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New off-road paraplegic scooter prototype test

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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 10 Aug 2018, 15:56

Sadly your black wheelchair already has a legal definition from its type approval. Obviously you are entitled to call it whatever you want but it won't change how it is viewed by the law.

Any off road buggy has problems, throw a petrol motor in and you can only use on private land with landowners permission or on BOAT's or country roads. Start from electric, limit to 8 mph and you have a class 3 wheelchair. Design from the wheels up and use what is available. Suspension needs to work which takes some designing because of amount of travel needed thus the geometry changes, use mountain bike shocks, preferably air sprung so easy to adjust for weight. Add motor/batteries and drive. Use easily available wheelchair control system (taking the easy option) use the SLM control system to have steering control on front wheels. Make chassis/seat placement easy to fit an air cushion and decent back like a Jay 3. It is not rocket science to get something that can traverse off camber or go up/down steep slopes if the rider is more prone than in a chair. I'm stuck with chin control so options are limited.
I've managed to get down part of a mountain bike DH course, I'd be terrified in a normal chair so the buggy does have big advantages, if I am out in the Lakes where I live if anyone asks, its a wheelchair not a buggy or atv. The important bit is the legal definition of it being a wheelchair.

It isn't, I can't go indoors with it and if I am working on a mountain bike event which needs an overnight stay I have to take a wheelchair to use in hotel and getting around.
It is just a way of sticking within the law, being able to use its classification to get where you want to be but it can only do so if classed as a wheelchair. I'll not argue with that if it gets me to the top of a fell :)
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 10 Aug 2018, 16:23

The class 3 law does not diferentiate between internal combustion, steam, electric, or dilithium crystals. And nobody gives a monkeys about legal definitions anyway. But ignoring that. Do you realise that an 8mph wheelchair is a wheelchair. And an 8mph scooter is a scooter. The difference is the way they steer. And both are class 3 invalid carriages as defined by law even if powered by magic. (and only if it has a rear view mirror which no wheelchairs ever do in reality that I ever saw)

The law doesent call class 3 mobility vehicles wheelchairs either. Because not all are, like your scooters. It calls them invalid cariages collectively. Covering wheelchairs, scooters and buggies. Go read the gov page. It doesent determine what powers them either. And it doesent care. Rubber bands, or a diesel engine. The reason wheelchairs use batteries is that a diesel engine would be unwelcome in the pub. But batteries are rubbish. And hopeless off road where a quiet petrol engine is lighter and better altogether. So why use batteries at all since it doesent zero turn or go inside like a wheelchair? Unless forced. But that doesent make it any more or less a group 3 buggy.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 10 Aug 2018, 17:02

Class 3 also requires lights and a few other weird things like a max width of 85cm. The only time anyone cares whether it is legal is if you hit someone and they take legal action. At that point you want your wheelchair to conform, or scooter if that is what you call it. My invalid carriage does what it needs to and in certain aspects does more than a wheelchair and in others like indoors is inferior to a traditional wheelchair. Oh, the Boma is supplied with a mirror which probably never gets fitted :)

Swapping to LiFeP04 batteries was interesting as you can increase max speed past 8mph thereby taking it outside the legislation. Who would ever know.

I've Google'd and can't find any website defining wheelchairs by there steering system but mine uses a wheelchair control system to steer. The definition from Encyclopaedia Britannica is quite interesting https://www.britannica.com/technology/e ... wheelchair as is the Wiki on powered wheelchair.

At the end of the day we'll call them whatever we want, my only concern is having something to get further than a traditional power chair the method used to steer it isn't important as long as it goes where you want.

There are some quirks using a wheelchair control system, decelerating down a steep slope, pulling joystick back to neutral and the park brake cuts in after whatever delay you set and the chair skids. That gets me everytime.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 10 Aug 2018, 17:13

The problem with trying to use a wheelchair system to drive a scooter is that the whhechairs use tank steer. And a scooter cannot. So if you push the joystick laft, then you go nowhere, dont turn or move, while burning up the motors with 100 amps of valuable battery power to each drive motor in opposite directions. So while it can be used its rediculous to do so. And it does this at every single steering input. So to fit a conventional powerchair controller to something that does not use casters is going to fry the motors, run into heat rollback problems and drain the battreries in short order. So yu cant use a wheelchair control system as its *not* a wheelchair!

Whats needed is either a tiller or steering wheel, or a special hybrid controller as used on some cross scooter/wheelchairs like the myra. Those make a scooter work with a joystick without the burned up motors and dead batteries. Those take a stock controller for a wheelchair, and modify them by the control system manufacturer so that they use both channels as a single output channel for drive for a scooter and a seperate servo for steering. And an servo/actuator controlled by the steering input to save the user needing a tiller. Those are complicated and very carefully programmed to work with steering or powered caster steering 360 degrees, need specific adaptations to the control system and are very uncommon.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 10 Aug 2018, 17:46

The Boma uses a DX system with one motor driving the rear wheels and an SLM module which drives a servo connected to each front wheel. I don't see how this can fry the motor?. No diff so you do get a rear wheel speed difference when turning which isn't perfect. Using a wheelchair control system makes sense if setup like that as you can use specialist control like chin joystick or proportional head, I tried non proportional head and it wasn't much fun.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 10 Aug 2018, 18:38

That is a hybrid system. It doesentwork on a wheelchair. Its a custom build thing by dynamic.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 10 Aug 2018, 18:58

It uses standard DX parts and the Wizard software although I have to admit that the servo steering is a nightmare to understand. Maybe they modify the output so it works on a single motor rather than try and do it in the software. Saying that neither Molten Rock who built it or Dynamic Controls could find why it wouldn't pull away with steering lock applied and it turned out to be a restrictor plate in the joystick.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 10 Aug 2018, 19:09

It uses standard DX parts and the Wizard software although I have to admit that the servo steering is a nightmare to understand. Maybe they modify the output so it works on a single motor rather than try and do it in the software.


Those are not standard wheelchair parts, and wont work on a wheelchair. And yes its factory modified to work as a scooter with servo steering. With a small internal change and modified firmware.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 11:11

I don't think that it is modified, there is definitely no custom firmware and Wizard is the standard version you can download. I'll check with the company that bought the design after Molten Rock went bust but I don't think it was a custom setup for them, far too few Boma's made. Definitely standard joystick interface and settings as I had a Mo Vis micro wheelchair joystick on it at one point. It probably has more mountain bike parts than wheelchair.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 11 Aug 2018, 11:19

So when you turn left, one rear wheel tries to reverse and one tris to go forwards? And because that doesent do anything the motors are then loaded up by the inbuilt motor load compensation and around 100A flows to both motors in opposite directions? Hopefully not! Or does it have 1 rear motor. In which case the output stage must be modified as you cant just connect both outputs to one motor.

And how does the steering work? Presumably its either connected to a module and the signal is sent actuator style? Which definitely isnt a stock setup? Something custom or modified (a special power module or something?) somewhere.

In other words I cant see any way to use a stock wheelchair Dynamic or PG module to work one rear drive motor, and a steering servo.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 12:04

One motor using this https://dynamiccontrols.com/sites/defau ... MBS%29.pdf and uses the Dynamics SLM module which is a standard wheelchair part from them and is fully supported in Wizard. So definitely wheelchair control system without modifications.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 11 Aug 2018, 12:57

Dont see how. And if it is, you are only using one channel unless its isnt a stock power module. And how is it steering?

Send me your settings file please so I can have a look.

Heres to problem. Its a dual channel tank steer algort\ythm power module. 2 seperate outputs, intended for tank steer wheelchairs. So you cant connect both outputs together without smoke and internal fighting. Without modification. In the same way that there are SINGLE CHANNEL versions of the roboteq controllers that use the same hardware but are linked internally and use different firmware.

Bacause otherwise every time you turn left or right you will speed up or slow down!

And how is the turning signal controlling a actuator? It doesent do that. It controls the two outputs, and increases power to the left as it increases power to the right. And so you cant connect both to one drive motor. Or one!

There are some chairs that get around this by conecting both outputs to a single 4 pole motor, and these are then not directly connected. But have 4 power wires per motor such as the myra. And an invacare one. But these are not stock power modules, they are different in firmware.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 14:41

A Dynamic Controls PMB-S is a single output power manager, it is not rocket science to offer a single output it connects to a servo module to steer, see page 8 of the link pdf above. If you can't work it out from that I don't know what more I can say, it is simple enough for me to understand with virtually no knowledge of wheelchair control systems.Attached screen shot of the page if you can't be bothered to look at the pdf.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 14:44

That is exactly how the Boma is built just using wheelchair controls nothing custom or special just standard Dynamic parts.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 11 Aug 2018, 17:39

Its a special part. A DX-PM is the usual part fitted to the majority of powerchairs with two outputs, and tank steer mixing etc.
A DX-PM S is a special module customised by internal modification and special firmware (the S stands for Single output) and it wont work on a wheelchair.

In the same way as the Roboteq 2450 that is dual channel, and the Roboteq 2450S is modified to link the two channels safely as a single channel unit with double he power output.

The S versions of both controllers have been adapted to link both the channels together. You cant do that with a normaal wheelchair controller as smoke will come out. This was in response to there being no suitable controller for servo steered scooter like devices. PG have as S one too.

All of them are dual channel powerchair modules adapted to join the two channels together for running one drive motor and one servo steer motor like a scooter And they will not work on a powerchair any longer.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 17:54

It is a standard production part as is the servo, Dynamic obviously see it as a wheelchair part as the diagram above has wheelchair battery clearly labelled. Dynamic also do a range of scooter controls separate from the DX wheelchair.

It is difficult to see how you could fit a front wheel steering system using the servo and single motor onto a traditional wheelchair chassis so I have no idea why they produced this in the wheelchair product range but they did. Possibly there are other companies building in a similar way to Molten Rock did but there must be demand from somewhere for Dynamic to make it.

Anyway, it exists and is being used and can be configured on the Wizard software and I am still no further forward solving the park brake skidding problem :)
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 11 Aug 2018, 18:01

It is a standard production part as is the servo, Dynamic obviously see it as a wheelchair part as the diagram above has wheelchair battery clearly labelled. Dynamic also do a range of scooter controls separate from the DX wheelchair.


Of course it exists. It also exists in the ranges of other manufacturers too. But its an ADAPTED dual channel wheelchair unit in all these cases, produced by the demand for servo steered single motor devices or which there are now a good few. Which is why you need to bridge the two LEFT and RIGHT outputs. As shown. And it exists because a scooter controller has no means of driving a servo for steering. Its purely single channel. If you fit it to a normal wheelchair it will not work even if it looks identical because the output channels have been bridged, and it uses different firmware...
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 11 Aug 2018, 18:44

Good, it seems that we are agreed that these units exist and can control one motor and a servo and this is how the Boma works. I'm happy that we cleared that up.
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Re: New off-road paraplegic scooter prototype test

Postby ex-Gooserider » 14 Aug 2018, 03:29

Note that our programmers and software are NOT the same as the firmware inside the controllers - all the programmers do is set parameters that are used by the internal firmware...

Thus it makes sense to me that the programming software is the same - though I'd be surprised if you didn't either get a different set of parameters to adjust, or possibly some settings that would simply be ignored...

In terms of legal - in the US under our ADA the key definer of a 'personal mobility device' is that it is something used by a person with a disability - regardless of what it is, size, modifications or lack thereof, etc... If you have a disability, they MUST allow you to use any device you need as long as it is safe to do so (no internal combustion inside for example) and can be done without endangering others or the surroundings (no 4-wheelers on a single track trail) - however reasonable rules can be imposed when they have a legitimate cause - i.e. walking speed only.... There are very strict rules about how much they can ask regarding your disability and why you need device X, essentially they have to take your word for it unless they see reason to doubt it... The burden is also mostly on the business to justify any restrictions or prohibitions...

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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 14 Aug 2018, 12:41

ex-Gooserider wrote:Note that our programmers and software are NOT the same as the firmware inside the controllers - all the programmers do is set parameters that are used by the internal firmware...

Thus it makes sense to me that the programming software is the same - though I'd be surprised if you didn't either get a different set of parameters to adjust, or possibly some settings that would simply be ignored...

ex-Gooserider


If you downloaded the pdf I linked to you can see that parameters are still adjusted in Wizard 6 with some values halved or doubled, load current set to 50A but actually is 100A. Like most things RTM before attempting to change anything especially on a system that differs to a traditional chair. If you really want to see how different the steering parameters with an SLM are almost impossible for me to understand.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 14 Aug 2018, 17:08


If you downloaded the pdf I linked to you can see that parameters are still adjusted in Wizard 6 with some values halved or doubled, load current set to 50A but actually is 100A. Like most things RTM before attempting to change anything especially on a system that differs to a traditional chair. If you really want to see how different the steering parameters with an SLM are almost impossible for me to understand.


Because its a kludge to modify a stock powerchair dual channel controller to work as a single output device like a scooter controller by removing tenk steer and connecting its 2 channels together and to shift all the mixing etc to a steering servo output. In a way it wasnt really ever designed to do. Its a fix or modification to fill a gap in the market for some oddball servo steered single channel devices.
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Re: New off-road paraplegic scooter prototype test

Postby MichaelB » 14 Aug 2018, 18:37

The power output is the easy part, the servo has to be adjustable for numerous different steering systems and has a lot more parameters because of this hence the complexity of it. With DX they must have had to add a lot of additional parameters into Wizard. Obviously a big enough market to make it worthwhile. Interestingly Dynamic had my chair to resolve a problem where it would not pull away with steering lock applied, it was only when I tried a Mo Vis joystick that we discovered that the problem was a restrictor plate in the DX joystick preventing movement. Dynamic had not realised that this was the problem as it is so different to a standard control setup.
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Re: New off-road paraplegic scooter prototype test

Postby Burgerman » 14 Aug 2018, 18:49

The wizard software is designed to cover every system they sell/sold, including things like brushless controllers, and different seating, lighting modules etc over the years. It just pulls up the correct file and parameters depending on the modules in the system when connected. For what its worth the version 5 is identical but not as modern as in not specifically designed for windows 8 and up. But it works fine regardless once you choose to run as administrator, and is just as updated with relevant info as version 6.

But we have a version 5 with a huge advantage. It doesent require a dongle, so we can access user, advanced (oem) as well as service level which goes beyond OEM and allows many important options that even the OEM wizard cant do...
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