Drive by wire

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SpeedE, an academic concept car developed for studying drive-by-wire technologies Erprobungsfahrzeug SpeedE der fka GmbH.jpg
SpeedE, an academic concept car developed for studying drive-by-wire technologies

Drive by wire or DbW technology in the automotive industry is the use of electronic or electro-mechanical systems in place of mechanical linkages that control driving functions. The concept is similar to fly-by-wire in the aviation industry. [2] Drive-by-wire may refer to just the propulsion of the vehicle through electronic throttle control, [3] or it may refer to electronic control over propulsion as well as steering and braking, which separately are known as steer by wire and brake by wire, along with electronic control over other vehicle driving functions. [4]

Contents

Driver input is traditionally transferred mechanically to the motor and wheels through a steering wheel and steering column, throttle, hydraulic brakes, brake pull handles and so on. In drive-by-wire systems, driver input is processed by an electronic control system which controls the vehicle using electromechanical actuators. The human–machine interface, such as a steering wheel, yoke, accelerator pedal, brake pedal, and so on, may include haptic feedback that simulates the resistance of hydraulic and mechanical pedals and steering, including steering kickback. Components such as the steering column, intermediate shafts, pumps, hoses, belts, coolers, vacuum servos and master cylinders are eliminated from the vehicle. Safety standards for drive-by-wire are specified by the ISO 26262 standard level D.

Properties

The REE P7-C truck is the first commercially available vehicle to be road-certified in the United States with all by-wire controls, including drive, steer, brake, and park-brake by-wire, collectively called x-by-wire. REE Automotive P7-C class 4 electric truck with Knapheide vocational body Work Truck Week 2024 facing left.jpg
The REE P7-C truck is the first commercially available vehicle to be road-certified in the United States with all by-wire controls, including drive, steer, brake, and park-brake by-wire, collectively called x-by-wire.

Dispensing with mechanical linkages has several advantages: it reduces complexity and simplifies assembly; simplifies service and tuning; reduces the force required to engage inputs and allows it to be customized with haptic technology; allows for more interior design freedom in the placement of input mechanisms; allows for automation of driving functions; reduces cabin noise by eliminating the acoustic linkage to the drive systems; and by reducing floor openings it improves the crash behavior of the vehicle. [6] Because driver inputs can be overridden, 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. [2]

Each drive-by-wire system leads to more actuator in the vehicle and therefore 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 considerations require redundancy of driver input sensors, vehicle communication networks, actuators, [6] and other systems. Automotive safety standards such as ISO 26262 require drive-by-wire fail-operational and fail-safe behaviors. [7]

Safety and security

Failures in drive by wire systems can lead to potential hazardous situations where safety depends entirely on the vehicle's failure mode. The Aachen University Institute for Motor Vehicles (ika – Institut für Kraftfahrzeuge Aachen), in collaboration with Mercedes-AMG and others, studies the operation, risks, and safety mechanisms of drive-by-wire systems through its drive-by-wire concept vehicle, SpeedE. Studied scenarios include loss of control over acceleration, brakes, or steering. [1]

Early by-wire systems had mechanical backup systems in case the by-wire systems failed. [3] The modern drive by wire paradigm dispenses with mechanical backups, and relies on redundancy, fail-operational systems, and other safety and 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. [7]

Assessment and standardization of drive-by-wire computer security has also taken place. Researchers demonstrated in 2011 [8] and 2013 [9] [10] 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. [10] 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. [3]

Systems

A model of the Lotus Eletre with drive-, steer-, and brake-by-wire provided by ZF Group is planned for 2025 Lotus Eletre 010 (cropped).jpg
A model of the Lotus Eletre with drive-, steer-, and brake-by-wire provided by ZF Group is planned for 2025

Brake by wire

A brake-by-wire system eliminates the need for a mechanical connection that transfers force between the brakes and a driver input apparatus such as a pedal or lever. The three main types of brake-by-wire systems are: electronic parking brakes which have, since the turn of the 21st century, become more common; electro-hydraulic brakes (EHB) which can be implemented alongside legacy hydraulic brakes and as of 2020 have found small-scale usage in the automotive industry; and electro-mechanical brakes (EMB) that use no hydraulic fluid, which as of 2020 have yet to be successfully introduced in production vehicles due to their novel actuation methods. [13]

Shift by wire

Shift-by-wire employs electrical or electronic connections that replace the mechanical connection between the driver's gearshift mechanism and the transmission. Since becoming commercially available in 1996, shift-by-wire has been commonly used in automated manual transmission, and has later been implemented in semi-automatic transmission and automatic transmission. [6]

Park by wire may be considered a form of shift-by-wire. [6] Not to be confused with park-brake by wire which engages a parking brake, park-by-wire engages the parking pawl. A parking pawl in a traditional automatic transmission has a mechanical link to the gear stick and locks the transmission in the park position when the gear-shift handle is set in "park". A park-by-wire system uses electronic commands sent to an actuator that engages the parking pawl.

Steer by wire

Up-fitted drive-by-wire systems, such as the Paravan Space Drive, have been available since as early as 2003 for existing production vehicles. [14]

A vehicle equipped with a steer-by-wire system is able to steer some or all of its 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 mechanically transfer some steering torque to the wheels. [15]

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 and steer 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. [15] [16]

Throttle by wire

Accelerate-by-wire or throttle-by-wire, [17] more commonly known as electronic throttle control, is a system that actuates vehicle propulsion without any mechanical connections, such as cables, from the accelerator pedal to the throttle valve of the engine or other propulsion systems. In electric vehicles, this system controls the electric motors by sensing the accelerator pedal input and sending commands to the power inverter modules.

Related Research Articles

<span class="mw-page-title-main">Anti-lock braking system</span> Safety anti-skid braking system used on aerospace and land vehicles

An anti-lock braking system (ABS) is a safety anti-skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses. ABS operates by preventing the wheels from locking up during braking, thereby maintaining tractive contact with the road surface and allowing the driver to maintain more control over the vehicle.

<span class="mw-page-title-main">Cruise control</span> System that automatically controls the speed of a motor vehicle

Cruise control is a system that automatically controls the speed of an automobile. The system is a servomechanism that takes over the car's throttle to maintain a steady speed set by the driver.

<span class="mw-page-title-main">Automatic transmission</span> Type of motor vehicle transmission that automatically changes gear ratio as the vehicle moves

An automatic transmission is a multi-speed transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. Vehicles with internal combustion engines, unlike electric vehicles, require the engine to operate in a narrow range of rates of rotation, requiring a gearbox, operated manually or automatically, to drive the wheels over a wide range of speeds.

A traction control system (TCS), is typically a secondary function of the electronic stability control (ESC) on production motor vehicles, designed to prevent loss of traction of the driven road wheels. TCS is activated when throttle input and engine power and torque transfer are mismatched to the road surface conditions.

<span class="mw-page-title-main">Manual transmission</span> Motor vehicle manual gearbox; stick shift

A manual transmission (MT), also known as manual gearbox, standard transmission, or stick shift, is a multi-speed motor vehicle transmission system, where gear changes require the driver to manually select the gears by operating a gear stick and clutch.

<span class="mw-page-title-main">Electronic brakeforce distribution</span>

Electronic brakeforce distribution or electronic brakeforce limitation (EBL) is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's wheels, based on road conditions, speed, loading, etc, thus providing intelligent control of both brake balance and overall brake force. Always coupled with anti-lock braking systems (ABS), EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control. Typically, the front end carries more weight and EBD distributes less braking pressure to the rear brakes so the rear brakes do not lock up and cause a skid. In some systems, EBD distributes more braking pressure at the rear brakes during initial brake application before the effects of weight transfer become apparent.

<span class="mw-page-title-main">Electronic throttle control</span> Automobile technology

Electronic throttle control (ETC) is an automobile technology that uses electronics to replace the traditional mechanical linkages between the driver's input such as a foot pedal to the vehicle's throttle mechanism which regulates speed or acceleration. This concept is often called drive by wire, and sometimes called accelerate-by-wire, throttle-by-wire, and occasionally e-gas by some vehicle components manufacturers.

<span class="mw-page-title-main">Automated manual transmission</span> Type of multi-speed motor vehicle transmission system

The automated manual transmission (AMT) is a type of transmission for motor vehicles. It is essentially a conventional manual transmission equipped with automatic actuation to operate the clutch and/or shift gears.

<span class="mw-page-title-main">Parking brake</span> Secondary automotive braking system

In road vehicles, the parking brake, also known as a handbrake or emergency brake (e-brake), is a mechanism used to keep the vehicle securely motionless when parked. Parking brakes often consist of a pulling mechanism attached to a cable which is connected to two wheel brakes. In most vehicles, the parking brake operates only on the rear wheels, which have reduced traction while braking. The mechanism may be a hand-operated lever, a straight pull handle located near the steering column, or a foot-operated pedal located with the other pedals.

A transmission control unit (TCU), also known as a transmission control module (TCM), or a gearbox control unit (GCU), is a type of automotive ECU that is used to control electronic automatic transmissions. Similar systems are used in conjunction with various semi-automatic transmissions, purely for clutch automation and actuation. A TCU in a modern automatic transmission generally uses sensors from the vehicle, as well as data provided by the engine control unit (ECU), to calculate how and when to change gears in the vehicle for optimum performance, fuel economy and shift quality.

The following outline is provided as an overview of and topical guide to automobiles:

<span class="mw-page-title-main">Brake-by-wire</span> Automotive technology

Brake-by-wire technology in the automotive industry is the ability to control brakes through electronic means, without a mechanical connection that transfers force to the physical braking system from a driver input apparatus such as a pedal or lever.

By-wire refers to technologies in which a system is controlled using electrical or electronic means rather than by a mechanical linkage that transfers force from the input to the system. The concept is used in aviation and in the automotive industry. By analogy, it may refer to managing by wire, a management style relying on an informational representations of the business, similar to fly-by-wire pilots who rely on an informational representation of the plane.

<span class="mw-page-title-main">Steer-by-wire</span> Automotive technology

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 that turns the direction of those wheels mechanically. 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. It is often associated with other drive by wire technologies.

S-AWC is the brand name of an advanced full-time four-wheel drive system developed by Mitsubishi Motors. The technology, specifically developed for the new 2007 Lancer Evolution, the 2010 Outlander, the 2014 Outlander, the Outlander PHEV and the Eclipse Cross have an advanced version of Mitsubishi's AWC system. Mitsubishi Motors first exhibited S-AWC integration control technology in the Concept-X model at the 39th Tokyo Motor Show in 2005. According to Mitsubishi, "the ultimate embodiment of the company's AWC philosophy is the S-AWC system, a 4WD-based integrated vehicle dynamics control system".

All Wheel Control (AWC) is the brand name of a four-wheel drive (4WD) system developed by Mitsubishi Motors. The system was first incorporated in the 2001 Lancer Evolution VII. Subsequent developments have led to S-AWC (Super All Wheel Control), developed specifically for the new 2007 Lancer Evolution. The system is referred by the company as its unique 4-wheel drive technology umbrella, cultivated through its motor sports activities and long history in rallying spanning almost half a century.

<span class="mw-page-title-main">Line lock</span> Vehicle braking technology

A line lock is a device that allows the front brakes to lock independently of the rear brakes via a switch. The device is an electric solenoid that controls a valve which allows the brakes to be controlled individually. This allows the front brakes to be locked and the rear brakes to be open, and allows the driver to spin the rear wheels without wasting the rear brakes. This method is referred to as line lock and is popular among enthusiasts who like to do burnouts.

<span class="mw-page-title-main">Shift-by-wire</span>

Shift-by-wire is an automotive concept or system that employs electrical or electronic connections that replace the mechanical connection between the driver's gearshift mechanism and the transmission. Since becoming commercially available in 1996, shift-by-wire has been commonly used in automated manual transmission and has later been implemented in semi-automatic transmission and automatic transmission.

<span class="mw-page-title-main">Car controls</span> Car parts used to control the vehicle

Car controls are the components in automobiles and other powered road vehicles, such as trucks and buses, used for driving and parking.

This glossary of automotive terms is a list of definitions of terms and concepts related to automobiles, including their parts, operation, and manufacture, as well as automotive engineering, auto repair, and the automotive industry in general. For more specific terminology regarding the design and classification of various automobile styles, see Glossary of automotive design; for terms related to transportation by road, see Glossary of road transport terms; for competitive auto racing, see Glossary of motorsport terms.

References

  1. 1 2 SpeedE – Forschungsplattform, ika – Institute for Motor Vehicles of RWTH Aachen University, 2016
  2. 1 2 Austin Weber (March 26, 2010), "Wire Processing: Drive-by-Wire", Assembly Magazine
  3. 1 2 3 4 Scheibert, Klaus; Kostarigka, Artemis; Dannebaum, Udo; Ambekar, Abhijit; Cai, Wenlin; Heidt, Laurent (2023). "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 Series. Vol. 1. doi:10.4271/2023-01-0581. S2CID   258033364.
  4. ↑ Pillai, Arjun V.; Manojkumar, B. (2022). "Overview of drive by wire technologies in automobiles". INTERNATIONAL CONFERENCE ON TRENDS IN CHEMICAL ENGINEERING 2021 (ICoTRiCE2021). AIP Conference Proceedings. Vol. 2452. p. 030001. Bibcode:2022AIPC.2452c0001P. doi:10.1063/5.0113232. S2CID   253697706.
  5. ↑ Chris Rosamond (January 12, 2024), "World first 'everything-by-wire' vehicle breaks all mechanical links to driver", Auto Express
  6. 1 2 3 4 Harald Naunheimer; et al. (2011), "9.1.3 Shift-by-Wire", Automotive Transmissions: Fundamentals, Selection, Design and Application (Second ed.), Springer, doi:10.1007/978-3-642-16214-5, ISBN   978-3-642-16213-8
  7. 1 2 Arunkumar Sampath, "Toward functional safety in drive by wire vehicles" (PDF), Mobility Engineering (December 2020)
  8. ↑ Checkoway, Stephen. "Comprehensive Experimental Analyses of Automotive Attack Surfaces". YouTube. Archived from the original on May 31, 2017. Retrieved August 23, 2018.
  9. ↑ Greenberg, Andy. "Hackers Reveal Nasty New Car Attacks—With Me Behind The Wheel (Video)". Forbes . Archived from the original on August 25, 2017. Retrieved August 26, 2017.
  10. 1 2 Greenberg, Andy. "Hackers Remotely Kill a Jeep on the Highway—With Me in It". Wired. Archived from the original on January 19, 2017. Retrieved March 6, 2017.
  11. ↑ ZF presents MOBILITY by-wire technology at IAA, 2023
  12. ↑ Georg Kacher (July 10, 2023), "2024 Lotus Eletre review: First international drive", Which Car?
  13. ↑ Dieter Schramm; et al. (2020), "5 Braking systems", Vehicle Technology: Technical foundations of current and future motor vehicles, De Gruyter Oldenbourg, doi:10.1515/9783110595703, ISBN   9783110595703, S2CID   216374738
  14. ↑ Lydia Saß (July 26, 2023), "25 Jahre PARAVAN", barrierefrei-magazin.de
  15. 1 2 Chris Perkins (March 17, 2023), "How Toyota Is Making the Case for Steer-By-Wire", Road & Track
  16. ↑ Jancer, Matt. "Take a Look Inside the First Steer-by-Wire Car". Wired. Archived from the original on March 16, 2014. Retrieved March 6, 2017.
  17. ↑ John Fuller (April 28, 2009), "How Drive-by-wire Technology Works", HowStuffWorks
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