# Questions tagged [control-system]

A system that may be electronic circuits or even software that uses control theory (principally differential equations) to control an output by monitoring various aspects of the system under control and varying inputs all towards meeting a defined goal. Some famous examples are controlling a rockets thrust angle to ensure directional control.

824 questions
Filter by
Sorted by
Tagged with
162 views

### Nyquist stability criterion for positive feedback

it is known that the stability of a system with negative feedback may be analized through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
48 views

### Difference between Linear control theory and non linear control theory? especially topics/contents wise?

Although I know that a linear systems is the one that follows principle of superposition but I want to know what topics/contents do we study in each of both categories linear control and non linear ...
61 views

### Effect of zero coefficient in polynomial in Routh Hurwitz?

Consider this polynomial: $s^4+2s^3+3s^2+4s+5$ What happens if we have zero in place of any coefficient in our polynomial? Will that indicate that the system is unstable? Let say we have zero ...
244 views

388 views

### Can my PID controller have negative p value and positive i value for a PID logic

I am building my first PID controller. My process variable and my actuator value are inversly related, meaning if actuator value increases process variable decreases, and vice versa. So I have tried ...
910 views

### Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180Ā° is bad. If my input is a sine wave and I have negative feedback, which has a -180Ā° phase shift, the ...
156 views

### Sluggish step response of control loop

I have a question regarding the PI controller. Lets say I have an actuator via which I control some plant. The control signal at the output of the PI controller is at its maximal realizable value. So ...
65 views

### How do I calculate this inverse Laplace Transform

I have this transfer function and input, and I have to manually calculate what the systems response will be. The transfer function is: and the input is: I multiplied the two functions and used ...
58 views

### Method for selecting unique resistor values in all combinations

I do controls, and sometimes I want to monitor more dry contacts than I have digital inputs for. I'm cheap, and don't want to pay for more points, so sometimes I'll put some resistors in parallel ...
797 views

### Understanding the role of Pole zeros cancellation from the definition of stability

I have encountered the following theorem in a book. According to me, I can get an asymptotically stable system even if cancellations exist for the unstable poles. my example, Then Why does this book ...
267 views

### Tuning PID coefficients for stationary stability of brushless DC motors

I'm using a commercial off-the-shelf brushless DC motor controller. It combines a PID controller and an absolute encoder to regulate position. When my motor reaches its target state, it generates a ...