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Cruise control (also known as speed control, cruise command, autocruise, or tempomat) 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.
Speed control existed in early automobiles such as the Wilson-Pilcher in the early 1900s. They had a lever on the steering column that could be used to set the speed to be maintained by the engine. [1] In 1908, the Peerless included a governor to keep the speed of the engine through an extra throttle lever on the steering wheel. [2] Peerless successfully used a flyball governor. [3] They advertised their system as being able to "maintain speed whether uphill or down."
A governor was used by James Watt and Matthew Boulton in 1788 to control steam engines, but the use of governors dates at least back to the 17th century. On an engine, the governor uses centrifugal force to adjust the throttle position to adapt the engine's speed to different loads (e.g., when going up a hill).
Modern cruise control (also known as a speedostat or tempomat) was invented in 1948 by the blind inventor and mechanical engineer Ralph Teetor. [4] [5] He came up with the idea due to being frustrated by his driver's habit of speeding up and slowing down as he talked.
A more significant factor in developing cruise control was the 35 mph (56 km/h) speed limit imposed in the United States during World War II to reduce gasoline use and tire wear. [5] A mechanism controlled by the driver provided resistance to further pressure on the accelerator pedal when the vehicle reached the desired speed. [5] Teetor's idea of a dashboard speed selector with a mechanism connected to the driveshaft and a device able to push against the gas pedal was patented in 1950. [5] He added a speed lock capability that maintained the car's speed until the driver tapped the brake pedal or turned off the system. [5]
A 1955 U.S. patent for a "constant speed regulator" was filed in 1950 by M-Sgt Frank J. Riley. [6] He conceived the device while driving on the Pennsylvania Turnpike and installed his invention in his car in 1948. [7]
Another inventor named Harold Exline, working independently of Riley, also invented a type of cruise control that he first installed on his car and friends' cars. Exline filed a U.S. patent for a "vacuum powered throttle control with electrically controlled air valve" in 1951, which was granted in 1956. [8] Despite these patents, Riley, Exline, and subsequent patent holders were not able to collect royalties for any cruise control inventions.
The first car with Teetor's "speedostat" system was the 1958 Chrysler Imperial (called "auto-pilot"), using a speed control dial on the dashboard. [9] This system calculated ground speed from the rotating speedometer cable and used a bi-directional screw-drive electric motor to vary the throttle position as needed. Cadillac soon renamed and marketed the device as "cruise control." [5]
In 1965, American Motors Corporation (AMC) introduced a low-priced automatic speed control for its large-sized cars with automatic transmissions. [10] The AMC "cruise command" unit was actuated through a push-button on the dashboard once the car's desired speed was reached. The throttle position was automatically adjusted by a vacuum control that opened and closed the throttle based on input from the speedometer cable rather than through an adjustable control on the dashboard. [10] [11] The unit would shut off anytime the brakes were applied.
Daniel Aaron Wisner invented an "automotive electronic cruise control" in 1968 as an engineer for RCA's Industrial and Automation Systems Division in Plymouth, Michigan. His invention is described in two patents filed that year (US patents 3570622 and 3511329), with the second introducing digital memory, and was the first electronic device that controlled a car. [12]
Due to the 1973 oil crisis and rising fuel prices, the device became more popular in the U.S. [13] "Cruise control can save gas by avoiding surges that expel fuel" while driving at steady speeds. [13] In 1974, AMC, GM, and Chrysler priced the option at $60 to $70, while Ford charged $103. [13]
In the late 1980s, an integrated circuit for Wisner's design for electronic cruise control was finally commercially developed by Motorola as the MC14460 Automotive Speed Control Processor in CMOS. [14] The advantage of electronic speed control over its mechanical predecessor was that it could be integrated with electronic accident avoidance and engine management systems.
The driver must manually bring the vehicle up to speed and use a button to set the cruise control to the current speed.
The cruise control takes its speed signal from a rotating driveshaft, speedometer cable, wheel speed sensor from the engine's RPM, or internal speed pulses produced electronically by the vehicle. Most systems do not allow the use of the cruise control below a certain speed - typically around 25 or 30 mph (40 or 48 km/h). The vehicle will maintain the desired speed by pulling the throttle cable with a solenoid, a vacuum-driven servomechanism, or by using the electronic systems built into the vehicle (fully electronic) if it uses a 'drive-by-wire' system.
All cruise control systems must have the capability to be turned off explicitly and automatically when the driver depresses the brake pedal and often also the clutch. Cruise control systems frequently include a memory feature to resume the set speed after braking and a coast feature to reduce the set speed without braking. When the cruise control is engaged, the throttle can still accelerate the car, but once the pedal is released, it will slow down the vehicle until it reaches the previously set speed.
On the latest vehicles fitted with electronic throttle control, cruise control can be integrated into the vehicle's engine management system. Modern "adaptive" systems include the ability to automatically reduce speed when the distance to a car in front, or the speed limit, decreases.
The cruise control systems of some vehicles incorporate a "speed limiter" function, which will not allow the vehicle to accelerate beyond a preset maximum; this can usually be overridden by fully depressing the accelerator pedal. Most systems will prevent the vehicle from increasing engine speed to accelerate beyond the chosen speed. However, they will not apply the brakes in the event of overspeeding downhill, nor stop the car from going faster than the selected speed even with the engine just idling.
Cruise control is less flexible on vehicles with a manual transmission because depressing the clutch pedal and shifting gears usually disengages the cruise control. The "resume" feature has to be used each time after selecting the new gear and releasing the clutch. Therefore, cruise control is most beneficial at motorway/highway speeds when top gear is used virtually all the time. The speed limiter function, however, does not have this problem.
Some advantages of cruise control include: [15]
However, when misused, cruise control can lead to accidents due to several factors, such as: [15]
Some modern vehicles have adaptive cruise control (ACC) systems, a general term meaning improved cruise control. Dynamic set speed systems use the GPS position of speed limit signs from a database. Many systems also incorporate cameras, lasers, and millimeter-wave radar equipment to determine how close a vehicle is to others or other objects on the roadway. [20]
The technologies can be set to maintain a distance from vehicles in front of the car; the system will automatically slow down based on the vehicles in front or continue to keep the set speed. [20] Some systems cannot detect completely stationary cars or pedestrians, so the driver must always pay attention. Automatic braking systems use either a single or a combination of sensors (radar, lidar, and camera) to allow the vehicle to keep pace with the car it is following, slow when closing in on the vehicle in front, and accelerate to the preset speed when traffic allows. Some systems also feature forward collision warning systems, which warn the driver if a vehicle in front—given the speed of both vehicles—gets too close within the preset headway or braking distance.
Vehicles with adaptive cruise control are considered a Level 1 autonomous car, as defined by SAE International. [21]
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.
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.
In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An overdrive is sometimes mistakenly called a freewheel, but is otherwise unrelated.
A dashboard is a control panel set within the central console of a vehicle or cockpit of an aircraft or spacecraft. Usually located directly ahead of the driver, it displays instrumentation and controls for the vehicle's operation. An electronic equivalent may be called an electronic instrument cluster, digital instrument panel, digital dash, digital speedometer or digital instrument cluster.
Engine braking occurs when the retarding forces within an internal combustion engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes.
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.
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. Drive-by-wire may refer to just the propulsion of the vehicle through electronic throttle control, 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.
A direct-shift gearbox is an electronically controlled, dual-clutch, multiple-shaft, automatic gearbox, in either a transaxle or traditional transmission layout, with automated clutch operation, and with fully-automatic or semi-manual gear selection. The first dual-clutch transmissions were derived from Porsche in-house development for the Porsche 962 in the 1980s.
Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.
Hill descent control is a driver-assistance system allowing for a controlled hill descent in rough terrain without any brake input from the driver.
Launch control is an electronic aid to assist drivers of both racing and street cars to accelerate from a standing start. Motorcycles have been variously fitted with mechanical and electronic devices for both street and race.
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.
Clutch control refers to the act of controlling the speed of a vehicle with a manual transmission by partially engaging the clutch plate, using the clutch pedal instead of the accelerator pedal. The purpose of a clutch is in part to allow such control; in particular, a clutch provides transfer of torque between shafts spinning at different speeds. In the extreme, clutch control is used in performance driving, such as starting from a dead stop with the engine producing maximum torque at high RPM.
Electronic Diesel Control is a diesel engine fuel injection control system for the precise metering and delivery of fuel into the combustion chamber of modern diesel engines used in trucks and cars.
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.
The 2009–11 Toyota vehicle recalls involved three separate but related recalls of automobiles by the Japanese manufacturer Toyota Motor Corporation, which occurred at the end of 2009 and the start of 2010. Toyota initiated the recalls, the first two with the assistance of the U.S. National Highway Traffic Safety Administration (NHTSA), after reports that several vehicles experienced unintended acceleration. The first recall, on November 2, 2009, was to correct a possible incursion of an incorrect or out-of-place front driver's side floor mat into the foot pedal well, which can cause pedal entrapment. The second recall, on January 21, 2010, was begun after some crashes were shown not to have been caused by floor mat incursion. This latter defect was identified as a possible mechanical sticking of the accelerator pedal causing unintended acceleration, referred to as Sticking Accelerator Pedal by Toyota. The original action was initiated by Toyota in their Defect Information Report, dated October 5, 2009, amended January 27, 2010. Following the floor mat and accelerator pedal recalls, Toyota also issued a separate recall for hybrid anti-lock brake software in February 2010.
Sudden unintended acceleration (SUA) is the unintended, unexpected, uncontrolled acceleration of a vehicle, often accompanied by an apparent loss of braking effectiveness. Such problems may be caused by driver error, mechanical or electrical problems, or some combination of these factors. The US National Highway Traffic Safety Administration estimates 16,000 accidents per year in the United States occur when drivers intend to apply the brake but mistakenly apply the accelerator.
Synchronized downshift rev-matching system is a technology invented by Nissan for use on the Nissan 370Z. In combination with the Electronic Control Unit (ECU) and various sensors, the engine electronically blips the throttle for the driver during both downshifts and upshifts to allow for better and smoother shifting, and improved handling.
Car controls are the components in automobiles and other powered road vehicles, such as trucks and buses, used for driving and parking.