The design of closed loop control systems is comparatively more complex than open ones. Such system takes feedback from outut and performs the required action accordingly. The entire construction requires a sensor for taking input, some sort of controller which performs the action and a feedback taken from the output. Given below are 10 examples of closed loop control systems.
Contents
Thermostat Heater
The thermostat heater is an example of closed loop control system. The thermostat senses the temperature of the system and maintains the temperature.
| Thermostat heater | |
|---|---|
| Input | Temperature |
| Plant | Heater |
| Controller | Thermostat |
| Output | Temperature |
Sunseeker solar system
Sunseeker solar system is an automatic tracker which uses LDR to sense the sunlight. A microcontroller reads the LDR voltage and signals the connected motor which rotates the panel towards the sun.
| Sunseeker solar system | |
|---|---|
| Input | Sunlight |
| Plant | Solar Panel |
| Controller | µC |
| Output | Position change |
Voltage stabilizer
The voltage stabilizer stabilizes the supply voltage in case of fluctuations. Modern voltage stabilizers utilize solid state electronic components which measure the fluctuation in voltage and reduce/increase (buck/boost) the voltage to the desired level.
| Voltage Stabilizer | |
|---|---|
| Input | Voltage |
| Plant | Stabilizer |
| Controller | Electronic Circuit |
| Output | Voltage Buck/Boost |
Missile Launcher
A missile launcher detects the position of the plane using radar tracking unit and then
| Voltage Stabilizer | |
|---|---|
| Input | Position |
| Plant | Launcher |
| Controller | Computer system |
| Output | Target |
Auto Engine
The tachometer in auto engine generates a voltage proportional to the speed of the shaft. The voltage is subtracted from the input voltage to calculate an error voltage that provides information about current speed and desired speed. The error voltage is then used to arrange the throttle after amplification.
| Auto Engine | |
|---|---|
| Input | Desired speed |
| Plant | Auto Engine |
| Controller | Cruise system |
| Output | Change in speed |
Inverter AC
The inverter air conditioner uses an inverter for controlling the compressor speed. Sensors measure the ambient air temperature and then adjust compressor to the required level.
| Inverter AC | |
|---|---|
| Input | Temperature |
| Plant | AC |
| Controller | Inverter inside VFD |
| Output | Change in speed |
Automatic toaster
The automatic toaster measures the temperature, moisture vs dryness level of toast and adjusts the heat setting of toasts.
| Automatic toaster | |
|---|---|
| Input | Moisture level |
| Plant | Toaster |
| Controller | Heat setting circuitry |
| Output | Heat level |
Turbine Water Control System at power Station
In modern hydroelectric power stations, the level of water coming from the nozzles and gate is adjusted using automatic controls.
| Turbine water control | |
|---|---|
| Input | Flow rate of water |
| Plant | DAM |
| Controller | Governor sets |
| Output | Change of flow rate |
Automatic Clothes Iron
The automatic clothes iron adjusts the required temperature for proper pressing. An automatic iron regulates the temperature of iron itself in such a way that the temperature for a cloth stays in specified temperature range.
| Automatic clothes iron | |
|---|---|
| Input | Desired Temperature |
| Plant | Automatic Iron |
| Controller | Thermostat |
| Output | Temperature |
- Input: The desired temperature setting is the input to the system. It represents the target temperature at which the iron should operate.
- Process: The process refers to the iron’s heating element, which converts electrical energy into heat. The heating element is responsible for raising the iron’s temperature.
- Output: The output is the actual temperature of the iron. It represents the current temperature of the iron, which should ideally match the desired temperature.
- Sensor: The iron employs a temperature sensor, such as a thermostat, to measure the actual temperature of the iron.
- Controller: The controller is responsible for comparing the desired temperature (input) with the actual temperature (output) measured by the sensor. It calculates the error, which is the difference between the desired temperature and the actual temperature.
- Actuator: The actuator in this case is the control mechanism that adjusts the heating element’s power based on the controller’s instructions. It controls the heat generation in response to the error signal.
- Feedback: The feedback loop is established by the sensor, which continuously monitors the temperature of the iron. It provides the necessary information about the system’s current state.
Sequence of Work for Automatic Clothes Iron closed-loop control system:
- The desired temperature is set by the user, serving as the reference input.
- The temperature sensor measures the actual temperature of the iron.
- The controller calculates the error by comparing the desired temperature with the actual temperature.
- Based on the error signal, the controller sends instructions to the actuator, which adjusts the power supplied to the heating element.
- The heating element responds to the actuator’s instructions and either increases or decreases heat generation accordingly.
- The temperature sensor continues to monitor the temperature, providing feedback to the controller.
- The controller adjusts the actuator’s instructions based on the feedback, aiming to minimize the error and bring the actual temperature closer to the desired temperature.
- This feedback loop continues until the actual temperature matches the desired temperature, at which point the controller maintains the temperature by fine-tuning the heating element’s power.
A human traveling on the road
The human body itself is the perfect example of closed-loop control systems. He looks around for traffic and changes his position accordingly.
| Human traveling on the road | |
|---|---|
| Input | Information about surrounding |
| Plant | Human |
| Controller | Brain |
| Output | Position adjustment |