📢 Important: This is a pre-release of the project and considered to be under active development and testing. If you're not prepared to do some tinkering and/or deal with initial usability issues, it is recommended that you do not attempt to build it right now and instead wait for the
v1.0release
A haptic device for sim racing, designed specifically for people who do not have a background in software or electronics.
It requires no soldering or programming and can be built for as little as ~215 GBP including the harness.
An active belt tensioner is a device that attaches between your sim rig and the anchor points of your racing harness. It dynamically tensions the harness in response to game telemetry; giving a sense of the forces you'd be experencing in a vehicle when changing speed, braking, cornering and jumping/landing.
It works with any game fully supported by SimHub, but the current software is designed primarily for racing games and simulators.
This project consists of three parts:
- A shopping list of components, readily available from online sellers
- Printable parts and instructions on how to assemble them
- A SimHub plugin that controls the hardware and allows customisation of the effects
The printable files and software are completely free (except the required SimHub License). The printed part designs are CERN-OHL-P licensed (open-source), and the software is MIT licensed, which essentially means you can do what you like with either; including selling printed/machined parts kits.
- Lowest Practical Cost
- Minimal Parts & Tools
- No Soldering
- No Programming
- No 'Reclaimed' Parts
- Direct-Drive (FOC/BLDC) Performance & Flexibility
Anyone with a sim rig that desires a more immersive experience. It's a plug-and-play design that requires no soldering or programming, so virtually anyone can build it.
Note that you'll need either an aluminium profile (e.g. GT Omega Prime) or 2" tubular steel (e.g. GT Omega Titan) sim rig frame to mount this using the available brackets. Mounting to other types of rig is possible, but you'll need to design and fabricate your own brackets (or get in touch with me). We are currently testing bracket designs for the Playseat Challenge.
I would recommend installing tactile transducers (bass shakers) before embarking on belt tensioners and other more exotic haptic systems. Transducers are by far the simplest and cheapest way of adding real immersion to your experience. They provide detail that belt tensioners cannot (road bumps, curbs, etc), while tensioners provide constant forces that transducers cannot (braking, cornering, etc).
Several members of the sim racing community have provided photographs of their SABT builds. Many have also forked the project and customised it to their needs.
If you build a SABT, you're encouraged to photograph and document your completed installation. A good way to do that is by creating a new GitHub discussion.
If you have your own 3D printer, as little as 215 GBP including taxes and delivery. If not, 250~300 GBP depending on your choice of printed parts supplier.
| Price (GBP) | Part | Notes |
|---|---|---|
| 120 | 2 x Motors | Provides the tensioning force |
| 20 | Controller | Provides USB control of the motors |
| 6 | 2 x Bearings | Allows the pulley covers to rotate smoothly |
| 7 | Screw & Nut Set | Provides every needed fastener in one set (with many spares) |
| 5 | 1M Cord | A low-friction cord that winds around the pulleys (attached at the other end to your belts) |
| 20 | Power Supply | Provides DC power to the motors |
| 12 | Back Driving Protection Unit | Prevents power-supply resets if the motors are back-driven (optional but recommended) |
| 25 | 4/5/6-Point 2" Harness | A low-cost Aliexpress model or used/expired FIA harness |
| 215 | Total | ...excluding printables |
There is a detailed parts list with sources in the build guide.
| Price (GBP) | Method | Notes |
|---|---|---|
| 5~10 | Self-Print | Roughly 200g or 75M of filament |
| 30~60 | FDM Service | Assuming an eBay-tier printing provider, not a professional company |
| 60~90 | MJF/SLS Service | JLC3DP and 3DPrintUK used for reference pricing (nylon dyed black with peening) |
Note that you will also need SimHub Licensed Edition (currently 8 EUR or more) to use this device. If you're reading this, you almost certainly already have it.
The two motors are anchored to your rig with printed brackets. A self-orienting pulley is attached to the face of each motor.
The ends of each shoulder belt are attached to lengths UHMWPE/Dyneema cord, which are wrapped around each motor pulley.
When SimHub sends game telemetry to our plugin, it converts this into torque commands and send them to the motors over a serial connection.
Since we're using high-quality BLDC/FOC integrated servo motors, the effects are applied directly as force (torque) rather than emulated by moving the belts a fixed distance, as with some DIY tensioners based on RC servos.
The benefits of this are:
- Smooth and silent operation
- Compact & clean design
- Auto-adjusting of the harness (adjustable idle tension)
The maximum force appliable by these motors with the current pulley design is about 10Kgf per belt, putting us right around the rated mechanical loading for each motor. Imagine having ~10Kg of weights attached to each belt hanging down from the back of your seat, and you'll get the idea.
This is plenty to give extra immersion and feedback, but significantly less than you'd feel in a real vehicle at motorsport velocities.
For comparison, the QS-BT1 claims "20.5kg per channel", but is a considerably larger and costs six times more.
Note that this system conveys progressive constant forces (cornering, braking, etc) rather than fine details (road texture, track kerbs, etc). For the latter, you should install one or more tactile transducers. The two work together to imply the sensation of movement without a costly motion simulator.
Force.Testing.webm
There is considerable variation in rig, seat and harness designs, so I cannot anticipate every possible configuration. You'll need to decide if this system is suitable for your rig by looking at the installations examples and instructions.
Of particular note:
- The belt clamp designs are intended for 2" wide belts of up to 2MM thickness. If your belts are wider or thicker than this, you will need to modify the design (or let me know and I'll create additional designs)
- The need for belt rollers depends on the seat design. In many cases applying low-friction tape is sufficient. A 'universal' Belt Roller design is included should you wish to use it
- The system includes a design for a Back Driving Protection Unit, which prevents your power supply's protection circuitry from tripping when the motors are back-driven (e.g. by pulling fast on the belts). This is an optional component, but highly recommended. A zero-soldering solution is available, but even the soldered version is very simple to assemble
- Although the motors and driver board can tolerate up to
24Vsupply, I've found that15Vis a good compromise. Operating at the maximum24Vis not reccommended, because any voltage spikes risk damaging the motors. Common19Vlaptop power supplies have been tested and work; but the higher the voltage, the greater the risk of damage
This is an open-source project involving powerful motors, pinch points and moving belts attached to your body.
With that said, design measures have been taken with safety in mind. See SAFETY.md for details.
Read through the instructions to get a better idea of what's involved and how to proceed.
📢 Important: This is a pre-release of the project and considered to be under active development and testing. If you're not prepared to do some tinkering and/or deal with initial usability issues, it is recommended that you do not attempt to build it right now and instead wait for the
v1.0release