A Cloud In TheSky

Controlling the environment in a room can be tricky. Often it's based on an economic viewpoint. I will try explaining different sensors and outputs and what I've seen used practically with good results.

I will try explaining “Best Practice” or “Ideas of best practice” below with increasing advancements.

Simplest automation, is a room temperature sensor controlling room heating. Heat setpoint at 23 °C, and when room temperature gets below this setpoint, you can start regulation your heat option.

Regulators can be a difficult subject that requires a comprehensive explaination. For now I'll just explain 2 types.

Control curves can be 2 points and upwards (Often no more then 10 points) For heating, imagine 2 points in a curve, where X is the temperature below setpoint eg. 10 to 0 degrees below, and Y is a percentage from 100% to 0%. See the graph below.

PID regulators is a bit more difficult to explain and understand. They use more system resources so often the control curve is preferred if the system is low on resources.

I'll try a simple explanation first: If the temperature (Control variable) gets below setpoint, the regulator will increase the heating (Output variable)

On Wikipedia there's a lot of information about this regulator, but I will highlight one thing from there, a pseudo code examble.

• Kp - proportional gain
• Ki - integral gain
• Kd - derivative gain
• dt - loop interval time
• previous_error := 0
• integral := 0

loop:
error := setpoint − measured_value
proportional := error;
integral := integral + error × dt
derivative := (error − previous_error) / dt
output := Kp × proportional + Ki × integral + Kd × derivative
previous_error := error
wait(dt)
goto loop

A sensor is basically anything inbound information, from temperature to light status.