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Bill Tubbs


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66 total contributions since 2020

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Answered
How to deal with Extended Kalman Filter in Simulink when my state transition function is given in continuous time form?
Check out the examples in the documentation here: https://www.mathworks.com/help/control/ref/extendedkalmanfilter.html The exa...

12 days ago | 0

Answered
Simulink: There is no solver registered as 14.
I don't know exactly what caused this error but I found I could run the msfcn_limintm.m example from the S-functions in the docu...

13 days ago | 0

Answered
How are structs handled when passed to a function?
Seems that MATLAB makes a complete copy of a struct when it is passed to a function if any element is changed by the function (s...

14 days ago | 0

Question


Unable to detect datetime or duration data using readtimetable with a seconds index
Here is a toy example of my problem: % Create a timetable with a seconds index data = timetable(seconds(1:3)', randn(3,1), ran...

1 month ago | 1 answer | 0

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answer

Answered
Find the First element that satisfies a condition
If you only want to find the locations in A where the condition is true and then index those values you can use find: >> elemen...

1 month ago | 0

Answered
What is the 'MeasurementFcn1Inputs' input on the Extended Kalman Filter Simulink block?
I found the problem. I was using the same function (robot_outputs) for the NLMPC and the EKF: function y = robot_outputs(x,u) ...

1 month ago | 0

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Question


What is the 'MeasurementFcn1Inputs' input on the Extended Kalman Filter Simulink block?
I'm trying to implement an Extended Kalman Filter Simulink block similar to the example shown for the inverted pendulum here whi...

1 month ago | 1 answer | 0

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answer

Answered
Get a subset of columns from a timeseries object as a timeseries
Here is my answer to illustrates the timetables solution proposed by @dpb in the comments above. u = timetable(seconds(t),u1,u2...

1 month ago | 0

Question


Get a subset of columns from a timeseries object as a timeseries
I have a timeseries containing data for 4 variables: Ts = 0.2; nT = 50; t = Ts*(0:nT-1)'; u1 = 50*idinput(nT); u2 = 50*idinp...

1 month ago | 2 answers | 0

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answers

Question


How to insert the 'double R' symbol in LiveScript (space of real numbers)
Anyone know how to get this symbol in the LiveScript equation editor? MS Equation editor equivalent: \doubleR Latex: $\mat...

2 months ago | 1 answer | 0

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answer

Question


Is it possible to solve multiple linear systems of equations in parallel with one matrix operation?
I'm wondering if there's a way to do the following calculations in one go (i.e. without the for loop). V = nan([na nv]); for i...

2 months ago | 0 answers | 0

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answers

Question


How to replace elements of a cell array using a containers.Map
I have a cell array of VariableNames that Matlab created when reading a csv file. I want to change them to my own choice of nam...

4 months ago | 2 answers | 0

2

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Answered
Solve equation that has a complex subexpression
I just discovered that you can also solve this numerically with vpasolve: syms s omega G(s) assume(omega > 0) G(s) = 10/(s*(1...

6 months ago | 0

Question


How to find the 'troughs' using peak finder in Simulink Scope
I've been using the Peak Finder Measurements tool in the Simulink scope output to find the peak of the system responses. But if...

6 months ago | 1 answer | 0

1

answer

Answered
How to check if two transfer functions are the same?
Based on comments from Paul above I offer these functions as a solution: function c = is_equal_tf(G1,G2) c = almost_zero_s...

6 months ago | 0

Question


Basic math operations on contents of a cell array
Is there any reason why basic math operations don't work with cell arrays? Seems to me it would extremely useful and efficient ...

6 months ago | 2 answers | 0

2

answers

Question


Best way to resample the output of a Simulink simulation with variable time step into a signal with a fixed sample time
I have a simulation model that runs with a variable timestep: (I don't want to change this) For the purpose of system identi...

7 months ago | 1 answer | 0

1

answer

Question


How to turn off text interpreter when plotting timeseries objects
I am plotting timeseries objects using plot. My variable names include underscores (e.g. 'ABC_DEF') and I do not want these int...

7 months ago | 2 answers | 0

2

answers

Question


Evaluate function over a mesh grid (without for loops)
Is there a way to evaluate a function that takes an [x, y] vector as input over a grid of points? Here is the function I want t...

7 months ago | 2 answers | 0

2

answers

Answered
Why do I get the warning "MATLAB:dispatcher:InexactCaseMatch Cannot find an exact (case-sensitive) match for 'startup'" on MATLAB startup?
For me the problem started after I added a path to a module that I am using for a course. The scripts in this module are launch...

8 months ago | 0

Answered
Why are symbolic expressions being rounded?
Mathworks technical support have diagnosed the problem. Don't know what caused it originally but the 'FloatingPointOutput' sett...

9 months ago | 0

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Question


Why are symbolic expressions being rounded?
I'm deriving some expressions symbolically and then substituting values and computing the results and I only recently noticed th...

9 months ago | 2 answers | 0

2

answers

Answered
Trying to set parameter values in a Simulink model using a parameter structure
I gave up on trying to figure out the ParameterStructure method and ended up doing it this way which I assume is the standard wa...

9 months ago | 0

Question


How to get subscripts in the legend of a Nichols plot?
How do I put subscripts in a Nichols plot legend? This works fine in a normal plot: figure plot([0 1],[3 4]); hold on plot([...

9 months ago | 1 answer | 0

1

answer

Question


Trying to set parameter values in a Simulink model using a parameter structure
I'm following the docmentation here in an attempt to set up a Simulink model so I can apply a set of parameter values to it befo...

9 months ago | 1 answer | 0

1

answer

Answered
I get Error: Invalid expression. Check for missing or extra characters. when commenting out lines in a multi-line statement
Here is one solution but it's hardly very convenient and contrary to commenting-out in other languages: y = ... 1 + ... ...%2...

9 months ago | 0

Question


I get Error: Invalid expression. Check for missing or extra characters. when commenting out lines in a multi-line statement
It seems you can't comment-out entire lines in MATLAB within a multi-line statement. Or am I doing it wrong. A few examples be...

9 months ago | 2 answers | 0

2

answers

Answered
How to implement an RST controller in Simulink?
After some further diagnosis, I think I have solved the problem. The default setting of the Discrete-Time Integrator block is '...

9 months ago | 0

Question


How to implement an RST controller in Simulink?
Every time I search for help on this I am taken to the following page: RST Controller But I don't have access to the Simscape ...

9 months ago | 1 answer | 0

1

answer

Answered
How to simulate a discrete linear system model with a user-specified disturbance signal?
I found the answer in the documentation: opt = simOptions('AddNoise',true,'NoiseData',e); Turns out I was looking at the wrong...

9 months ago | 0

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