Drive by wire or DbW technology in the automotive industry is the use of electrical or electro-mechanical systems for performing vehicle functions traditionally achieved by mechanical linkages. Common examples include power steering, electronic throttle control and brake-by-wire. These technologies replace the traditional mechanical control systems with electronic control systems using electromechanical actuators and human–machine interfaces such as pedal and steering feel emulators. Components such as the steering column, intermediate shafts, pumps, hoses, belts, coolers and vacuum servos and master cylinders are eliminated from the vehicle. This is similar to the fly-by-wire systems used widely in the aviation industry. Safety standards for drive-by-wire are specified by the ISO 26262 standard level D.
Properties
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The electronic throttle system is significantly lighter, reducing weight in modern cars. They are easier to service and tune, as a technician can simply connect a computer and let the computer perform the tuning. Using an electronic control system also allows for much more precise control of the throttle opening compared to a cable that stretches over time. It also allows the throttle response to be programmed in by the manufacturers.
Because the steering wheel can be bypassed as an input device, safety can be improved by providing computer controlled intervention of vehicle controls with systems such as electronic stability control (ESC), adaptive cruise control and Lane Assist Systems. Some systems, with appropriate modification, allow for control by laptops or even game controllers.[1]
Ergonomics can be improved by the amount of force and range of movement required by the driver and by greater flexibility in the location of controls. This flexibility also significantly expands the number of options for the vehicle's design.
Each drive-by-wire system leads to more motors in the vehicle and therefore a greater energy consumption. For instance, the drive-by-wire technology adds actuator motors to create the torque needed to turn the wheels, and a feedback transducer to create the "road feel" on the steering wheel.
Safety and security
Research about the safety of drive-by-wire systems has been ongoing since 2011 at the Aachen University Institute for Motor Vehicles (ika - Institut für Kraftfahrzeuge) in collaboration with Mercedes-AMG and others. Failures in drive by wire systems can lead to potential hazardous situations where safety depends entirely on the vehicle's failure mode. Several papers published by the institute detail the operation, risks, and safety mechanisms of its concept vehicle's drive-by-wire systems. Scenarios include loss of control over acceleration, brakes, or steering. The institute's concept vehicle, SpeedE, was designed to avoid safety through redundancy in many of its systems, though a redundant mechanical braking system was implemented.[2] Contrarily, the modern drive by wire paradigm replaces mechanical fail-safes with redundancy fail-safes and other security measures: computational redundancy through lockstep CPUs; functional redundancy through modular design where the failure of one module is compensated by an identical module, for example by torque vectoring to compensate for a failed steering or braking module; multi-sensor fault detection; self-isolation of damaged systems; and fault-tolerant communication. Such fail-safes are specified by the ISO 26262 standard level D.[3]
Assessment and standardization of drive-by-wire computer security has also taken place. Researchers demonstrated in 2011[4] and 2013[5][6] that some systems in commercially-available vehicles are susceptible to hacking, allowing for external control of the vehicle. Hacking demonstrations included remote activation of systems like the horn, windshield wipers, accelerator, brakes, and transmission.[6] Modern standards such as the ISO/SAE 21434 standard and UNCE regulations 155, 156, and 157 require dedicated cryptographic modules that encrypt all communication between the ECUs and the drive system components.[7]
Systems
Throttle by wire
This system helps accomplish vehicle propulsion by means of an electronic throttle without any cables from the accelerator pedal to the throttle valve of the engine. In electric vehicles, this system controls the electric motors by sensing the accelerator pedal input and sending commands to the power inverter modules.
Brake by wire
A pure brake by wire system would eliminate the need for hydraulics completely by using motors to actuate calipers, in comparison to the currently existing technology where the system is designed to provide braking effort by building hydraulic pressure in the brake lines.
Shift by wire
The direction of motion of the vehicle (Forward, Reverse) is set by commanding the actuators inside the transmission through electronic commands based on the current input from the driver (Park, Reverse, Neutral or Drive).
Steer by wire
A car equipped with a steer-by-wire system is able to steer without a steering column.[8] The control of the wheels' direction will be established through electric motors which are actuated by ECUs monitoring the steering wheel inputs from the driver.[9] Rear-axle-only steer-by-wire may be couple with traditional front wheel steering for conditional four-wheel steering, reducing turning radius at low speeds and adding stability at high speeds.[10]
Quadrasteer was a rear-axle-only steer-by-wire system couple with traditional front steering. It was developed by Delphi and 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, partially due to lack of familiarity with the system and partially due to its $1000 mark-up.[10]
Full steer-by-wire in a production car was first offered with the Infiniti Q50 in 2013,[9] but after negative reception the model was retrofitted with traditional hydraulic steering.[11]
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.[citation needed] 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.[12][13]
Production battery electric vehicles that offer steer-by-wire include the 2023 Lexus RZ which has full steer-by-wire,[14] Rolls-Royce Spectre which has rear-axle SbW coupled with front-wheel steering,[15] and full steer-by-wire REE Automotive P7-module-based vehicles.[16] Toyota, Mercedes-Benz, and purportedly Tesla plan to offer steer-by-wire cars in the mid to late 2020s.[17]
Park by wire
The parking pawl in a traditional automatic transmission has a mechanical link to the gear lever and locks the transmission in the park position when the vehicle is set in Park. A park by wire system uses electronic commands to actuate the parking pawl by a motor when the driver puts the vehicle in park.
References
- ^ "I used a PS4 controller to drive a car". TechRadar. 12 October 2017. Archived from the original on 2018-08-03. Retrieved 2018-08-03.
- ^ SpeedE - Forschungsplattform, ika - Institute for Motor Vehicles of RWTH Aachen University, 2016
- ^ Arunkumar Sampath, "Toward functional safety in drive by wire vehicles" (PDF), Mobility Engineering (December 2020)
- ^ Checkoway, Stephen. "Comprehensive Experimental Analyses of Automotive Attack Surfaces". YouTube. Archived from the original on 31 May 2017. Retrieved 23 August 2018.
- ^ Greenberg, Andy. "Hackers Reveal Nasty New Car Attacks--With Me Behind The Wheel (Video)". Archived from the original on 2017-08-25. Retrieved 2017-08-26.
- ^ a b Greenberg, Andy. "Hackers Remotely Kill a Jeep on the Highway—With Me in It". Archived from the original on 2017-01-19. Retrieved 2017-03-06.
- ^ Scheibert, K., Kostarigka, A., Dannebaum, U., Ambekar, A. et al., "Challenges with the Introduction of X-By-Wire Technologies to Passenger Vehicles and Light Trucks in regards to Functional Safety, Cybersecurity and Availability," SAE Technical Paper 2023-01-0581, 2023, doi: 10.4271/2023-01-0581 .
- ^ "Steer By Wire". Archived from the original on 2013-12-20. Retrieved 2013-12-19.
- ^ a b Jancer, Matt. "Take a Look Inside the First Steer-by-Wire Car". Archived from the original on 2014-03-16. Retrieved 2017-03-06.
- ^ a b Benjamin Hunting (January 5, 2021), "Why Did GM's Excellent Quadrasteer Full-Size Pickup Four-Wheel Steering System Simply Disappear?", DrivingLine
- ^ 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.
- ^ "First race participation of a GT3 without steering column on the Nordschleife". www.schaeffler‑paravan.de. 10 May 2021. Retrieved 1 October 2021.
- ^ Bosch, Miguel (6 May 2021). "Schaeffler Paravan brings steer-by-wire system to GT3 with Mercedes-AMG entry in Nürburgring 24 Hours". www.gt‑report.com. Retrieved 1 October 2021.
- ^ Aaron Gold (May 2, 2022), "2023 Lexus RZ Steer-by-Wire Steering Yoke Review: This Yoke Is No Joke", MotorTrend
- ^ Britta O'Boyle (July 3, 2023), "Rolls-Royce Spectre review: The pinnacle of electric motoring", Pocket-lint
- ^ Scooter Doll (May 2, 2023), "REE Automotive adds new P7-C chassis cab to its all-electric platform lineup", electrek
- ^ Anthony Alaniz (July 3, 2023), "New Mercedes S-Class Could Have Yoke Steering Wheel, More Physical Buttons", Motor1.com