Meyra Optimus 2 15km/h direkt/drive

Power wheelchair board for REAL info!

POWERCHAIR MENU! www.wheelchairdriver.com/powerchair-stuff.htm

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 23 Apr 2022, 14:42

This is all on off meyra scooter software and special programming software for the single channel version of the normal r-net power module. So none of it makes much sense to me or likely anyone else apart from myra.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 29 Apr 2022, 17:17

Burgerman wrote:This is all on off meyra scooter software and special programming software for the single channel version of the normal r-net power module. So none of it makes much sense to me or likely anyone else apart from myra.


Thx BM, i feared it


Hello everyone,

I've made good progress with the adjustment of my Optimus2 and so far I'm happy with it. At next, I'd like to improve the unstable rear.
Is there an Optimus rider, who has experience with that tail breakout and servo adjustments? Or does anyone have any idea where I could start? (see Picture)

Image

I still have a completely different question:

My Optimus makes a ticking noise - it comes from the left front-wheel. It is dependent on speed. The noise gets faster with acceleration. If i drive a little bit back and forth, the noise goes away. Do you have any idea what it could be?

Pierro
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 29 Apr 2022, 17:30

I've made good progress with the adjustment of my Optimus2 and so far I'm happy with it. At next, I'd like to improve the unstable rear.
Is there an Optimus rider, who has experience with that tail breakout and servo adjustments? Or does anyone have any idea where I could start? (see Picture)


Its not as unstable as rear casters, but its still rear steered. You are attempting to defeat physics. Its not actually possible.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 29 Apr 2022, 17:46

Burgerman wrote:
Its not as unstable as rear casters, but its still rear steered. You are attempting to defeat physics. Its not actually possible.



In my mind it could be like the power steering on a car. Steering becomes heavier as speed increases. I'm not expecting miracles, but an improvement. banghead
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 29 Apr 2022, 17:48

Its not as unstable as rear casters, but its still rear steered. You are attempting to defeat physics. Its not actually possible. Myra did as much of this as they were able already. Its the same problem that all rear steered or rear caster vehicles have.


In an attempt to fix this the rear steer you need super fast servo response an super fast and more accurate gyro response. Those things are out of your hands. So the corrective response comes too late and it causes it to overshoot. Hence your tail swinging problem. It can be made better but not by programming but much faster and higher resolution hardware. No amount of fine tuning or increasing gain that is software sat above the hardware can fix that. Only make it feel slightly different.

We discovered this with model helicopters tail rotor gyros many years ago. They now cost us a fortune because the servos and gyros have to be super fast and ultra high resolution in order that gain can be turned up high enough or they just "hunt"... And do so too late.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby LROBBINS » 29 Apr 2022, 18:24

Another parameter that may help with the "groundloop" tendency may be available; it is on some controllers but I don't know about yours. This is a parameter that reduces turn rate response. So, for example, it can be set to give full turn rate at 0 speed and 50% turn rate at full speed. As Burgerman said, having the steering wheels aft of the CG is intrinsically unstable so, no matter how quick a gyro or what other parameters can be adjusted, there will be circumstances, such as on wet leaves, where that rear end will breakaway. There is a saying among pilots of tail-wheel aircraft: "There are those who've done a ground loop and those who will".
LROBBINS
 
Posts: 5543
Joined: 27 Aug 2010, 09:36
Location: Siena, Italy

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 29 Apr 2022, 19:02

That setting is under general, front wheel drive, and is a rate of FWD as a percentage. And an acceleration percentage.

They dont work well because when traveling in a straight line you do not want response reduced. When traveling and then turning slightly its natural unstable platform accelerates the turn in a very steep curve and so increases the percent of turn acceleration and rate, all by itself. Now you do want it. And actually need NEGATIVE turn input. Which the gyro does for you but by the time the steering servo has corrected the turn its all too late. And adding more gain just causes overshoot. It also takes away the USERS input as all the power is already being used up.

So generally this is disabled or set very low, and the gyro takes over. And then you are relying on gain and resolution and the slow servo steer response.

The obvious real solution would be to turn the seat the opposite way, and run the thing as a rear drive front steered device and disable all stability/front drive/gyro etc so it steers in an accurate stable way that inproves as speed increases. Instead of the opposite.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 29 Apr 2022, 19:45

I understand what you mean.

Burgerman wrote:
The obvious real solution would be to turn the seat the opposite way, and run the thing as a rear drive front steered device and disable all stability/front drive/gyro etc so it steers in an accurate stable way that inproves as speed increases. Instead of the opposite.



I've thought about turning the seat too. Maybe I'll buy a used craft object to test it out.
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 29 Apr 2022, 20:46

Testing not required. Right now what you are effectively doing is trying to fly an aeroplane backwards. Gyros and electronics can help up to a point but go fast enough and physics eventually wins. Every car on the road is stable and self centering and wants to straighten up. Because the platform is naturally stable. Same with motorcycles. Same with trike undercarriage aircraft, no groundloops. No need to try and use electronics / servos to try o defeat physics. So we already know it works.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby TetraIytic » 30 Apr 2022, 15:11

Turning the chair around looks like the obvious solution. If you do this the steering castor angles will be set on the wrong side of zero. Or to put it another way Drive your chair backwards at 15 km/h as it is now,that's how stable it will be after you've gone to all the bother.
Looking at my old Optimus the angles look fairy unaggressive and maybe adjustable. Just something else to think about.
TetraIytic
 
Posts: 9
Joined: 15 Mar 2022, 13:42

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 30 Apr 2022, 16:13

Cant they too be turned 180?
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby TetraIytic » 30 Apr 2022, 16:49

Well that would be a good starting point. Has anyone done it? The weight distribution will be different on the steering. Dr.s of hard sums would be able to tell you. Otherwise the physics will let you know after you've done the work.
TetraIytic
 
Posts: 9
Joined: 15 Mar 2022, 13:42

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 30 Apr 2022, 17:34

Theres no doubt about the physics. It will be a stable platform instead of an unstable one as long as the CG resides anywhere between the 4 wheels. Which it obviously will.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby rickystyx » 03 May 2022, 09:20

I know it's the wrong way around for maximum stability but having had the Meyra for some time now I have to say I've never really had a problem with it going where I didn't want it to or its arse end trying to overtake the front end. All in all I do sort of really like the chair. I don't see a way to do an easy swap around of the seating arrangement but it hasn't failed to get me where I want to go although I haven't really tried taking it apart to see if it could be done.
There is one thing I do sometimes curse on it with it being front wheel drive and that is in dusty or gravelly steep inclines where it needs your weight over the drive wheels or the wheels spin and lose traction. I can with difficulty shuffle myself to the front of the seat and try a ballancing act on the front edge but that really isn't easy when the seat is already inclined because of the slope. going backwards up such inclines does work though and yes that problem would be solved by reversiing the seat.
It isn't a bad chair but I do wish it was reversed just because of this one let down.
I may try doing some sort of reverse conversion but to be honest I'd have to have some real motivation to get on and do it.
It is a very comfortable and capable chair even though it is really a scooter and as long as you think of it as such, as it isn't any use as a chair for indoors because it doesn't turn like a "normal" chair but for an out of doors go places vehicle it's pretty good although not perfect.
Would I buy another - well I hope I'll never have to but the answer might be probably not, not because it isn't a good chair but mainly because you can't easily get bits for them. I like to be able to fix my own transoprt (at least my chairs as cars are getting beyond me now) and getting bits for the Meyra is nigh on impossible. They use rnet modules that don't appear in the UK and you can't just swap them out because of the way they have the control module set up. You can't get into all of the control parmeters or at least I haven't found the right one for taking off the speed reduction for the steering which annoys me occassionally since the speed drops as soon as you are not going perfectly straight (obviously to reduce or compensate for the instability of the front wheel drive) but it is set to reduce the speed as soon as the joystick is moved rather than allowing a 5 or 10% movement before the speed reduction cuts in. I'd be very happy if I could solve that one.
Its main advantage is it climbs kerbs etc really well (if it isn't dusty etc) and will happily trog along in a straight line at 10mph but if there is any camber on the road or pavement your speed will constantly drop because of the damn steering speed reduction thing.
I love the comfort and the suspension but it isn't a perfect chair - if you are happy trogging along at walking pace then for an outdoors scooter that looks like a chair and folds like a chair then it isn't bad really.
ottobock b400 150Ah lifepo4
Swiss-trac manual chair add on with 30Ah Lifepo4 (want more 15Ah headway cells )
Meyra Optimus (PRIME)2 150Ah lifepo4 :0)
rickystyx
 
Posts: 368
Joined: 27 Jun 2019, 08:44
Location: Morecambe uk

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 03 May 2022, 11:55

Send me your settings file. Let me see if I can make any sense of it.

I doubt it however because it isnt a standard dual channel 120A x2 module. And it connects to a myra made modle that deals with the steering. Its a little like the permobil problem. Its a custom made unit with custom firmware to operate as a single channel scooter module. One power output by combining both L and R channels to drive a single drive motor.

What happes if you set all 3 advanced gate shaping settings to 100.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 04 May 2022, 10:13

rickystyx wrote: You can't get into all of the control parmeters or at least I haven't found the right one for taking off the speed reduction for the steering which annoys me occassionally since the speed drops as soon as you are not going perfectly straight (obviously to reduce or compensate for the instability of the front wheel drive) but it is set to reduce the speed as soon as the joystick is moved rather than allowing a 5 or 10% movement before the speed reduction cuts in. I'd be very happy if I could solve that one.

That's what bothers me a lot too. As soon as I drive into a curve, the speed is reduced enormously. I'm also looking for the right parameters. That has to be prevented?


Hi All,

when I got my Optimus delivered, I immediately complained about the restless rear end and asked for an improvement. Meyra played me an improved driving program, which I now have.

You can't imagine how much worse the chair drove then. For example - Meyra set the Tremor Dumping to 80%. I decided to buy a B-dongle. Unfortunately it was only an A-dongle, but with help from here I found out that everything can be set with the A-dongle. Now I know how and I'm glad I can. No more help from Meyra, which isn't one.

I love my Optimus. Once the warranty expires I'll have serious thoughts about converting to a scooter.
Image
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 04 May 2022, 10:20

I love my Optimus. Once the warranty expires I'll have serious thoughts about converting to a scooter.


But it is a scooter.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 04 May 2022, 11:12

Burgerman wrote: What happes if you set all 3 advanced gate shaping settings to 100.

I'll try it.
Burgerman wrote:But it is a scooter.

Thats right. i meant turning the seat into a forward moving scooter. czy
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby fight2repair » 05 May 2022, 20:48

Hey everyone. PIRG - the Public Interest Research Group - is doing an (anonymous) survey of power wheelchair users on their experience getting service and repair of their wheelchair. Could you take a minute and answer a few questions? Your responses will help us with a forthcoming report on barriers to wheelchair repair and servicing. The link to take the survey is: https://forms.gle/HhmKQHRaDsDWM5v8A

Thanks!
fight2repair
 
Posts: 4
Joined: 13 Apr 2022, 03:02

Re: Meyra Optimus 2 15km/h direkt/drive

Postby rickystyx » 10 May 2022, 09:30

I'll get my settings to you when I'm home again BM I'm away for a few weeks and without the computer connection I can't send anything
Cheers
Ricky
ottobock b400 150Ah lifepo4
Swiss-trac manual chair add on with 30Ah Lifepo4 (want more 15Ah headway cells )
Meyra Optimus (PRIME)2 150Ah lifepo4 :0)
rickystyx
 
Posts: 368
Joined: 27 Jun 2019, 08:44
Location: Morecambe uk

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 10 May 2022, 11:30

No rush. I was just curious. Dont think theres a way to fix it.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 10 May 2022, 17:37

Burgerman wrote:In an attempt to fix this the rear steer you need super fast servo response an super fast and more accurate gyro response. Those things are out of your hands.


You are right BM. These things are out of our hands.

I think the origin of the problem with the unsteady rear is because the steering rear wheels follow the bumps in the ground. Also, bumpy tracks can mean that you accidentally make steering movements on joystick that you don't want. Once the steering wheels are out of control, the journey has to be slowed down sharply in order to catch the rear end again.

My idea is to make the steering more stiff at higher speeds. As it is with the car Power steering. So that the steering wheels at least have a better directional stability and are not so easily diverted from the path.

I think here is an improvement to find:
Image
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Pierro » 10 May 2022, 18:14

Hi @all,
can anyone imagine something under this section?
Image

PS: I would like to apologize for my poor English. I always have to have everything translated.
My dream: drive a self-made power chair with a lot of power and high speed. For infinite range.
User avatar
Pierro
 
Posts: 72
Joined: 06 Nov 2014, 12:37
Location: Germany, Hessen, Fulda

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 12 May 2022, 00:52

Well its a lot better than my german!
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby ramboo73 » 24 Jul 2022, 09:31

Hello. Wheelchair Meyra Optimus 2 R-net. Recently, such an error has begun to appear. Tell me where to look for the problem.
Attachments
4dceeba8-27bf-4d1b-9a93-5f3ec2e8d03d.jpg
ramboo73
 
Posts: 9
Joined: 19 Dec 2020, 14:07

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 24 Jul 2022, 10:11

That chair does not use a normal R-Net system. Its a single channel scooter style drive version of the r-net power module. It is used with custom Myra electronics, and custom Myra servo motors and feedback system. In many ways its the same problem we see with all the permobil chairs. As the The fault is in the Myra parts of the system. So you will need to contact them for more info on those myra made bespoke parts. Nobody else knows much about them. The R-Net system is just reporting this error not a part of it.

I would check the wiring to the myra parts of the system, from that to the servo motors on the casters. Which are not actually casters but steering wheels... And check the feedback pots/encoders/or whatever they are using on these steer wheels very carefully. And the servo motors themselves. You will need some basic electronics skills and a multimeter.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby rickystyx » 24 Jul 2022, 10:13

Connection to the servo motor on the rear of the chair or the connections to the freewheel lever mechanism
ottobock b400 150Ah lifepo4
Swiss-trac manual chair add on with 30Ah Lifepo4 (want more 15Ah headway cells )
Meyra Optimus (PRIME)2 150Ah lifepo4 :0)
rickystyx
 
Posts: 368
Joined: 27 Jun 2019, 08:44
Location: Morecambe uk

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 24 Jul 2022, 10:19

Could be either of those, but less likely to be the freewheel lever as thats not a part of the myra system. As per error code? Unless it interupts that connection to the servo motor. Possible. But why would they do that. Normally it interupts a brake solenoid wire.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

Re: Meyra Optimus 2 15km/h direkt/drive

Postby ramboo73 » 24 Jul 2022, 10:23

I noticed that this error appears when I stop on an uneven surface.
ramboo73
 
Posts: 9
Joined: 19 Dec 2020, 14:07

Re: Meyra Optimus 2 15km/h direkt/drive

Postby Burgerman » 24 Jul 2022, 12:01

That doesent help. Because nobody knows how their system works or why that would matter.
User avatar
Burgerman
Site Admin
 
Posts: 65050
Joined: 27 May 2008, 21:24
Location: United Kingdom

PreviousNext

Return to Everything Powerchair

Who is online

Users browsing this forum: LROBBINS, woodygb and 100 guests

cron

 

  eXTReMe Tracker