# Questions tagged [control-engineering]

Questions about the models and theories of control engineering and the application of control theory to design systems with desired behaviors.

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### How to tune a PID controller when plant's step response looks like a ramp?

The system is a boat and I want to specify a yaw angle and the PID controller would operate the rudder of the boat in order to reach the desired yaw angle. So, the step response of the plant (boat) ...
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### What is residual oscillation and critically damped oscillation in the context of a controller's performance?

What do these terminology "residual oscillation" and "critically damped oscillation" mean when evaluate a controller's performance? How are they related to the stability of the ...
20 views

### How to determine time constant/cutoff frequency of the filters in the controlled loop

I was told to be careful to use filters in the control loops as it will add extra time delays in the system and degrade the system dynamic response, but I also saw there are lots of filters in ...
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### How could I verify the stability of a real system with non-linearities?

For a closed loop system, I could do the stability margin analysis using linear method like bode diagram, but in reality there are non-linear elements in the system like saturation/rate limits inside ...
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### Control System Response

How does one find the zeta value or the frequency of an over damped response curve. I am used to determining things by using the log-decrement equation. Does that apply here even though there is no ...
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### Could someone explain how a compensator shifts the root locus?

I'm reading a root-locus course note from MIT. However, I can't understand this part: How does adding a compensator with a pole at origin remove the plant pole on the right half-plane into the left ...
46 views

### Drawing nyquist diagram by hand for a system with time delay

how can I draw the Nyquist diagram of Kexp(-Ts)/(s*(s^2+s+a) by hand for different a and K values and examine the stability of the system depending on T value? I drew for the case with no time delay ...
28 views

### Sliding-mode control is a model-based technique?

The sliding mode control can be considered a model-based control? In my opinion yes since takes the information of the mathematical model of the system to be controlled handling with possible ...
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### Controls System experiment

We performed an experiment in which we turned a bicycle on its side and placed a piece of green tap on one of the spokes. We spun the wheel and recorded the wheel spinning until it came to a complete ...
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### Can I design/tune the outer loop controller without knowing the details of the inner loop controller?

In cascade PID control loops as below, can I make an assumption that the inner loop will respond much faster than the outer loop, hence I could simplify U1_CMD as U1 and I could design/tune the gains ...
23 views

### What is the original paper using Extended Kalman Filter for joint state and parameter estimation [closed]

The title says it all. I would like to know which was the first paper to apply the Extended Kalman Filter to jointly estimate the state plus some parameter of the system. (by extending the system ...
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### Stability from Gain and Phase Margin

I know that a system with positive gain and phase margin is a stable system. And the one with a negative gain and phase margin is unstable. What will a system with negative phase margin and positive ...
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### Phase margin by definition

I'm reading about Gain Margin and Phase Margin in a book and having trouble understanding why they calculate the Phase margin like this: <G(Wcrossover) - (-180) = PM Why not: <G(Wcrossover) - (...
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### Optimizing error for PID based control of Line Following Robot

I am working to find the optimal PID gains of my line following robot. To do this, I need to optimize any performance index dependent on the error (a typical example is the integral absolute error). ...
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### Lyaponuv stability condition of linear systems for homogenous P in V(x) = x^T P x

I am currently learning about using Lyaponuv functions to find Linear Matrix Inequalities (LMIs) as conditions for stability of a linear time invariant system. i.e. $$\dot{x}(t) = Ax(t)$$ is stable ...
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### Issue with LQR Q matrix for a cart-pendulum model

I am currently trying to develop a controller using LQR for a Segway. The model that I am using is an inverted pendulum on a massless cart. I have made animations of the uncontrolled pendulum and of ...
63 views

### Dividing torque of one axle to three in varying proportions [closed]

I want to power a small mechanical monstrosity, which performs three tasks that require three separate axles. For the powering, there's a hand-operated crankshaft connected to the primary axle that ...
65 views

### What type of electrical machine component for counting time?

I am looking for the proper piece of hardware to do what I'm looking for on my current prototype machine build. I want a timer to begin counting upwards in seconds when a switch is activated, and ...
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### Demonstration of Controlability and Observability

After I studied my Control Engineering courses some years ago, although I was able to interpret the results obtained after calculating the observability and controllability, I haven't been able to ...
In short, I suppose the question boils down to: If we are asked to find the state space representation of $C(s) \cdot G(s)$, where C(s) and G(s) are both transfer functions, then do we treat them as ...