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Questions tagged [optimal-control]

Optimal control theory, an extension of the calculus of variations, is a mathematical optimization method for deriving control policies. (Def: http://en.m.wikipedia.org/wiki/Optimal_control)

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Equivalent formulations of stochastic HJB equation

I have some trouble understanding stochastic HJB equations. There are basically two forms of this equation that I have encountered in books, lecture notes etc... (one-dimensional case) 1) $rv(x)=\pi (...
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stability of a matrix in control theory

let $\dot x=Ax$ and $S$ be an orthogonal basis of matrix $A$ i.e. $AS=0$ and let $S_\perp$ be the orthonormal complement of $S$. Is $S_{\perp}^T A S_\perp$ an stable matrix?
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How can I add find the gain from root locus and poles?

I try to find the P-gain from a root locus plot where I know the poles. Assume that we got a reference model: $$G(s) = \frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2 }$$ Where $\zeta$ and $\...
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Injectivity trajectory to set singular control to zero

Consider a control system of the form $$ \dot x(t) = X(x(t)) + u(t)\, Y(x(t)) \qquad \qquad (*) $$ where $X,Y$ are two smooth vector fields, and $u$ is the (bounded measurable) control function. ...
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Optimal stopping time for coin toss with unkown bias

I am working on a question that involves uncertainty and decision making, but I realized I am not making progress for a long time. That is why I formulated a more basic problem in the hope that I can ...
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Reference: control theory

I'm looking for suggestions on books or reviews on control theory, if possible written in a fairly modern language and not excessively technical on the math side. In particular, I would need the ...
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1answer
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Stability proof of nominal MPC with terminal cost and constraint

While going trough these slides, I wasn't able to make sense of the following on slide 32: (if only providing the url to the slides is not ok I will edit the question, but doing it like that saves a ...
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Finding the optimal solution of a specific parametric performance index with constraints

Consider the following performance index: $$J=\cfrac{1}{2}u_1^2+\cfrac{1}{2}u_2^2+\cfrac{1}{2}u_3^2+p_1\cdot u_1+p_2\cdot u_2+p_3\cdot u_3$$ Suppose $u_1$, $u_2$ and $u_3$ are the design variables and ...
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$H_\infty$ norm convergence (control systems)

So I have a question about proving the convergence (or rather a bound) of an optimization problem. I want to minimize the following function: $$\gamma := \left\|\frac{Q[A-B(x)C]}{\Re \{A \}} \right\|...
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1answer
37 views

Pontryagin Principle

Is there any reference from which I can clearly understand The Pontryagin Maximum Principle (with some clear examples). I need it to apply to dynamical systems (differential equations) and P.D.E (...
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Role of the weight matrix $M$ in $x^T M u$ in the LQR cost function

I wonder what the role of the weight matrix $M$ is in the performance index $$J = \int_0^{t_f}{\left( x^T Q x + u^T R u + x^T M u \right) \mathrm d t}$$ for an optimal control problem where $$\dot ...
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solving an optimal stopping problem

I am currently going through problems in Oksendal's intro SDE and stuck with this problem. I was wondering if I could get some help with it. I would sincerely appreciate if you would express out all ...
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Can I build an adaptive controller by using an ODE solver and a 3D graphics engine? [closed]

Let's assume that you're using a 3D graphics engine with built in physics. You create a inverted pendelum in a 3D designing software, e.g Blender, and then import the model into your 3D grapics engine ...
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1answer
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Calculus of variations with inverse of derivative composited within?

Suppose $s \in S \subset \mathbb{R}^+$ with c.d.f. $F(s)$. A real-valued function $\beta(s) \leq s$ is determined by a first order condition $\gamma'(s - \beta(s)) = g(F(s)) \in \mathbb{R}$, where $\...
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What's wrong with this robust control scheme?

I'm learning how to control a double integrator with $H_\infty$. my model is simply $ \dot{r} = v $ $ \dot{v} = F/m $ $ r(t_0) = 0$ m, $v(t_0) = 0 $ m/s, $m = 1000 $ kg so I want to be able to ...
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Control invariant set for not pointwise-in-time constraints

Given is a system of the form $$ x_{k+1} = Ax_k+Bu_k, \ k\geq 0 $$ with $x_0$ known, $x_k \in \mathbb{R}^n,u_k \in \mathbb{R}^m$ and $A,B$ of appropriate dimensions. Let $u = \begin{bmatrix}u_0 \\ \...
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Saturation limit compared to constrained limit

I have a simple question. What's the difference in behaviour between saturation limit and constrained limit in control theory? We say that we got this objective function: $$J_{min} = \frac{1}{2}x^...
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1answer
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How can I handle the delays in Generalized/Model Predictive Control?

I trying to handle delays in a model who is poorly damped but I haveing som issues to estimate its parameters due to the delay. Assume that we got a state space model, which is poorly damped: $$x(k+...
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What's the idea behind having internal integration in predictive control?

According to lots of books about predictive control, they recommend to having internal integration inside the model. For example if we have a state space model: $$x(k+1) = Ax(k) + Bu(k) \\ y(k) = Cx(...
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Create a Kalman filter from ARMAX model?

Assume that I have a ARMAX model: $$A(z)y(t) = B(z)u(t) + C(z)e(t)$$ I going to use the Algebraic Riccati Equation(ARE) to find the LQR control law $L$ by selecting the weighting matrices $Q$ and $R$...
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What's the difference between Generalized Predictive Control and Model Predictive Control?

As I know, the Generalized Predictive Control(GPC) is older than Model Predictive Control(MPC). But what is the real difference between them? I know that GPC contains some kind of system ...
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1answer
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Formalizing a Parameter Selection Problem in Machine Learning

I have a simple problem, I have an array (say of length 300), which gives me the fraction of importance of some value. I plot it and see that the value becomes flat after some index. So, I select ...
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tracking controller with fixed control bandwidth in h infinity framework

I want to synthesize an $H_\infty$ tracking controller for a second-order system. The system is subject to noise on position, velocity, and acceleration. If we look at the typical framework with ...
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How do I choose the polynomials for a stochastic filter? - Transfer functions + Extended Least Square

I'm buildning a Mimimum Variance Controller(MVC) but I having som trouble to select the stochastic filter. First of all! To build a MVC, you need a ARMAX model, in other words polynomial who look ...
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What's the applications of Minimum Variance Controller?

I going to show how to create a Minimum Variance Controller(MVC) and then ask what's the applications of MVC. First! Let's say that we have a stochastic transfer function model, ARMAX in other words. ...
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How can I choose the disturbance model if I know the plant and controller - Transfer functions

I going to select the disturbance models $C_f$ and $H$. I know my plant $P$ and the controller $C_b$. I also know that the disturbance $d$ is step formed. The noise $v$ is $v = 0$. Question: How ...
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Integral action or correction factor on disturbance?

I wonder what's the difference between having a integral action or correction factor when it comes to disturbances? Ofc I know how to apply then, the reason for this question is: What's suits best ...
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2answers
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How do I find a controller for non-minimum phase systems?

Assume that we have a transer function $G(s) = \frac{B}{A}$ which has stable poles, but unstable zeros. We use the controller $Q(s) = \frac{A}{B} = G^{-1}(s)$ and we want that the loop transfer ...
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How do I further constrain the Hamilton-Jacobi-Bellman equation to find the optimal control?

I am attempting to find an optimal feedback control using the HJB equation. I am trying to stabilize an n-dimensional state vector $x$ using a scalar control $u$ as follows: $$\dot{x} = Ax+uBx$$ ...
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1answer
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How do I place the poles and zeros form a disired system? Adaptive control

If I have a transfer function of a system $G(s)$ $$G(s) = \frac{4 - 2s}{4 + 0.8s + s^2}$$ $G(s)$ has the poles and zeros and is a stable system. And the step answer look like. It has a delay as you ...
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Numerical methods for minimum time optimal problems

I have the next optimal problem and I want to make your numerical approximation. Reviewing some references, it is mentioned that numerical methods must also be used to solve the dynamic equation and ...
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What's the difference between non-minimum phase systems and minimum phase systems?

I wonder if you can explain what's the difference between non-minimum phase systems and minimum phase systems? How can I recognize them in bode/time plots? Is this a minimum phase system? $$G(s) = \...
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Optimal control problem (constant magnitude acceleration)

A particle in $\mathbb R^2$ begins at initial position $(x_0, y_0)$ and velocity $(u_0, v_0)$. It must eventually reach a target position $(x_1, y_1)$ and velocity $(u_1, v_1)$. The acceleration of ...
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Time-optimal control of a car

I'm having trouble with the following problem: $$\begin{array}{ll} \text{minimize} & J := \displaystyle\int_{t_0}^{t_f} 1 \,\mathrm{d}t\\ \text{subject to} & \dot{v}(t)=-9.8\sin(\theta)+u(t)-\...
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What's the point of creating discrete control laws for analog processes?

Assume that we have a state space model of a real system e.g mass-spring system. $$\dot x = Ax + Bu$$ Then we want to implement this in a micro controller. The controller has a sampling rate of $h = ...
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What is the minimum time from point A to point B?

am working a bit on the theory of optimal control, and I have had a couple of doubts about how I should choose the control variable to minimize travel time. Consider the control problem to reduce the ...
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Redesigning MPC augmented state for integrating action

In model predictive control for a system $$ \begin{cases} x_m(k+1)=A_m x_m(k)+B_m u(k)+\xi_k\\ y_m (k)=C_m x_m(k)+\eta(k) \end{cases} $$ where $u$ is the manipulated variable (dimension $y$ is the ...
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Maximizing expected reward at final time via dynamic programming

Consider a state $x_t$ that probabilistically evolves over time according to a controlled Markov chain, i.e., according to known probabilities $$\mathbb P(x_{t+1}=x' \,|\, x_t=x,a_t=a)$$ where $...
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How to obtain a relation between the cost and the payoff in optimal control problems?

I have an optimal control problem to maximize the function $J =\int_0^1 x(t)-\alpha u^2(t) dt$ subjects to the system $dx(t)/dt = f(x(t),u(t),t)$ and the initial/final states. The system $dx(t)/dt$ ...
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What's the point of having a reference model in Model Reference Adaptive Control?

The MRAC(or called MRAS where S = 'System') controller is called a adaptive controller. I don't know why, because it have no system identification process loop. But what's the point to having a ...
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Optimal control: what do I do if dH/du doesn't depend on u?

I'm solving a simple optimal problem. My objective function is: $$J(u) = \int_{t1}^{t2}(u_{1} + u_{2})dt$$ and other equations depend on $u_{1}$ and $u_{2}$ linearly. So when I formed Hamiltonian ...
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Same LQR feedback but different cost weights

I'm searching for a reference for a result in Optimal Control. Some preliminaries: The LQR feedback $u_t$ is given by solving \begin{align} &\min_{u_t} && \mathbb{E}\left[x_T^\top ...
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optimal control with a constant choice

I am trying to solve an optimal control problem. On top of state and control variables, the objective function depends on a constant scalar that I can choose. I have thought about defining the scalar ...
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Augmented nonlinear state space model for nonlinear model predictive control?

Assume that we have a discrete state space model: $$x(k+1) = Ax(k) + Bu(k)\\ y(k) = Cx(k) + Du(k)$$ And we want to use optimization to minimize this cost function. $$J =\sum_{k=0}^{n}(x_k^TQx_k + ...
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Pontryagin principle, Optimal control or Numerical scheme ? logical constraint?

I have the following optimal control problem : $ \textit{ Minimize } \qquad J(u,x,T) =\displaystyle \int_0^T \Big[ u_1(t)\log\frac{u_1(t)}{ x_1(t)x_2(t)} - u_1(t) +x_1(t)x_2(t) \qquad \qquad \...
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1answer
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Avoid equality constraints - Only lower bound and upper bound - Quadratic Programmering

The quadratic programming objective function for MATLAB and Octave is: $$J_{min} = \frac{1}{2}x^THx + x^Tq$$ and the constraints are: $$lb <= x <= ub$$ $$Ax = b$$ In this case, I want to use ...
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How does terminal constraint lead to degeneracy?

In the paper: TøNdel, P., Johansen, T. A., & Bemporad, A. (2003). An algorithm for multi-parametric quadratic programming and explicit MPC solutions. Automatica, 39(3), 489-497. I have seen ...
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1answer
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Derivative of a Summation in Optimal Control Problem

I am attempting to solve for the costate on an optimal control problem and am having difficulties solving the derivative $\frac{dL}{dx}$. Due to the fact that L contains a summation of x terms. x and ...
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1answer
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Sliding Mode Control for fluid mechanical system - How to find the control law?

Assume that we have a water tank system: $$A \dot h = Q_\text{in} - Q_\text{out} = Q_\text{in} - a\sqrt{2gh} $$ Where $a$ is the opening area in the bottom of the water tank and $\sqrt{2gh}$ is the ...
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Why the plant in MPC is assumed to be strictly proper?

The model of plant in Model Predictive Control (MPC) is assumed to be strictly proper (Wang 2009: page 4). $$ \begin{aligned} & x_m(k+1)= A_m x_m(k)+B_mu(k)\\ & y(k)=C_m x_m(k) \end{aligned} $...