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Questions tagged [stability]

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Horizontal tip extensions and C-wing design for stability of tailless drone

I am a robotics student and new to aeronautics. My task for a project is to build a flying wing drone with limited wingspan (<1m), 25cm chord at wing root, total load of 2.5kg (1.5kg empty) and ...
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What are the necessary qualitative criteria for the existence of limit cycles

The literature on the existence of limit cycles is replete with complex and abstract mathematical analysis. Or for specific systems of specific structure, specific mathematical criteria that determine ...
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58 views

Control systems, Nyquist plot and root locus

I need help in understanding the connection between Nyquist plot and root locus plot. Let's say I have a Nyquist plot, what can I infer about the root locus plot? and vise versa. Given the root ...
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34 views

Solar panel actuator control

I'm looking to design a system that can control a solar panel through an electrical actuator for a range of motion of -45 to +45 degrees for maximum solar exposure. The panel will be mounted on a 10 ...
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Is the following system considered to be stable or unstable?

For a plant G(s), the transfer function is given by: $$G(s) = \frac{(10s+50)}{s(s^2+20s+2500)}$$ the PID parmeters are given by: $$K_p=5135$$ $$K_i=6.731$$ $$K_d=0.01475$$ $$T_f=8.57e-05$$ The ...
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Finding stability of open loop system connected to closed loop system

I have a simple cruise control closed-loop system with negative feedback and have no problem using the Nyquist stability criterion to find its stability. However, I have another function that ...
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Vehicle yawing during straight line acceleration

My FSAE vehicle is yawing when we are doing our acceleration test. The vehicle is moving like a fishtail at the start of the run. But it stops after some distance and the vehicle stabilises itself ...
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32 views

Can I replace terminal weight with an even stricter matrix yet ensuring stability?

Terminal Penalty is used to ensure stability of Model Predictive Control (MPC). where the initial cost function is $$J(u)=\Sigma_{i=1}^{\infty}[x(k+i)^TQx(k+i)+u(k+i−1)^TRu(k+i−1)]$$ it is ...
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Maximum slope of the road for a car pulling a trailer

I have a five meter long, 2.40 meter wide, 200 kg portable catamaran I've built at home. To transport, I bought a semi-finished trailer, just the running chassis; and built the upper structure, namely ...
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2answers
64 views

How to solve system's general stability from transfer function?

I have a homework which should solve by me. My problem is questions are really simple or should I think outside of the box? Like, bode diagram, nyquist or etc.? And, are my answers correct? Thanks. ...
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PID control for UAV [closed]

I'm working on a deltawing model airplane where I want to implement a PID controller to stabilize the pitch, roll and yaw (which are only controlled by two elevons). However, I don't know too much ...
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Exponential stability under a global coordinate transformation

Consider a system of the form \begin{equation} \Sigma\colon\ \dot{x}=f(x), \end{equation} where $x\in \mathbb{R}^n$ and $f\colon \mathbb{R}^n\to \mathbb{R}^n$ is a sufficiently smooth function ...
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Eliminating lateral motion in a pair of 4-bar mechanisms

As my first serious mechanical engineering project, I've built a wall-mounted folding table using of a pair of 4-bar mechanisms (WIP, ignore the wall mounts): I'm using fisheye bar ends with ...
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1answer
356 views

Control Systems: Why is this system unstable?

I am currently doing a control systems course and I was lead to believe that if a pole lies on the imaginary axis in the s-plane (i.e s=0), then the system was marginally/critically stable. However, ...
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461 views

Transfer Function of Spring-Damper System

Given the spring-damper system below where $x_i$, $x_i$, and $y_i$ are position values, how do I find the transfer function $\frac{X_o(s)}{X_i(s)}$? Wouldn't it require mass? I tried neglecting the ...
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52 views

Vertical Linear Actuator Sway Movement

I'm designing something with a vertical linear actuator. It is a quite large actuator lifting a load. I'm anticipating sway from the actuator as it moves up and down so I'm creating a support ...
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What will be the effect of torque and wheel diameter on the stability of a robot?

I'm building a self balancing robot and would like to know how the wheel diameter and the torque provided by DC motors, would affect the overall stability and response of the robot. The balancing bot ...
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1answer
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Passivity in automatic control (Linear and nonlinear control)

The definition of passivity for control systems is: $\langle y,u \rangle _T \geq 0 \: \: \: \forall T >0 \: \: \: \forall u$. Considering signals $u,y :[0,T] \rightarrow R^m$. As I understand it, ...
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47 views

stability/controllability of a finite time linear quadratic regulator

If I have a linear quadratic regulator (quadratic objective function with linear dynamics) and use an open loop control - are there stability/controllability requirements on the system? I know that ...
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Is a chair with N+1 wheels ever less stable than a chair with N wheels?

My workplace has a policy to provide standing desks upon request, but no policy to provide chairs of matching height. (I work for the government...) We can buy our own, or build our own. However ...
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226 views

Controller design with pole placement method with given damping and settling time

I was given the following equations and asked to design a controller for $u=-Kx$ using a pole placement method with the closed loop system having the damping and settling time $T_s$ given. Am I ...
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1answer
165 views

Equilibrium of rigid bodies

I wanted to evaluate the safety of a walking aid device (walker). For example, if the way it is constructed and whenever I handle it, there are no risk of rotation, around its center of mass, turning ...
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A stable transfer function which diverges?

This question might sound stupid as I'm more of a software guy and never really had to do control engineering (besides the 101 classes). So I have a second order system I could approximate, with the ...