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→Positive and negative feedback
As an example of negative feedback, the diagram might represent a [[cruise control]] system in a car, for example, that matches a target speed such as the speed limit. The controlled system is the car; its input includes the combined torque from the engine and from the changing slope of the road (the disturbance). The car's speed (status) is measured by a [[speedometer]]. The error signal is the departure of the speed as measured by the speedometer from the target speed (set point). This measured error is interpreted by the controller to adjust the accelerator, commanding the fuel flow to the engine (the effector). The resulting change in engine torque, the feedback, combines with the torque exerted by the changing road grade to reduce the error in speed, minimizing the road disturbance.
As an example of negative feedback, the diagram might represent a [[cruise control]] system in a car, for example, that matches a target speed such as the speed limit. The controlled system is the car; its input includes the combined torque from the engine and from the changing slope of the road (the disturbance). The car's speed (status) is measured by a [[speedometer]]. The error signal is the departure of the speed as measured by the speedometer from the target speed (set point). This measured error is interpreted by the controller to adjust the accelerator, commanding the fuel flow to the engine (the effector). The resulting change in engine torque, the feedback, combines with the torque exerted by the changing road grade to reduce the error in speed, minimizing the road disturbance.
作为负反馈的一个例子，该图可能表示汽车中的[[巡航控制]]系统，例如，它与目标速度（如限速）相匹配。被控系统是汽车；它的输入包括来自发动机和来自道路坡度变化（干扰）的综合扭矩。汽车的速度（状态）由[[速度表]]测量。 误差信号是速度表测量的速度与目标速度（设定点）的偏差。该测量误差由控制器解释，以调整油门，命令燃油流向发动机（效应器）。由此产生的发动机扭矩的变化，即反馈，与变化的道路坡度所施加的扭矩相结合，减少速度的误差，使道路干扰降到最低。
20世纪后期的内燃机采用了机械反馈机制，如真空定时推进，但一旦小型、坚固和功能强大的单片机变得经济实惠，机械反馈就被电子发动机管理系统所取代。
20世纪后期的内燃机采用了机械反馈机制，如真空定时推进，但一旦小型、坚固和功能强大的单片机变得经济实惠，机械反馈就被电子发动机管理系统所取代。
===Other types of feedback===
===Other types of feedback===