# John Petersen

### Autonomous Solutions, Inc.

Control systems engineer with PhD in EE at Autonomous Solutions and I love to ski, run and bike trails.

Professional Interests: Control systems, Localization/Navigation, Estimation, Electronic Design, Sensor Fusion

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**Content Feed**

Question

How can I determine where or if a bus is used in a simulink model?

I have a complex simulink model that has dozens of busses defined. Some busses are identical but with different names. I have f...

9 months ago | 1 answer | 0

### 1

answerQuestion

How to convert a layered structure into arrays.

I have a structure like this A.a.b.first, A.a.b.second, A.a.b.third A.c.d.first, A.c.d.second, A.c.d.third A.e.f.first, A.e.f...

10 months ago | 2 answers | 0

### 2

answersQuestion

Variable Not fully defined on some execution path error

I have some code that is inside a simulink block that gets an error when it's compiled. It says a variable is not fully defined ...

11 months ago | 1 answer | 0

### 1

answerQuestion

How do I plot the progress of fmincon to see the convergence of the approximation?

I want to see the output at each iteration of the optimization. I am solving for MPC and want to plot the entire future solution...

1 year ago | 0 answers | 0

### 0

answersDoes a single nodelocked license file support multiple matlab versions

Yes, this is possible. See https://www.mathworks.com/matlabcentral/answers/99348-is-it-possible-to-have-multiple-releases-of-...

1 year ago | 0

Error using cd Cannot CD to 7364 (Name is nonexistent or not a directory).

You are changing directories in the first for loop so that by the time you get in to the second for loop you are not starting in...

1 year ago | 0

How to keep the slider position the same after retrieving its value?

It's not a great idea to be using any globals in here. My guess is that roadA has the value of 5 and that's why slider_input =...

2 years ago | 0

Question

How do I change a configuration parameter for all simulink blocks in my model?

I recently upgraded to 2016b from 2015a and now I'm getting many warnings about units inconsistency. I don't use or care about ...

4 years ago | 0 answers | 0

### 0

answersQuestion

Can I index into a timeseries using time?

I have a timeseries and I want to index into the timeseries using time to get the data. Is there an elegant way or do you have t...

4 years ago | 1 answer | 0

### 1

answerQuestion

How do I control the size of a checkbox in a programmatic GUI?

I have a programmatic GUI and I'm trying to change the size of my checkboxes, but I can't get it to change. I've tried changing...

5 years ago | 1 answer | 0

### 1

answerQuestion

How to index every field of a structure and reassign to a structure with a single element in each field

I have a structure where every field is an array of the same length. I need to pass this structure on but only with a single ele...

5 years ago | 2 answers | 1

### 2

answersQuestion

How do I get my text to center vertically in a uicontrol textbox?

I am creating a GUI programmatically and I have a panel that I am displaying text boxes. How do I get my text boxes to display t...

5 years ago | 1 answer | 1

### 1

answerhow do I print a txt file of integers and floats?

Thank you for your input and suggestions! I have finally come up with this Ad = double(A); % cast the int to a double d...

5 years ago | 0

Question

how do I print a txt file of integers and floats?

I have tried in vain to write a text file of a mix of ints and floats. Suppose I have A = nx1 ints, and B = nx1 floats I want ...

5 years ago | 4 answers | 0

### 4

answersQuestion

How do I rename fields of a structure array?

Say I have a structure array such as A = 1x49 struct array with fields: a b c d H...

6 years ago | 6 answers | 0

### 6

answersQuestion

How do I assign the same value to every field, including nested fields of a structure?

Say I have a structure which has an unknown number of fields and each field may or may not have subfields. I want to assign a ce...

6 years ago | 1 answer | 0

### 1

answerQuestion

How do I run a script from a GUI that will run in the 'base' workspace?

I have a simulink model that uses a lot of variables from the base workspace. Now I am making a GUI that runs the model, but I w...

6 years ago | 2 answers | 1

### 2

answersQuestion

Structured Cell array assignment question

If I have something like A(1).a = {c}; A(2).a = {d}; and B(1).a = {e}; B(2).a = {f}; and want to assign ...

6 years ago | 2 answers | 0

### 2

answersQuestion

xlsread doesn't recognize file has changed

I have a .xlsx file that I read with xlsread. However, if I change the file and call it with xlsread again, it returns the old v...

6 years ago | 0 answers | 0

### 0

answersQuestion

How do I make assignments to my workspace using variable names and values in a spreadsheet?

I have an excel file that has names of structures in the top row, names of fields of those structures in the 2nd row and in the ...

6 years ago | 2 answers | 0

### 2

answersSimulink model does not "continue" after a "pause" by using set_param commands.

Your sim stops because of the pause. When you press play, it continues for one cycle and then is told to pause again in your ass...

6 years ago | 0

Question

Fill a listbox with the text of a set of enumerations

I have a listbox in a GUI that I want to populate using enumerations. My class of enumerations might be something like mye...

6 years ago | 1 answer | 0

### 1

answerProblem saving cell to txt file

The error is telling you that you can't use cells in your print function. That's because cell arrays can be different lengths, a...

6 years ago | 0

| accepted

How to use LQR and code generation?

The 'work around' is to write your own Ricatti Eq Solver.

6 years ago | 0

Question

Turn a cellarray into a single array.

I have a cell array, sig, with varying lengths of data in each cell. For example (on a simplified scale) sig = [{1}; {[2 ...

7 years ago | 2 answers | 0

### 2

answersHow to convert step varying signal into linear signal(gradual rise and fall)>

One way to do it is to sample the step varying signal at each step and then use the result or you could fit a spline or polynomi...

7 years ago | 0

Function for Script. I need to write a Function that selects the positive and negative numbers from a matrix. How to write this?

a = 0.5 - rand(3,3); %Positive numbers a(a>=0) % negative numbers a(a>0)

7 years ago | 0

Substituting a number for NaN in anonymous function

You have .*f(x) in g(x), which is still giving you a NaN

7 years ago | 1

Solving steady state Kalman riccati equation

Just write out the equations. If it's 2x2 it shouldn't be too hard. Q and R are almost always diagonal. P is symmetric, so thes...

7 years ago | 0

Extended Kalman Filter converges to wrong values (super simple model)

You have a constant dt used in the filter, but the simulation is variable step. This will cause problems with your predictor. ...

7 years ago | 0

| accepted