IntermediateTopic 45 of 101Signals, Control & Comms
Plant, sensor, controller, actuator
The main blocks in a feedback loop.
In depth
A feedback loop includes the plant (process being controlled), sensor (measurement, with noise and delay), controller (computes control action) and actuator (applies it). Each has dynamics and limits (saturation, rate limits). Understanding each block is vital for performance and safety.
Key points
- Signal chain
- Saturation and windup
- Sensor placement
ExampleIn a drone: IMU sensor, flight controller, motor drivers (actuators) and airframe (plant).
The main blocks of a feedback loop are the plant, sensor, controller and actuator, and knowing each one shows where a fault or limit lies.
What is Plant, sensor, controller, actuator?
The main blocks in a feedback loop.
Why is it important to understand plant, sensor, controller, actuator?
The main blocks of a feedback loop are the plant, sensor, controller and actuator, and knowing each one shows where a fault or limit lies.
What is the plant?
The physical system being controlled, such as a motor, a tank or a vehicle.
What does the actuator do?
It converts the controller command into a physical effect, such as a valve opening or a motor torque.
How is Plant, sensor, controller, actuator used in practice?
Typical applications include identifying which block limits the response of a robot arm, checking whether a sensor delay is the cause of oscillation and choosing an actuator that can deliver the power the plant needs.
What should I learn before Plant, sensor, controller, actuator?
Study "Open-loop vs closed-loop" first (topic 44 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Plant, sensor, controller, actuator?
Signal chain. Saturation and windup. Sensor placement.
Can you give an example of Plant, sensor, controller, actuator?
In a drone: IMU sensor, flight controller, motor drivers (actuators) and airframe (plant).
What comes after Plant, sensor, controller, actuator?
The next topic is "Modelling mechanical and electrical systems", which builds directly on this one.
How difficult is Plant, sensor, controller, actuator?
It is classed as Intermediate in Signals, Control & Comms (topic 45 of 101). It is an intermediate topic. Work through the beginner topics in Signals, Control & Comms first.