Swerve drive alternatives...

[Don Y]

The electric wheelchair I\'ve automated has \"issues\" with changes
in direction. These are a result of the way the non-powered wheels
are connected to the frame.

<https://www.permobil.com/en-us/products/power-wheelchairs/permobil-m300-corpus-hd>

If you examine the front and rear pairs of wheels, you can see that
the point of contact with the floor (which is last to change during
a turn) is not directly below the pivot point where the wheel
assembly connects to the frame.

[This is a \"mid-wheel\" drive chair; the two middle wheels provide
the motorization and the other four are just along for the ride]

So, when attempting turns, the chair doesn\'t \"turn on a dime\"
(as it would if only the middle wheels were involved); the front
(rear) jog out to the side as the turn is executed. This makes it
tedious to control the motion in confined spaces.

A swerve drive would be ideal -- but incredible overkill (and
overco$t!)

It seems like the easiest fix would be to replace the front and
rear pairs of wheels with casters that can pivot on their mounting
axis? Control algorithms could then assume the chair could spin on
a dime which makes navigating down hallways (e.g.) considerably
easier (move to point adjacent doorway; spin; enter doorway)

[Of course, you still have to monitor the total circumscribed volume
to ensure the \"spin\" won\'t damage the surroundings... but, that is a
constant, much easier to manage]

 

[John Larkin]

On Mon, 21 Aug 2023 03:25:34 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

The electric wheelchair I\'ve automated has \"issues\" with changes
in direction. These are a result of the way the non-powered wheels
are connected to the frame.

https://www.permobil.com/en-us/products/power-wheelchairs/permobil-m300-corpus-hd

If you examine the front and rear pairs of wheels, you can see that
the point of contact with the floor (which is last to change during
a turn) is not directly below the pivot point where the wheel
assembly connects to the frame.

[This is a \"mid-wheel\" drive chair; the two middle wheels provide
the motorization and the other four are just along for the ride]

So, when attempting turns, the chair doesn\'t \"turn on a dime\"
(as it would if only the middle wheels were involved); the front
(rear) jog out to the side as the turn is executed. This makes it
tedious to control the motion in confined spaces.

A swerve drive would be ideal -- but incredible overkill (and
overco$t!)

It seems like the easiest fix would be to replace the front and
rear pairs of wheels with casters that can pivot on their mounting
axis? Control algorithms could then assume the chair could spin on
a dime which makes navigating down hallways (e.g.) considerably
easier (move to point adjacent doorway; spin; enter doorway)

[Of course, you still have to monitor the total circumscribed volume
to ensure the \"spin\" won\'t damage the surroundings... but, that is a
constant, much easier to manage]

Wheelchairs are generally klunky. Someone should design a sleek,
sporty, glamorous, high-performance one, with good lights and sound
system and some good color options.

 

[Eddy Lee]

On Monday, August 21, 2023 at 3:49:02 AM UTC-7, John Larkin wrote:

On Mon, 21 Aug 2023 03:25:34 -0700, Don Y
blocked...@foo.invalid> wrote:

The electric wheelchair I\'ve automated has \"issues\" with changes
in direction. These are a result of the way the non-powered wheels
are connected to the frame.

https://www.permobil.com/en-us/products/power-wheelchairs/permobil-m300-corpus-hd

If you examine the front and rear pairs of wheels, you can see that
the point of contact with the floor (which is last to change during
a turn) is not directly below the pivot point where the wheel
assembly connects to the frame.

[This is a \"mid-wheel\" drive chair; the two middle wheels provide
the motorization and the other four are just along for the ride]

So, when attempting turns, the chair doesn\'t \"turn on a dime\"
(as it would if only the middle wheels were involved); the front
(rear) jog out to the side as the turn is executed. This makes it
tedious to control the motion in confined spaces.

A swerve drive would be ideal -- but incredible overkill (and
overco$t!)

It seems like the easiest fix would be to replace the front and
rear pairs of wheels with casters that can pivot on their mounting
axis? Control algorithms could then assume the chair could spin on
a dime which makes navigating down hallways (e.g.) considerably
easier (move to point adjacent doorway; spin; enter doorway)

[Of course, you still have to monitor the total circumscribed volume
to ensure the \"spin\" won\'t damage the surroundings... but, that is a
constant, much easier to manage]
Wheelchairs are generally klunky. Someone should design a sleek,
sporty, glamorous, high-performance one, with good lights and sound
system and some good color options.

And self driving hard/soft-ware. Or at least remote controlled.

 

[John Larkin]

On Mon, 21 Aug 2023 07:33:13 -0700 (PDT), Eddy Lee
<eddy711lee@gmail.com> wrote:

On Monday, August 21, 2023 at 3:49:02?AM UTC-7, John Larkin wrote:
On Mon, 21 Aug 2023 03:25:34 -0700, Don Y
blocked...@foo.invalid> wrote:

The electric wheelchair I\'ve automated has \"issues\" with changes
in direction. These are a result of the way the non-powered wheels
are connected to the frame.

https://www.permobil.com/en-us/products/power-wheelchairs/permobil-m300-corpus-hd

If you examine the front and rear pairs of wheels, you can see that
the point of contact with the floor (which is last to change during
a turn) is not directly below the pivot point where the wheel
assembly connects to the frame.

[This is a \"mid-wheel\" drive chair; the two middle wheels provide
the motorization and the other four are just along for the ride]

So, when attempting turns, the chair doesn\'t \"turn on a dime\"
(as it would if only the middle wheels were involved); the front
(rear) jog out to the side as the turn is executed. This makes it
tedious to control the motion in confined spaces.

A swerve drive would be ideal -- but incredible overkill (and
overco$t!)

It seems like the easiest fix would be to replace the front and
rear pairs of wheels with casters that can pivot on their mounting
axis? Control algorithms could then assume the chair could spin on
a dime which makes navigating down hallways (e.g.) considerably
easier (move to point adjacent doorway; spin; enter doorway)

[Of course, you still have to monitor the total circumscribed volume
to ensure the \"spin\" won\'t damage the surroundings... but, that is a
constant, much easier to manage]
Wheelchairs are generally klunky. Someone should design a sleek,
sporty, glamorous, high-performance one, with good lights and sound
system and some good color options.

And self driving hard/soft-ware. Or at least remote controlled.

People have various handicaps so the controls would have to be very
versatile. Pre-programmed routes, or Autopilot type things maybe.

I\'d expect one could round up a lot of vounteers (and money) to work
on the project.

 

[Don Y]

On 8/21/2023 7:33 AM, Eddy Lee wrote:
> And self driving hard/soft-ware. Or at least remote controlled.

(Long distance) Remote-controlled has been done, before.
\"Nearby\" remote control is a standard option on most chairs
(so a care provider can steer the chair without having
to bend over the occupant)

I\'ve made a first pass at \"self-driving\" that is demonstrably viable.
I can let someone climb out of their chair, at bedside -- and then send
the chair \"off\" to park itself out-of-the-way... to be recalled, later,
when its occupant wants to again climb on board.

But, in the confines of pre-ADA home, the spaces to navigate are too
confining. Unless you can monitor EVERY mechanical aspect of the
chair, changes in direction can cause the chair to jog \"the wrong
way\" before coming about to the intended direction.

My algorithms are smart enough to notice if you\'ve got the chair
partially reclined, seat tilted, legs elevated, etc. and know
the revised dimensions of the enclosing envelope (i.e., a fully
reclined chair with legs lifted and *occupied* is ~6+ ft long;
seated upright, legs tucked under reduces that to a couple of feet).
So, a more appropriate path (FROM,TO) can be chosen. Or, barring
the availability of such a path, the occupant can be asked if
he\'d like his \"chair attitude\" to be adjusted to better fit the
available path(s).

If you\'re already dealing with narrow halls and doorways, a couple
of inches \"the wrong way\" leaves \"lasting impressions\" on the walls
and wood trim! :> (I demo the software in the driveway with
office partitions to simulate the walls in the arena as I have no
desire to incur the ire of SWMBO for my \"playthings\"!)

 

[Don Y]

On 8/21/2023 8:41 AM, Don Y wrote:

On 8/21/2023 7:33 AM, Eddy Lee wrote:
And self driving hard/soft-ware.  Or at least remote controlled.

(Long distance) Remote-controlled has been done, before.
\"Nearby\" remote control is a standard option on most chairs
(so a care provider can steer the chair without having
to bend over the occupant)

<https://www.permobil.com/en-us/products/accessories/drive-controls/standard-attendant-control>

Note that the care giver is expected to be nearby the chair.

This is a commercially available chair with wireless remote:

<https://www.amazon.com/2021-Foldable-Electric-Wheelchair-Wheelchairs/dp/B08R6JWRD3>

The controls are easy to interface to -- even R-Net. The real
issue is situational awareness on the part of the \"operator\".

 

[John Larkin]

On Mon, 21 Aug 2023 08:41:14 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

On 8/21/2023 7:33 AM, Eddy Lee wrote:
And self driving hard/soft-ware. Or at least remote controlled.

(Long distance) Remote-controlled has been done, before.
\"Nearby\" remote control is a standard option on most chairs
(so a care provider can steer the chair without having
to bend over the occupant)

I\'ve made a first pass at \"self-driving\" that is demonstrably viable.
I can let someone climb out of their chair, at bedside -- and then send
the chair \"off\" to park itself out-of-the-way... to be recalled, later,
when its occupant wants to again climb on board.

But, in the confines of pre-ADA home, the spaces to navigate are too
confining. Unless you can monitor EVERY mechanical aspect of the
chair, changes in direction can cause the chair to jog \"the wrong
way\" before coming about to the intended direction.

It should have independent abilities to translate and rotate. Go into
the kitchen sideways if you want.

My algorithms are smart enough to notice if you\'ve got the chair
partially reclined, seat tilted, legs elevated, etc. and know
the revised dimensions of the enclosing envelope (i.e., a fully
reclined chair with legs lifted and *occupied* is ~6+ ft long;
seated upright, legs tucked under reduces that to a couple of feet).
So, a more appropriate path (FROM,TO) can be chosen. Or, barring
the availability of such a path, the occupant can be asked if
he\'d like his \"chair attitude\" to be adjusted to better fit the
available path(s).

If you\'re already dealing with narrow halls and doorways, a couple
of inches \"the wrong way\" leaves \"lasting impressions\" on the walls
and wood trim! :> (I demo the software in the driveway with
office partitions to simulate the walls in the arena as I have no
desire to incur the ire of SWMBO for my \"playthings\"!)

 

[John Larkin]

On Mon, 21 Aug 2023 08:59:52 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

On 8/21/2023 8:41 AM, Don Y wrote:
On 8/21/2023 7:33 AM, Eddy Lee wrote:
And self driving hard/soft-ware.  Or at least remote controlled.

(Long distance) Remote-controlled has been done, before.
\"Nearby\" remote control is a standard option on most chairs
(so a care provider can steer the chair without having
to bend over the occupant)

https://www.permobil.com/en-us/products/accessories/drive-controls/standard-attendant-control

Note that the care giver is expected to be nearby the chair.

This is a commercially available chair with wireless remote:

https://www.amazon.com/2021-Foldable-Electric-Wheelchair-Wheelchairs/dp/B08R6JWRD3

The controls are easy to interface to -- even R-Net. The real
issue is situational awareness on the part of the \"operator\".

It LOOKS handicapped! Hardly sporty.

 

[Lasse Langwadt Christensen]

mandag den 21. august 2023 kl. 18.11.52 UTC+2 skrev John Larkin:

On Mon, 21 Aug 2023 08:41:14 -0700, Don Y
blocked...@foo.invalid> wrote:

On 8/21/2023 7:33 AM, Eddy Lee wrote:
And self driving hard/soft-ware. Or at least remote controlled.

(Long distance) Remote-controlled has been done, before.
\"Nearby\" remote control is a standard option on most chairs
(so a care provider can steer the chair without having
to bend over the occupant)

I\'ve made a first pass at \"self-driving\" that is demonstrably viable.
I can let someone climb out of their chair, at bedside -- and then send
the chair \"off\" to park itself out-of-the-way... to be recalled, later,
when its occupant wants to again climb on board.

But, in the confines of pre-ADA home, the spaces to navigate are too
confining. Unless you can monitor EVERY mechanical aspect of the
chair, changes in direction can cause the chair to jog \"the wrong
way\" before coming about to the intended direction.
It should have independent abilities to translate and rotate. Go into
the kitchen sideways if you want.

omni wheels https://youtu.be/ZjmvFvVAJTo

 

[Don Y]

On 8/21/2023 10:09 AM, Lasse Langwadt Christensen wrote:
> omni wheels https://youtu.be/ZjmvFvVAJTo

Most chairs have two drive wheels, directly opposite each other
(scooters have *one* drive motor).

As they can be driven in opposite directions, turning on a dime
is possible -- if not for the other wheels and the manner that
they connect to the chassis.

Of course, the size of the dime varies with front, mid and rear
drive based on the wheels\' placements relative to the overall
frame size and design.