What are (Automatic) Controls?
Sensors measure a process and controllers adjust the process for optimal performance.
“The process looks good on paper until you get into the actuality of the application where feedback controls are a necessity.“
Input Sensors
In a typical feedback control system, sensors are used to measure various performance metrics of the device or system being controlled. These metrics could be anything from temperature and speed to pressure and humidity, depending on the application.
Data Processing
The collected data is then sent to a controller, which could be a microcontroller, PLC (Programmable Logic Controller), or even a software-based control algorithm running on a computer. The controller evaluates the sensor data against a set of desired outcomes or setpoints.
Process Control
If the controller determines that the performance metrics are not aligned with the desired outcomes, it will generate control signals to adjust the actuators. These actuators could be motors, valves, or any other devices capable of affecting changes in the system. The adjustments are made to bring the performance metrics closer to the setpoints.
Feedback Loop
This is a continuous, iterative process. The sensors keep measuring, and the controller keeps adjusting, in real-time, to maintain the system in its desired state.
These feedback loops can become quite complex, especially when multiple sensors and actuators are involved, or when the system has to adapt to varying external conditions.
Advanced Algorithms
Advanced control algorithms, network protocols, and data analytics often come into play to ensure efficient and accurate performance.

Common Controls used in Automation:
- Digital – Input & Output
Basic traditional mechatronics machines.
Including NPN and PNP style devices. - Analog – Input & Output
Analog control offers enhanced precision.
Includes 4-20mA, thermal, and optical devices. - HMI
Human Machine Interface – Can be as simple as a few lights and buttons to computerized touchscreen interfaces. - PID
Proportional, Integral, Derivative – Controllers use this feedback loop algorithm to continuously control processes. - PLC
Programmable Logic Controller – The controller of modern automation systems. - PWM
Pulse Width Modulation – Method of controlling the average power by rapid switching on and off to achieve a percentage of full power. - Servo
Servo Motor Controller – DC servo motor control with position encoder feedback sensor. - Stepper
Stepper Motor Controller – Specialized multi-phase motor control. - VFD
Variable Frequency Drive – Controls a motors speed and torque by varying the frequency of the electricity sent to AC motors.