Steering

[davidpaul]

Steering, I see there are a few manufactures who make scooter style all terrain mobility vehicle's with either manual or joystick steering, how would someone make a all terrain manual steering scooter joystick control ? If it's possible

[rickystyx]

it is done using a large servo on most of them

[davidpaul]

Ok, thanks, Would that need a special controller ?

[Burgerman]

Yes.

[davidpaul]

Can I ask if any one knows what make/type of controller I would need

[Burgerman]

R-Net but you would need to get a specific one made up, programmed for single chanel plus steer servo. Speak to pgdt.

Or steal one from a myra or something. They are a one off thing.

[davidpaul]

Ok thanks

[Burgerman]

By one I mean power module.

[davidpaul]

Would the joystick be a standard R-net one ?

[Burgerman]

Yes as far as I know.

[davidpaul]

Surprisingly (not) pgdt wont help, apparently the scooter would require modification and fitting a steering servo ??? and lots of testing that only oem's can do,

[slomobile]

Anyone can do testing. Its just a matter of will, time, and resources. Rnet is not the only option out there, especially in the scooter segment.
Look into robotics development tools instead. I have some experience there and can help if you define the problem a little more.

What is the overall thing you want to accomplish? Ignoring any existing solution, where do you want to go, what are your priorities during the trip?
What equipment to you already have which you want to use?
What is your budget?

If this is too broad and you want a solution to a specific problem, pictures and model numbers always help.

[davidpaul]

My aim is too provide my son with something that will keep up with our little mountain biking group, 3 out of the 5 off us have disability's so we don't do much extreme riding, just want something that would say do 8-10 mph and have a range of 25 miles.
He currently has a v6 powerchair which has been good but 6 mph isn't fast enough, I'm in the process of fitting a 120a control module in place of the 90a one, and also upgrading to 200ah lithium batteries.

I had asked because you can get a 10mph all terrain scooter, but my son would need joystick control, the main problem I have with the v6 is the bloody castor wheels, they keep catching in ruts, the other day he hit a rut and spun the chair around, so looking for something safer without castor wheels, he has other chairs for normal day use, and he will always need help with lifting in and out of the chair which we've always done anyway.

I've modified and even built my son a go-cart out of an old powerchair which was great but still had castor wheels at the front, the other concern is tipping over, my son is a motor sport nut so speed is his thing, i've noticed in recent weeks how much more he enjoys our ride's when is in a group, so that's what I want to achieve.

The chair that caught my eye is one made by Quadrix in France, similar to the Boma but faster and greater range.

I have asked in another post about the Quadrix touch, joystick controlled

[slomobile]

Excellent information about the vehicle purpose. 2 additional questions.
How steep is the maximum grade he expects to ride?
Does he have enough hand/arm strength to use 3 pin steering? That is an adaptive manual steering method that often has handles on both sides, but they are linked so the driver can use either one, or use the remaining combined strength of 2 arms to steer.
https://outriderusa.com/ has some examples. I've spoken at length with their engineer. They are willing and able to adapt to whatever he needs.
If nothing else, these are good examples to copy. They have started a rental program where you can have one shipped anywhere in the world to try it out.

https://reactiveadaptations.com/hammerh ... handcycle/ uses the chest support pad as a means for supplemental steering. If that is a position he can use, they can put electric wheels and a throttle on instead of cranks. Chest pad steering was originally done by Mike Augspurger from One-Off Handcycles (brand name). They are no longer producing, but they put a lot of information about their cycles online to make it easier to reproduce. I think the designer is still answering email.

Most scooters can be converted by adding a steering servo, provided there is a place to mount one. The programming for steering servo is actually easier than wheelchair steering. There is no coordinate conversion. Steering angle is directly proportional to horizontal throw, throttle is directly proportional to vertical throw. Just include a scaling factor to reach the end stops and deadband in the middle. But before you go to all that trouble, just try a stick.

Connect a rod to the tiller which he can manipulate with his hand, or whatever he can move. Adjust the mounting distance closer or further away from the pivot depending on his range of motion. If he has a little function in each hand, one can control throttle, and the other steering. If not, they can still be combined mechanically.

If it were me, I would be looking into something like swerve drive. https://www.swervedrivespecialties.com/collections/kits
Steer all wheels in any direction, and go in that direction. All wheel drive, joystick controlled. This is the type of stuff I used to do in FRC. Needs to be scaled up to larger diameter wheels for outdoors. I think this would help lots of people navigate indoors as it sits. Just add as many modules as you need to support your weight.

[slomobile]

Was thinking about manual steering a scooter with limited range of motion.
Parts:
a twist throttle type scooter,
a ring with setscrew to grip the throttle,
4 ball links https://www.dubro.com/collections/ball- ... ball-links ,
2 control rods (one above one below the throttle),
and a hand grip.

The hand grip he holds in his hand mimics the actual throttle. Twist it, it goes. Push it or pull it, it steers. Move up and down or side to side and those movements are taken up by the ball pivots and ignored. If he cannot push and pull, but can pivot wrist laterally, add 4 more links and 2 more rods to the side of the first set. Now pivoting his wrist also pivots the tiller.

[davidpaul]

Thank you for your reply, Lewis (my son) has cp he has good control of one hand the other thing is his knees have limited movement, so he needs to be in a sitting position with the seat tilted back a bit to help him maintain good posture.
Although he's quite strong we are a bit worried about his ability to control manual steering, he's used joystick control since he was 5y he's 21y now.

Difficult to quantify the steepness, it's steep enough, I wouldn't let him to do it without help

[rickystyx]

I know it's not BMs favourite because it is rear wheel steer but the Meyra optimus 2 is a joystick controlled scooter in a chair format - I find it really good for what I want and it gets me lots of places and importantly will go into my car. Getting control equipment to make your own is likely to be difficult but getting an older Meyra may be an option for you. It has reasonable ground clearance and traction but I will be changing my tyres for something less knobbly so that it puts more rubber onto the ground to increase traction. Only because it is quite easy to get the wheels to spin on dusty stuff - it is great on grass etc

[davidpaul]

Yes we have looked at the Meyra before, just looked at a video on YouTube and it's surprisingly bad on uneven ground, I would say because of lack of flexibility in the chassis, I remember from our enquires before the price go's up fast when adding extras Lewis would need.
Plus I don't think the design is much different from the v6 although there are no castors, I can still see problem with going down hill, that's one thing I like about the Boma design

[ex-Gooserider]

I have been recruited to help a kid w/ a project he is working on as part of an MIT summer course. He wants to adapt an existing electric trike (two wheel steering up front, one Hub-motor drive wheel in the back) for use by a quad, w/ joystick steering...

My suggested approach would be to make a variant of WoodyGB's Arduino RC controller module - use the joystick can out of a pod (the kid has an old Qtronix (rebranded P&G Pilot +) as input to an Arduino, with the Y axis controlling speed via the existing brush motor controller, and the X axis driving an actuator to the steering arm....

Sounds like something similar might be a good solution for this situation as well....

ex-Gooserider

[slomobile]

A Permobil X850 has joystick control and 2 front wheel electric steering also. Wish that were available in US like it is in UK.

[Burgerman]

Other than terrible exchange rates (for you) its easy to buy from the UK. Esp if your communist leader harris, sorts out a free trade deal with the UK in the near future.

I buy all kinds if stuff in the US and Canada, from wheelchair stuff to vans... And hobby stuff like RC equipment. Other than it takes an extra week its no different to buying from my own country or taiwan or hong kong, or australia.

[davidpaul]

I normally only by items that can't be bought in this country, anyway, I had asked Quadrix the name of the controller manufacturer but again surprisingly no response

I would be interested in any project that would allow a joystick to power servo steering, I have seen a picture of someone's project and they used a powerchair drive motor and gearbox to power the steering

[Burgerman]

That setup would necessitate some kind of feedback system or it would stall at full lock and necer be able to be centred.

[slomobile]

Other than terrible exchange rates (for you) its easy to buy from the UK. Esp if your communist leader harris, sorts out a free trade deal with the UK in the near future.

I buy all kinds if stuff in the US and Canada, from wheelchair stuff to vans... And hobby stuff like RC equipment. Other than it takes an extra week its no different to buying from my own country or taiwan or hong kong, or australia.

That is worth exploring. Strange that 3 days ago I drove right past Lebanon TN where Permobils are made, but now I'm contemplating having one shipped from UK. How can an American purchase and ship an X850 from the UK? My DME cannot order it, I cannot order it from the Permobil website. Recommend a good place that deserves the business. Maybe there is a place to order from with cheaper shipping and exchange than UK? Aussie maybe? The Meyra looks interesting.

[Burgerman]

In the UK such things come from shops. Like this one. https://store.easylivingmobility.co.uk/ ... -corpus-3g You order from a real brick built shops showroom. Or online via the interweb. Having never bought such an oddity and always avoided permobil like the plague I cant help. Maybe rover and his bosses can supply? Or maybe ask permobil for their most reliable dealer in the EU or UK.

I would expect to get 20% off, plus whatever it costs to ship from the right dealer.

Also I think they are a nordic country product. But also manufacture in the US.
They are owned by some group called Patricia Industries.

Patricia Industries is responsible for the wholly-owned subsidiaries of Investor AB. Since 2006, the focus on wholly-owned companies has increased significantly. Patricia Industries was established in 2015 to accelerate and increase the commitment to that effort. The focus is to own Nordic and North American companies; the Nordics is our home market and we have been active in North America for decades.

Product development for e.g and most of the permobil design stuff happens in sweden and norway. Which explains their silly pricing. https://career.permobil.com/departments ... evelopment

[slomobile]

I normally only by items that can't be bought in this country, anyway, I had asked Quadrix the name of the controller manufacturer but again surprisingly no response

I would be interested in any project that would allow a joystick to power servo steering, I have seen a picture of someone's project and they used a powerchair drive motor and gearbox to power the steering

Car power window motors or wiper motors are usually sufficient for steering forces and much more compact.

If you are going to build it yourself, you will save a lot of headaches by just using a SyRen or Sabertooth motor controller. https://www.dimensionengineering.com/pr ... rtooth2x60 Don't let the nominal current rating fool you, its plenty. The 2x32 is plenty for most circumstances. I used a 2x 25A on a robotic cart with wheelchair motors to push my Chevy C2500 truck to the alternate side of the street (avoiding parking ticket) when the fuel pump went out. They ship with photographic printed instructions. Great company. Use any analog component or industrial joystick and feed it directly to the analog inputs. Simple, cheap, done.

If you want to get fancy, you can throw a microcontroller like Arduino in the mix, I have code for that if you need it. Differential steering boils down to
LeftWheel = JoyX + JoyY;
RightWheel = JoyX -JoyY;
SteerAngle = ScaleFactor * JoyX;

ScaleFactor is based on the as built geometry. Unicycle models of the math are published all over the place.

Even fancier? Look for autonomous RC cars. https://github.com/NVIDIA-AI-IOT/jetracer is one example.

You can even use a 3 axis joystick with twist if that is easier for him, or a space mouse module, or a trackball.
Narrow down the choices and we can offer solutions. The usual suspects in this domain(steerable wheels) are robotics and mobility scooters, not wheelchairs. But they do exist as well.

[Burgerman]

(avoiding parking ticket) when the fuel pump went out.

Did it go anywhere good?

[slomobile]

(avoiding parking ticket) when the fuel pump went out.

Did it go anywhere good?

well, I took it apart, fixed it and installed it in my parts washer. So it got a change of scenery.

[davidpaul]

Just a thought, why couldn't I use a scooter rear axle and use one power supply from the joystick controller to power the motor for drive and use the second power connection to power the steering servo or motor, so instead of powering two drive wheels use the right motor control for driving and left for steering

[Burgerman]

Because on any normal POWERCHAIR controller the two channels are mixed to provide 120A of TANK STEER power to the motors. So both motors roll when you choose forwards. So doing as you say your steering servo will turn hard one way and half the power will go to a drive motor. When you reverse it will turn hard the opposite way.

If you look at a myra chair it uses a special 120 R-Net module that has completely different programming. BOTH 120A channels are drive forwards and backwards only, with no tank steer. Because that chair is a scooter with steering done by a servo. No mixing, no tank steer. So use one of those special controllers to have servo steering.