Deadband and Hysteresis values from graphs

[Uros11]

Hello,

So I was learning about on-off control and three position control, and I found some tasks about values of deadband and hysteresis that I simply cannot understand, and see exactly what is going on. I would like if someone can explain which points should I look at. The exact task is what are the values of B (deadband) and H (hysteresis).

 

[kripacharya]

Deadband is that set of input values where no action is taken one way or another.

Hysteresis is when one 'trip point' causes another 'trip point' to be changed so that it is in opposition to the signal movement.

 

[andre_luis]

The exact task is what are the values of B (deadband) and H (hysteresis)

The above 3 graphics are on different scales, so in order to make things easiest to understand I put everything on the same grid.

For the first case there is neither deadzone nor hysteresis, there is only an on-off control, whereas in the other graphs, there is respectively a deadband of ~1.7 at the 2nd graph, and a hysteresis/deadband of ~ 0.25/0,5 at the 3rd graph:



There is a range of input values for which no control is made, which is marked as yellow, whereas either the values marked as green and as red are both the negative feedback control which attempt to turn output back to the desired setpoint.

Here, there is a view of how control signal reacts to each range of the input, with actual values, according to the above picture: