a front wheel drive car. Try and drive in a straight line, and better, try turning... Too complicated to do but use your mind!

3. Take any manual wheelchair. Push it across a car park and let go. It will travel in a straight line, even if you attempt to knock it off course it will then straighten up naturally. Now turn it around so the casters are at the rear, do it over again to simulate front drive. As you let go it will try and turn around and go forwards again, every last time. You cannot defeat physics. It will not roll far backwards!
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Re: R-Net.

Postby Burgerman » 27 Feb 2018, 13:52

The student gets going with the system locked, starts a turn, and the instructor releases the lock so the fun can begin...


He wouldnt need to start a turn. Attempting a straight path is adequate. Unlocking the casters alone will allow physics the chance to massively amplify even a tiny 0.1 degree error in direction accuracy. And then it will try everything possible to end up facing the other way. Especially so, if like a powerchair the drive wheels and driver cannot turn left/right to try to correct things. It will just flip around.

In exactly the same way that you cant throw a dart backwards. Or roll a manual wheelchair backwards. It always spins around and goes pointed end first. Someone should video that! And forwards to compare.

You can attempt to fight this all the time with fancy gyro and waste a lot of battery power trying to defeat physics, but it still feels decidedly egdy or squirrely as lenny says. And go fast enough, or on slippery stuff like winter leaves, snow, wet grass and it will spin out regardless.
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