Steer-by-wire

Steer-by-wire, in the context of the automotive industry, is a technology or system that allows steering some or all of a vehicle's wheels without a steering column connected to the wheel axles. It is different from electric power steering or power-assist, as those systems still rely on the steering column to transfer some steering torque to the wheels.[3] It is often associated with other drive by wire technologies.

SpeedE, an academic concept car developed for studying drive-by-wire technologies[1][2]

A vehicle with a steer-by-wire system may be manually controlled by a driver through a steering wheel, a yoke, or any other steering apparatus which is connected to one or more electronic control units, which uses the input to control steering actuators that turn the wheels side-to-side, steering the vehicle. The steering wheel or yoke may be equipped with haptic feedback to simulate road feel and wheel resistance, and change depending on the vehicle speed or customizable settings.[3][4]

The safety of drive-by-wire systems is often ensured through redundancy, for example through redundant input sensors, redundant vehicle communication networks and power grids, redundant steering actuators per wheel, and fail-operational steering. If steering fails for one or even two wheels, the system can compensate with torque vectoring using the other available wheels.[5]

Concept vehicles and race cars

European Commissioner Günther Oettinger driving a Uniti car simulator with a simulated steer-by-wire system[6] and augmented reality HUD at CeBIT 2016

Several concept vehicles included steer-by-wire, such as ThyssenKrupp Presta Steering's Mercedes-Benz Unimog, General Motors' Hy-wire and Sequel, Saabs Prometheus and the Mazda Ryuga. Schaeffler Paravan Technologie has provided steer-by-wire systems for racing vehicles: a steer-by-wire Porsche Cayman GT4 raced the 2020 24 Hours of Nürburgring and finished 2nd place in its class and 29th overall; a steer-by-wire Mercedes-AMG GT3 raced the following year using the same system and finished 16th overall.[7][8]

Production vehicles

Coupled with traditional steering

Rear-axle-only steer-by-wire may be coupled with traditional front wheel steering for conditional four-wheel steering, reducing turning radius at low speeds and increasing stability at high speeds.[10] Purely mechanical four-wheel steering systems have been available in production cars since the 1980s, with computer-controlled electronically-actuated rear-axle steering becoming available shortly after. Car manufacturers that have offered rear-axle steering in the 2020s include Acura, Audi, Bentley, BMW, Cadillac, Ferrari, General Motors, Genesis, Lamborghini, Lexus, Mercedes-Benz, Porsche, and Rolls-Royce.[11]

One such rear-axle-only steer-by-wire system couple with traditional front steering was Quadrasteer. It was developed by Delphi and was offered starting 2002 on some General Motors trucks. Despite favorable reception the system was discontinued in 2005 due to poor market penetration of only 17 percent of sales of the same model, partially due to lack of familiarity with the system and partially due to its $1000 mark-up.[10]

Rolls-Royce vehicles based on the Architecture of Luxury platform, such as the Cullinan, Spectre, Ghost, and Phantom, have computer-controlled four-wheel steering.[12] The front wheel steering uses electric power assist[13] while an electronic system controls the rear wheel steering and turns them in the opposite direction of the front wheels when turning at lower speeds, and slightly in the same direction as the front wheels at higher speeds in order to increase stability.[14]

Without traditional steering

Steer-by-wire without the use of a steering column was first offered in a production car with the Nissan Infiniti Q50 in 2013.[4] The system has a backup steering column separated from the steering wheel with a clutch. The clutch connects the steering wheel to the steering rack in case of failure of the electronic steering sensors or actuators.[2] After negative reception the model was retrofitted with traditional hydraulic steering.[15] Steer-by-wire continued to be offered with the QX50 and QX55, and as of 2022 is being offered with the Infiniti Q60 coupe.[16]

Electric vehicles

Production battery electric vehicles (BEVs) with rear-axle SbW coupled with traditional front-wheel steering include the Rolls-Royce Spectre[17] and Lotus Eletre.[18]

Planned production BEVs as of 2023 that will offer steer-by-wire with no steering column include: Lexus RZ 450e,[19] Toyota bZ4X,[16] Canoo Lifestyle Vehicle,[20] REE Automotive P7-module-based vehicles,[21] and Geely Super Van.[22] As of 2023 Lotus,[18] Mercedes-Benz,[23] Nio,[24] Peugeot,[25] and purportedly Tesla[23] plan to offer no-steering-column steer-by-wire cars in the mid to late 2020s.

References

  1. SpeedE - Forschungsplattform, ika - Institute for Motor Vehicles of RWTH Aachen University, 2016
  2. Lutz Eckstein (2016), "Future Trends for Automotive Steering Systems" (PDF), JTEKT Engineering Journal English Edition (1013E)
  3. Chris Perkins (March 17, 2023), "How Toyota Is Making the Case for Steer-By-Wire", Road & Track
  4. Jancer, Matt. "Take a Look Inside the First Steer-by-Wire Car". Archived from the original on 2014-03-16. Retrieved 2017-03-06.
  5. Arunkumar Sampath, "Toward functional safety in drive by wire vehicles" (PDF), Mobility Engineering (December 2020)
  6. "Uniti Sweden: the diversity behind the electric car of the future", Euronews, April 8, 2017
  7. "First race participation of a GT3 without steering column on the Nordschleife". www.schaefflerparavan.de. 10 May 2021. Retrieved 1 October 2021.
  8. Bosch, Miguel (6 May 2021). "Schaeffler Paravan brings steer-by-wire system to GT3 with Mercedes-AMG entry in Nürburgring 24 Hours". www.gtreport.com. Retrieved 1 October 2021.
  9. Lydia Saß (July 26, 2023), "25 Jahre PARAVAN", barrierefrei-magazin.de
  10. Benjamin Hunting (January 5, 2021), "Why Did GM's Excellent Quadrasteer Full-Size Pickup Four-Wheel Steering System Simply Disappear?", DrivingLine
  11. Jonathon Klein (July 23, 2021), "How Exactly Does Four-Wheel Steering Work?", The Drive
  12. Daniel Golson (October 18, 2022), "Rolls-Royce Spectre EV Is the Brand's Most Important Car Yet", CNET
  13. Mark Vaughn (October 9, 2018), "Rolls-Royce Cullinan first drive: Seeing is believing", Autoweek
  14. Mark Ewing (October 25, 2017), "First Drive: Rolls-Royce Phantom VIII Has No Rival, Equal Or Peer", Forbes
  15. O'Kane, Tony (2 September 2014). "2016 Infiniti Q50 To Get 'Old Fashioned' Hydraulic Power Steering: Report". themotorreport.com.au. Archived from the original on 1 April 2017. Retrieved 13 April 2018.
  16. Jordan Golson (May 21, 2022), "What is Steer-by-Wire?", CapitalOne
  17. Britta O'Boyle (July 3, 2023), "Rolls-Royce Spectre review: The pinnacle of electric motoring", Pocket-lint
  18. Georg Kacher (July 10, 2023), "2024 Lotus Eletre review: First international drive", Which Car?
  19. Dave VanderWerp (September 20, 2023), "Lexus Continues to Hone Steer-by-Wire System, RZ Yoke Still a Year Away", Car and Driver
  20. Peter Corn (March 19, 2023), "This is What It Looks Like to Drive the Most Exciting EV, the Canoo Lifestyle Vehicle", MotorBiscuit
  21. Scooter Doll (May 2, 2023), "REE Automotive adds new P7-C chassis cab to its all-electric platform lineup", electrek
  22. "Chinese Farizon Auto launches its brand-new electric Super VAN, ready by 2024. Europe is the target", Sustainable Truck & Van, January 30, 2023
  23. Anthony Alaniz (July 3, 2023), "New Mercedes S-Class Could Have Yoke Steering Wheel, More Physical Buttons", Motor1.com
  24. Yang Jian (October 20, 2022), "ZF to supply steer-by-wire system to Nio", Automotive News
  25. Chris Chilton (January 6, 2023), "Hypersquare Steering On Road Cars By 2026, Peugeot CEO Says", Carscoops
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