> For the complete documentation index, see [llms.txt](https://carec.gitbook.io/carec-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://carec.gitbook.io/carec-docs/documentation/simulation/wheelchair-model.md).

# Wheelchair Model

The first model represents a configurable powered-wheelchair platform, not a claim about a finalized product. It must support manual, assisted, and autonomous software paths through the same drive and safety interfaces.

## Parameter register

| Group             | Parameters                                                                   | Evidence source                                  |
| ----------------- | ---------------------------------------------------------------------------- | ------------------------------------------------ |
| Geometry          | Overall length/width/height, wheelbase, track, wheel radius, caster position | Measurement or CAD                               |
| Occupied envelope | Footrest, user envelope, accessories, sensor mast                            | Conservative design assumption, then measurement |
| Mass properties   | Total mass, center of mass, link inertia                                     | CAD/scale tests/system identification            |
| Drive             | Velocity, acceleration, deceleration, jerk, deadband, saturation             | Manufacturer data and controlled test            |
| Contact           | Friction, rolling resistance, slip, caster behavior                          | Calibrated experiment                            |
| Timing            | Command latency, controller rate, watchdog, brake response                   | Logged bench test                                |
| Sensors           | Pose, field of view, range, rate, noise, latency                             | Datasheet and calibration                        |

Each value is tagged `measured`, `manufacturer`, `estimated`, or `provisional`, with units, date, owner, source link, uncertainty, and applicable hardware revision.

## Collision and dynamics rules

* Prefer simple collision primitives or low-poly meshes.
* Keep collision geometry conservative around the occupied envelope.
* Do not use visual meshes as collision meshes without checking complexity and shape.
* Use physically valid inertia tensors and realistic masses.
* Model saturation, acceleration limits, command delay, and timeout in the drive path.
* Add caster/contact detail only when it changes the test outcome.

## Calibration tests

Run straight-line distance, in-place rotation, constant-radius turn, coast/stop, low-speed command, threshold crossing, slope hold, and wheel-slip tests. Compare simulated and measured traces using declared tolerances.


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