With Time to Beat, Speeding Tickets to Avoid, Cruise Control kicks in Handy
It was one of those lazy weekends that I just wanted to stick my eyes on the television watching Natgeo, the best way to kill an afternoon. Around midday an buddy calls in, he has a meeting some 300 kms away with an investor who just confirmed the meeting twenty minutes ago and its the only window available. He tasks me with the responsibility to defy all odd sand drop in for the meeting in 2 hours. With countless signals and time to beat, speeding tickets are eminent. Lucky I remembered there are some buttons on my steering wheel which shows cruise control “maybe they will be my solution today” I thought.
Speed control with a centrifugal governor was used in automobiles as early as 1900 in the Wilson-Pilcher and also in the 1910s by Peerless. Peerless advertised that their system would “maintain speed whether uphill or down”. The technology was adopted to control steam engines, but the use of governors dates at least back to the 17th century. On an engine the governor adjusts the throttle position as the speed of the engine changes with different loads, so as to maintain a near constant speed.
Modern cruise control (also known as a speedostat or tempomat) was invented in 1948 by the inventor and mechanical engineer Ralph Teetor. His idea was born out of the frustration of riding in a car driven by his lawyer, who kept speeding up and slowing down as he talked. The system then calculated ground speed based on driveshaft rotations off the rotating speedometer-cable, and used a bi-directional screw-drive electric motor to vary throttle position as needed.
In 1965, American Motors (AMC) introduced a low-priced automatic speed control for its large-sized cars with automatic transmissions. The AMC “Cruise-Command” unit was engaged by a push-button once the desired speed was reached and then the throttle position was adjusted by a vacuum control directly from the speedometer cable rather than a separate dial on the dashboard
Three years down the line Daniel Aaron Wisner invented “Automotive Electronic Cruise Control” His invention described in two patents filed that year (US 3570622 & US 3511329), with the second modifying his original design by debuting digital memory, was the first electronic device in controlling a car. Two decades passed before an integrated circuit for his design was developed by Motorola. as the MC14460 Auto Speed Control Processor in CMOS. 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 cruise control takes its speed signal from a rotating driveshaft, speedometer cable, wheel speed sensor from the engine’s RPM, or from 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 40 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 be capable of being turned off both explicitly and automatically when the driver depresses the brake, and often also the clutch. Cruise control often includes 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 be used to accelerate the car, but once the pedal is released the car will then slow down until it reaches the previously set speed.
On the latest vehicles fitted with electronic throttle control, cruise control can be easily 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. This is an advantage for those driving in unfamiliar areas.
The cruise control systems of some vehicles incorporate a “speed limiter” function, which will not allow the vehicle to accelerate beyond a pre-set maximum; this can usually be overridden by fully depressing the accelerator pedal. Most systems will prevent the vehicle accelerating beyond the chosen speed, but will not apply the brakes in the event of overspeeding downhill.
On vehicles with a manual transmission, cruise control is less flexible because the act of 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 of most benefit at highway speeds when top gear is used virtually all the time.
Its usefulness for long drives helps reducing driver fatigue, improving comfort by allowing positioning changes more safely across highways and sparsely populated roads. Some drivers use it to avoid subconsciously violating speed limits. A driver who otherwise tends to subconsciously increase speed over the course of a highway journey may avoid speeding.
While more advance technology in vehicles has incorporated adaptive cruise control (ACC) systems, which is a general term meaning improved cruise control. These improvements can be automatic braking or dynamic set-speed type controls, while automatic braking type use either a radar or laser setup to allow the vehicle to keep pace with the car it is following, slow when closing in on the vehicle in front and accelerating again to the preset speed when traffic allows. Some systems also feature warning tailgating systems, which warn the driver if a vehicle in front is too close or decelerates faster than your vehicle.
On that Friday afternoon I only understood two buttons as “cruise controls”. But today me and you know how the system works. I do recommend that you visit your user manual before using it, to understands the whole operation on engagement and disengagement.