PM861AK01 3BSE018157R6 Device for maintaining constant vehicle speed

An example of a control system is a constant-speed controller for a car, which is a device designed to keep a vehicle’s speed constant, desired or in reference to the speed provided by the driver. The controller is the cruise control plant is the car, and the system is the car and cruise control. The system output is the speed of the car, and the control itself is the throat of the engine where it determines how much power the engine puts out.

One of the original ways to implement cruise control is to simply lock the throttle position while the driver is using cruise control. But if cruise control is activated on an uneven stretch of road, the car will go slower going uphill and faster going downhill. This type of controller is called an open-loop controller because there is no feedback; No measurement of system output (car speed) is used to change control (throttle position). As a result, the controller cannot compensate for changes acting on the car, such as changes in the slope of the road.

The output y (t) of the system is measured by the sensor and the feedback F is compared with the reference value r (t). Controller C then accepts the error between the e reference and the output to change the system P under the input u control. As shown in the picture. This controller is a closed-loop controller or a feedback controller.

This is called a single input single output (SISO) control system; Multiple Input Multiple Output systems that have more than one input/output (i.e., multiple input-multiple output) are common. In this case, the variables pass through vectors rather than simple quantitative values. For some people the distributed parameter system vector may be infinite – spatial (usually functional).

In a closed-loop control system, data (system output) from sensors that monitor the vehicle’s speed enters the controller, which continuously compares a quantity representing speed with a reference quantity representing the desired speed. This difference is called the error and determines the throttle position (control). The result is to match the speed of the car to the reference speed (maintaining the desired system output). Now, when the car goes uphill, the difference between the input (detected speed) and the reference constantly determines the throttle position. When the detected speed is below the reference value, the difference increases, the throttle opens, the engine power increases, and the vehicle accelerates. In this way, the controller dynamically cancels out changes in the car’s speed. The central idea of these control systems is that the feedback loop controller affects the system output, which in turn is measured and fed back to the controller.