# Questions tagged [stability]

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### Do transfer function changed in vertically placed spring damper system when an additional mass is added

Title: Calculating the Transfer Function and Displacement for a Spring-Damper System with Additional Mass I am working on a problem involving a spring-damper system, and I need help with calculating ...
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### Basic questions about power grid stability with variable loads and sources

I am curious about integration of renewable energy in electricity grids. I am a mechanical engineer and understand energy and power but I have little knowledge about electricity. I will be thankful if ...
• 148
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### Stability properties of controllers with independent control laws applied in underactuated systems

I am interested in designing a GNC controller for a 3DOF underactuated vehicle that follows a path in 2D space. The two available control inputs are the thrust force in the surge direction and a ...
1 vote
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### How do I find the minimum/maximum stable value of scalar gain for a closed loop transfer function?

I have the following transfer function: $$G(s) = \frac{s + 8}{s^2 − 2s − 3}$$ This function is placed in series with a static gain $k$ and unity feedback. In this case I'm looking for the minimum ...
40 views

### Who takes care of structural health monitoring of civil structures?

There are numerous studies about the possibility of structural health monitoring (SHM) of tall structures, like bridges, skyscrapers, water towers, wind turbines, where, for example, inclination or ...
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### How to determine the stability of an aerodynamic shape in ANSYS Fluent

I have the aerodynamic outer mold line file of a drone. The first task of the school project is to verify that the drone is stable. First, I used the 2021R2 version of ANSYS Fluent to try to find the ...
• 143
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### Definition of BIBO stability of a nonlinear system

I am studying an electric motor whose state-space equations are nonlinear. I am trying to control the system through a closed loop and I would like to verify the BIBO stability. For linear systems, ...
• 101
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### If there is a instability issue inside the control loop, and the control system starts oscillating, what will be the oscillation frequency?

I have a closed loop controller to control the vehicle on the centerline with a bandwidth of 2 rad/s, and I saw the vehicle keeps oscillating around the centerline in a sinusoid whose period is around ...
• 57
1 vote
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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 ...
• 141
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### Describe the magnitude of a force using real-life comparisons instead of numbers

I already asked this on physics.se, I got a suggestion to ask here, but the question became too old to migrate before I decided to do it. I did also receive an answer, and I am grateful for it but ...
• 101
1 vote
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### Understanding the RMS noise for a given bandwidth

I would like to ask a technical question regarding the current source Keithley Series 2400 Model 2450. I am looking for a high stability current source capable of feeding some Hall probes with a ...
• 11
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### Determining stability of a current souce from the datasheet. How to?

Is there any way to calculate the stability of an instrument such as current sources and digital voltmeters from their datasheet? Let me provide one example. My application requires stable current ...
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1 vote
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### How do I determine the pitch/roll stability of a buoy?

I am designing a loosely-moored spar buoy (large height relative to width), and the equipment on top needs to remain as vertical as possible while floating in the sea, within limitations of buoy cost, ...
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### Did I get the correct result? Block reduction problem

After solving I got $$T(s) = \frac{s^{2}+3s+3}{(s+1)(s+2)}$$ and for the stability of the system I got: $$s_1 = -1$$ $$s_2 = -2$$ So, is the system stable?