Direct-drive sim racing wheel


A direct-drive simulator steering wheelbase is a simulator steering wheel with a direct-drive mechanism between the drive and output, i.e. without gearing, and is used similarly as with other simulator steering wheels for providing torque feedback so that the driver, through movement in the steering wheel, gets an interface for sensing what is happening to the car in the simulator. It is an example of human–computer interaction in driving simulators, racing simulators, and racing video games, and is an example of haptic technology.
Direct-drive steering wheels typically differ from geared or belted sim racing wheels by being stronger, and being able to more accurately reproduce details from the simulator. They are typically constructed using a 3-phase brushless AC servomotor, or sometimes a hybrid stepper-servomotor, or only a stepper motor.
In a direct drive simracing steering wheel system, the wheelbase and the wheel rim are typically separate, so that is possible to switch between rims according to the use case, for instance formula wheelrims, GT wheelrims, oval racing or truck wheel rims. The base and the rim are typically connected through a quick release system.

History

s for use in industrial arms began to be possible in the 1980s, with the use of rare-earth magnets, of which today the most commonly used are neodymium magnets.
Before the 1980s, servo motors were not powerful enough to be used directly, and therefore reduction gears or mechanical belts were added to the motor to leverage and multiply its power. Higher-power motors were not feasible due to the expensive rare-earth materials needed to build them. This problem was surpassed in the 1980s, with the development of less-expensive high-power magnets.
In 2013, direct-drive sim steering wheels were introduced in large scale to the consumer mass market as a more advanced alternative to gear- and belt-driven steering wheels. The first commercially broadly available direct-drive wheel base was released in 2013 by the UK-based , after having been retailing to racing teams and professional centers since 2008. It was followed in 2015 by the US-based SimXperience AccuForce V1, and by the first do-it-yourself open-source hardware OpenSimwheel or "OSW" kits for users with good technical knowledge.
In 2015, a preliminary comparison of gear-driven and direct-drive wheels in the 0–30 Hz frequency range, for a study on hard real-time multibody simulation and high-fidelity steering wheel force feedback, concluded that direct-drive wheels are preferable.
Simucube was one of the manufacturers who previously provided Open Sim Wheel kits, and is a brand name owned by the Finnish manufacturer Granite Devices, which also supplies driver electronics for controlling servomotors and stepper motors, both for sim racing and industrial use. Granite Devices started as a hobby project by the Finn Kontkanen Tero when he was building a CNC milling machine, and realised that there was many alternating current servomotors of high quality on the market, but that driver electronics for controlling such motors was expensive or hard to come by. He investigated the operation of AC servos, and realized that it was possible to make usable control electronics with a handful of the latest electronic components and some real-time algorithms. The development of the controller then took around a year. The electronics are based on an IONI motherboard and STM32F4, and a proprietary firmware called MMos. An open source version of this software has been planned for release, but has not yet been released as of 2022.

Performance metrics

Issues, quality, and performance indicators of direct-drive wheels, and of sim racing wheels in general, include detail and fidelity of force feedback, smooth torque transmission, nearly-zero backlash, rotary encoder resolution, clipping, dynamic range, torque ripple, cogging torque, drivers and digital signal processing with control electronics, signal filtering, backdrive friction, low inertia, damping, fast response, precise positioning, electromagnetic interference, and latency.

Construction

Motors

The Leo Bodnar, OSW kits, Sim-pli.city and VRS systems are based on industrial servo motors, while SimXperience's AccuForce, Frex, Simucube, Fanatec, and Simagic use custom-made motors. The types of motors used vary between high-end 3-phase brushless servomotors and lower budget hybrid stepper-servo motors. In-runner servo motors are typically smoother and more expensive than stepper or outrunner motors. Outrunner motors typically can produce more torque than inrunner motors, but need more cooling at higher torque levels.

Control electronics

Other than the motor, other parts of a complete direct-drive wheelbase include a rotary encoder, a controller board, and a motor driver board, which fits into a slot of the controller board, and that controls the position, velocity and torque output of the motor. Examples of encoders are the Biss-C and the SinCos encoders, an example of a controller board is the Simucube board, and some examples of motor driver boards are the IONI and the Argon ones.
The motor encoder reads the position and/or motion of the shaft. The resolution of the encoder is typically measured in PPR, but sometimes CPR is used instead, where 1 pulse equals 4 counts. The main advantage of very high resolution encoders is the ability to implement more advanced firmware or software FFB filters to the force feedback signal; for instance, encoders with a 21-bit resolution or more, like the SinCos encoder, allow the servo-motor electronics to handle the filters more smoothly, and also allow to have more nuances in the FFB signal.
One of the main purposes of FFB filters is to optimize the FFB signal for a given wheelbase and rim device. The most basic FFB filters include the reconstruction filter, damper, friction and inertia. The reconstruction filter is included even in non-directdrive wheelbases, and has the effect of interpolating and smoothing the FFB signal from the game, to reduce the noise and artifacts from the FFB signal caused by the low update rate of a racing game. The wheel rim weight and size also have a significant effect on the perceived FFB signal, with lighter and smaller wheels being able to move faster and deliver more details.
More advanced FFB filters include static force reduction and slew rate reduction filter. The static force reduction filter was introduced to address a problem that emerged with high-torque DD wheelbase, due to their force output making too difficult to even turn the wheel with some cars in high-speed corners. The static force reduction filter introduced with Simucube 2 wheelbase allowed to address this issue while keeping a fully linear signal. A side-effect of this filter however is that while turning the wheel one feels a weakening of the FFB signal, which some drivers might dislike. Similarly, the slew rate reduction filter reduces or dampens sudden acceleration spikes in FFB torque, due for example to hitting kerbs or bumps. Therefore, the static force reduction and slew rate reduction filters make feasible to drive with higher maximum torque settings, which can enhance micro-details in the FFB signal.

Torque

The torque says something about how "powerful" the engine is, and can be specified in two ways:
  • Continuous torque, the greatest load of which the motor still can perform continuous movement at a continuous speed, and thus performing continuous work
  • Stall torque, the load which will cause the motor to stop so that it can no longer move, and thus produces a holding torque, but not performing any work
The latter always gives a higher number in newton-meters, and is therefore the number that usually is communicated the most by manufacturers to consumers, but is actually a less useful specification since the steering wheel in theory does not perform any work when rotation has stopped. One must therefore be aware of the type of torque specification given when comparing two motors. The relationship between the continuous torque and stall torque can vary between motors, and can say something about the motor characteristics.
For comparison, usually around 7-10 Nm is experienced in a street car, and on steering wheels with very high torque it may therefore be appropriate to adjust the torque down in the software. However, the stronger motors will often have a faster slew rate which gives better steering response and more realism.

Steering wheel mount

Similar to many real-world racing cars, sim-racing steering wheels usually come with a bolt circle of 6×70 mm, which means the wheel is mounted to the base via 6 evenly spaced out screws along a 70 mm circle on the steering wheel. Other bolt circles are sometimes used.
Some steering wheels attach to the base via quick release, as is commonly seen on many real-world racing cars, and these come in many varieties: Proprietary quick releases, or standardized quick releases such as the D1 spec. D1 spec couplers are built to the same pattern as the NRG quick coupler approved for use in real-world racing cars per SFI Spec 42.1. Formerly, another common aftermarket quick release has been the Q1R type. Some quick releases have integrated contact pins for transferring power and data to buttons and displays on the wheel, but these usually do not work across manufacturers. Others instead use wireless transmission via Bluetooth and inductive power transfer via the quick release. If using a steering wheel and base from two different manufacturers, it is usually possible to connect the steering wheel electronics to the base via a separate USB cable, for example connecting between USB-C, Micro, Mini, or Type B interfaces on the base and wheel.

Base mount

On bases with a high torque, the most robust mounting is usually achieved using an industry-standard front-mounted flange mount, and this is often preferred among sim racers, as such base mounts usually are less inclined to bend during heavy steering movements. This typically gives a shorter lever and therefore more sturdy mounting due to less torque on the mounting interface. A de facto industry standard among sim wheels, which again stems from a widely used mechanical industry standard, is a front mount with a bolt circle measuring 4×130 mm diameter and metric M8 screws, which means that four screws are evenly placed along a circle measuring 130 mm in diameter. This roughly corresponds to a square of 91.9 mm × 91.9 mm, which is often quoted as a square pattern with 92 mm long sides.
There are also a number of other proprietary patterns for mounting the base to a sim racing cockpit or table. Some of these instead have mounting on the sides or underside of the base.

List of direct-drive bases

Main specifications

Sorted chronologically by time of introduction:
ModelIntroducedPeak torque Slew rate Encoder ResolutionMotor
LeoBodnar Sim Steering201316 Nm12-bit EJ encoderKollmorgen AKM52G-ANCNEJ00, brushless servomotor, ⌀ 24.2 mm shaft
LeoBodnar Sim Steering 2 201516 Nm24-bit C resolver Kollmorgen AKM52G-ANCNC-00, brushless servomotor, ⌀ 24.2 mm shaft
LeoBodnar Sim Steering 2 201520.524-bit 16.7M cpr C resolver Kollmorgen AKM53G, brushless servomotor, ⌀ 24.2 mm shaft
"OSW" DIY kit, Lenze201529 Nm16k pprLenze MCS12H15L
"OSW" DIY kit, M15201530 Nm10k pprMiGE 130ST-M15015, ⌀ 22 mm shaft
"OSW" DIY kit, M10201520 Nm10k pprMiGE 130ST-M10010, ⌀ 22 mm shaft
"OSW" DIY kit, Hobbystar201520 Nm10k pprMiGE 130ST-M10010, ⌀ 22 mm shaft
Reimer Motorsports OpenSimwheel Premium201529 Nm16k cprLenze MCS12H15L
Reimer Motorsports OpenSimwheel Premium AKM52201524 Nm32k cprKollmorgen AKM52 3-phase AC servo, ⌀ 24.2 mm shaft
SimXperience AccuForce V1201516 Nm16k PPR encoderStepper motor, ⌀ 14 mm shaft
Frex SimWheel DD201616 NmMiGE servomotor
Sim-pli.city SW20201720 Nm10k ppr encoderMiGE 130ST-M10010, inrunner, ⌀ 22 mm shaft
SimXperience AccuForce V2201715.6 Nm16k resolutionHybrid stepper/servomotor, ⌀ 14 mm shaft
Simucube-based pre-assembled OSW kit 30 Nm5k or 10k ppr encoderMiGE 130ST-M15015, inrunner, ⌀ 22 mm shaft
Simucube-based pre-assembled OSW kit 20 Nm5k or 10k ppr encoderMiGE 130ST-M10010, inrunner, ⌀ 22 mm shaft
Simucube-based pre-assembled OSW kit Biss-C, M15201830 Nm22-bit in the 2018 versionMiGE 130ST-M15015, inrunner, ⌀ 22 mm shaft
Simucube-based pre-assembled OSW kit Biss-C, M10201820 Nm22-bit in the 2018 versionMiGE 130ST-M10010 or MiGE 130ST-M15015, inrunner, ⌀ 22 mm shaft
simracingbay "OSW" DIY kit201820 Nm22-bit MiGE 130ST-M10010, ⌀ 22 mm shaft
Augury Simulations SimuCube OSW Kit201818 NmMiGE servomotor, ⌀ 22 mm shaft
Sim-pli.city SW7C20187.1 NmMige 80ST Series Motor, inrunner, ⌀ 21.5 mm shaft
Sim-pli.city SW20 V3201920 Nm23-bit MiGE 130ST-M10010, inrunner, ⌀ 22 mm shaft
Simucube 2 Sport2019-04-0317 Nm4.822-bit absolute ultra low torque ripple Brushless Servomotor, inrunner
Simucube 2 Pro2019-04-0325 Nm8.022-bit absolute ultra low torque ripple Brushless Servomotor, inrunner
Simucube 2 Ultimate2019-04-0332 Nm9.524-bit absolute 24-bit, 16M cprultra low torque ripple Brushless Servomotor, inrunner
Fanatec Podium DD2201925 Nm16-bit Custom-made outrunner servomotor, hollow ⌀ shaft with USB-C for data and power
Fanatec Podium DD1201920 Nm16-bit Custom-made outrunner servomotor, hollow ⌀ shaft with USB-C for data and power
Fanatec Clubsport DD2023
Fanatec Clubsport DD+2023
Simagic Dynamic M102020-0110 NmServo-Stepper Motor
Sim-pli.city SW8C+20208 Nm23-bit MiGE 110ST-M06030, inrunner
VRS DirectForce Pro202020 Nm22-bit, absolute Biss encoderMiGE 130ST-M10010, inrunner, ⌀ 22 mm shaft
Simagic Alpha2020-12-0515 Nm18-bit based on hall sensor5-pole, 3-phase servomotor
Simagic Alpha-U 2021-10-1323 Nm18-bit5-pole servomotor
CAMMUS DDWB 20212021-1115servomotor
Fanatec CSL DD 2021-04-218 NmBrushless inrunner servomotor, hollow ⌀ shaft with USB-C for data and power
Fanatec CSL DD 2021-04-215 NmBrushless inrunner servomotor, hollow ⌀ shaft with USB-C for data and power
Simagic Alpha Mini2021-06-2713 Nm256k ppr, 40Khz response rate3-phase servomotor optimized for sim racing use, outrunner
Moza R212021-06-2321 Nm18-bits Servomotor, slanted-pole design
Moza R162021-06-2316 Nm18-bits Servomotor, slanted-pole design
IMMSource ET52022-02-1217 Nm 18-bit encoder Servomotor
IMMSource ET32022-02-1210 Nm18-bit encoder Servomotor
Moza R122023-06-2612 Nm15-bit 16-pole Servomotor, slanted-pole design
Moza R92022-03-109 Nm15-bit Outrunner servomotor
Moza R52022-08-305.5 Nm15-bit Outrunner servomotor
Moza R3 for Xbox2024-07-043.9 Nm15-bit encoderServomotor
Logitech G PRO Racing Wheel2022-09-2111 NmOutrunner servomotor
Asetek Invicta2022-11-1027 Nm9.422-bit absolute MiGE servomotor
Asetek Forte2022-11-1018 Nm6.722-bit MiGE servomotor
Asetek La Prima2022-11-1012 Nm4.022-bit MiGE servomotor
Thrustmaster T8182022-11-1710 Nm
CAMMUS C52023-06-097 Nm Servomotor
CAMMUS C122024-0212 NmServomotor
VNM Direct Drive Xtreme2024-033223-bit, absolute5-pole servomotor
Thrustmaster T5982024-10-19Direct Axial Drive
VRS DFP152024-1215 Nm21-bit, 10 kHz response rate5-Pole Servomotor
VNM Direct Drive Supreme2025-01-182523-bit, absolute5-pole servomotor
VNM Direct Drive Elite2025-01-181823-bit, absolute5-pole servomotor
VNM Direct Drive Premier2025-01-181323-bit, absolute5-pole servomotor
Simagic Alpha EVO Sport2025-04-28921-bit
Simagic Alpha EVO2025-04-281221-bit
Simagic Alpha EVO Pro2025-04-281821-bit
ModelIntroducedStall torqueSlew rate ResolutionMotor

Mount options and quick release

ModelIntroducedWheel bolt circleWheel quick releaseFront base mountOther base mountsOther notes
LeoBodnar Sim Steering20136×70 mmNot included4×140 mm bolt circle
No3000 r/min
LeoBodnar Sim Steering 2 20156×70 mmNot included4×140 mm bolt circle
No3000 r/min, rated speed 5600 r/min, rotor inertia 4.58 kg-cm2
LeoBodnar Sim Steering 2 20156×70 mmNot included4×140 mm bolt circle
NoRated speed 5100 r/min, rotor inertia 6.64 kg-cm2
"OSW" DIY kit, Lenze20156×70 mmNot included4×130 mm bolt circle
No1500 r/min, rotor inertia: 7.3 kg cm2
"OSW" DIY kit, M1520156×70 mmNot included4×130 mm bolt circle
No1500 r/min, rotor inertia: 27.7 kg cm2
"OSW" DIY kit, M1020156×70 mmQ1R 4×130 mm bolt circle
No1000 r/min, rotor inertia: 19.4 kg cm2
"OSW" DIY kit, Hobbystar20156×70 mmQ1R 4×130 mm bolt circle
No1000 r/min, rotor inertia: 19.4 kg cm2
Reimer Motorsports OpenSimwheel Premium20156×70 mmNot included4×130 mm bolt circle
NoGranite Devices Argon electronics
Reimer Motorsports OpenSimwheel Premium AKM5220156×70 mmNot included4×130 mm bolt circle
NoGranite Devices Argon electronics
SimXperience AccuForce V120156×70 mmD1 specNoUnder, rectangle:
▭ 79.4 mm × 135 mm
Frex SimWheel DD20163×50.8 mmFrex quick release4×130 mm bolt circle
NoMini USB
Sim-pli.city SW2020176×70 mmNot included4×130 mm bolt circle
NoController: Granite Devices IONI Pro and SimuCUBE; 1000 r/min; rotor inertia 19.4 kg cm2
SimXperience AccuForce V220176×70 mmD1 specNoUnder, rectangle:
▭ 39.4 mm × 135 mm
Simucube-based pre-assembled OSW kit 6×70 mmNot included4×130 mm bolt circle
NoIONI Pro HC controller, SimuCUBE motherboard; 1500 r/min ; 27.7 kg cm2
Simucube-based pre-assembled OSW kit 6×70 mmNot included4×130 mm bolt circle
NoIONI Pro controller, SimuCUBE motherboard; 1000 r/min ; rotor inertia: 19.4 kg cm2
Simucube-based pre-assembled OSW kit Biss-C, M1520186×70 mmNot included4×130 mm bolt circle
NoBiss-C encoder; 1500 r/min, 27.7 kg cm2 rotor inertia
Simucube-based pre-assembled OSW kit Biss-C, M1020186×70 mmNot included4×130 mm bolt circle
NoBiss-C encoder; 1000 r/min, 19.4 kg cm2 rotor inertia
simracingbay "OSW" DIY kit20186×70 mmNot included4×130 mm bolt circle
NoSinCos encoder; driver board: Granite Devices IONI servo drive, IoniProHC 25A; 1000 r/min, 19.4 kg cm2 rotor inertia
Augury Simulations SimuCube OSW Kit20186×70 mmQuick release directly on axle 4×130 mm bolt circle
No
Sim-pli.city SW7C20186×70 mmNot included4×130 mm bolt circle
No
Sim-pli.city SW20 V320196×70 mmNot included4×130 mm bolt circle
No1000 r/min, 19.4 kg cm2 rotor inertia
Simucube 2 Pro20196×70 mmSimucube SQR hub4×145 mm bolt circle
No
Simucube 2 Sport20196×70 mmSimucube SQR hub4×145 mm bolt circle
No
Fanatec Podium DD22019Requires adapterFanatec QR1 quick releaseNoUnder, triangle:
▽ 78.4 mm, 66 mm

Side: ◦ Two screw holes on each side
12-bit MHL200 rotary position hall encoder
Fanatec Podium DD12019Requires adapterFanatec QR1 quick releaseNoUnder, triangle:
▽ 78.4 mm, 66 mm

Side: ◦ Two screw holes on each side
12-bit MHL200 rotaty position hall encoder
Fanatec Clubsport DD2023Fanatec QR2 quick release
Fanatec Clubsport DD+2023Fanatec QR2 quick release
Simagic Dynamic M102020-016×70 mmD1 specNoSide, rectangle: ▭ Via slots for T-nuts LME2500FE encoder
Sim-pli.city SW8C+20206×70 mmNot included4×130 mm bolt circle
No
VRS DirectForce Pro20206×70 mmNot included4×130 mm bolt circle
No1000 r/min; rotor inertia 19.4 kg cm2
Simagic Alpha2020-12-056×70 mmD1 spec4×130 mm bolt circle
No
Fanatec CSL DD 2021-04-21Requires adapterFanatec QR1 quick releaseNoUnder: ▭ 3 T-slots, 40 mm and 80 mm c-c

Side: ▭ 2 T-slots, 70 mm c-c
Flux Barrier Rotor, hall-position-sensor
Fanatec CSL DD 2021-04-21Requires adapterFanatec QR1 quick releaseNoUnder: ▭ 3 T-slots, 40 mm and 80 mm c-c

Side: ▭ 2 T-slots, 70 mm c-c
Flux Barrier Rotor, hall-position-sensor
Simagic Alpha Mini2021-06-276×70 mmD1 spec4×130 mm bolt circle
Side, two holes: ─

Under, rectangle: ▯ 67 mm × 80 mm
Moza R212021-06-236×70 mmD1 specNoUnder, rectangle:
▯ 78.5 mm × 66 mm
480 W, 262 144 ppr resolution, 1000 Hz USB, wireless wheel
Moza R162021-06-236×70 mmD1 specNoUnder, rectangle:
▯ 78.5 mm × 66 mm
360 W, 262 144 ppr resolution, 1000 Hz USB, wireless wheel
IMMSource ET52022-02-126×70 mmD1 spec4×130 mm bolt circle
No
IMMSource ET32022-02-126×70 mmD1 spec4×130 mm bolt circle
NoWireless wheel, with USB-C as an alternative
Moza R122023-06-266×70 mmD1 spec4×70 mm bolt circle Under, rectangle:
▯ 78.5 mm × 66 mm
216 W, 1000 Hz USB, wireless wheel
Moza R92022-03-106×70 mmD1 specNoUnder, rectangle:
▯ 78.5 mm × 66 mm
180 W power supply, wireless wheel
Moza R52022-08-306×70 mmD1 specNoUnder, rectangle:
▯ 78.4 mm × 40 mm
Wireless wheel, with USB-C as an alternative
Moza R3 for Xbox2024-07-046×70 mmD1 spec4×60 mm bolt circle Under, rectangle:
▯ 78.5 mm × 66 mm
72 W, 1000 Hz USB, wireless wheel
Logitech G PRO Racing Wheel2022-09-216×44.5 mm Logitech quick releaseNoTable clampSeparate models with support for either Xbox or PlayStation. The paddles can be used for gear shifting or for throttle/braking. Separate paddles for dual clutch operation.
Asetek Invicta2022-11-10missing dataAsetek quick release Front: Proprietary Under: ▭ 2 T-slots, 87 mm c-c Power and USB to the steering wheel through the quick release, via a hollow drive shaft and a slip ring. Integrated measurement of the motors torque output. Initial models only for PC via USB-C. USB-C hub with 5 ports for extra peripherals. Integrated control electronics. External power supply via Molex connector.
Asetek Forte2022-11-10missing dataAsetek quick release Front: Proprietary Under: ▭ 2 T-slots, 87 mm c-c Power and USB to the steering wheel through the quick release, via a hollow drive shaft and a slip ring. Integrated measurement of the motors torque output. Initial models only for PC via USB-C. USB-C hub with 5 ports for extra peripherals. Integrated control electronics. External power supply via Molex connector.
Asetek La Prima2022-11-10missing dataAsetek quick release Front: Proprietary Under: ▭ 2 T-slots, 87 mm c-c Asetek's entry-level model. Power and USB to the steering wheel through the quick release, via a hollow drive shaft and a slip ring. Integrated measurement of the motors torque output. Initial models only for PC via USB-C. Only one USB-C connection directly to PC. Integrated control electronics. External power supply via Molex connector.
Thrustmaster T8182022-11-17NoNew proprietary Thrustmaster quick releaseNoUnder: ▭ 4 screw holes, spaced 79 mm c-c lengthwise, 63 mm c-c widthwise 168 W power supply, RJ-45 and USB-C interface in the base, proprietary 3-pin contact for electric signals via wheel connector.
CAMMUS C52023-06-09NoNoNoFirst direct drive wheel top integrate motor and wheel integrated together
CAMMUS C122024-026×70 mmNoUses C5 Technology
ModelIntroducedWheel bolt circleWheel quick releaseFront base mountOther base mountsOther notes

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