Seth on SimulinkMay 22nd, 2009Robotic Arm Models and Repairing HubbleAs you may know, Space Shuttle Atlantis is about to return this weekend from man’s last visit to the Hubble Telescope. Those astronauts took some major risks to repair our favorite and most famous scientific instrument. One of the tools they used during space walks is the robotic manipulator from the Canadian Space Agency (the robotic arm).
Image Credit: NASA I have never had a chance to operate a CSA robotic arm, but my colleague Guy Rouleau has! Guy told me about a Simulink S-function he created to help in controlling a robotic arm in Simulink. Changing the color of blocks during simulationBy Guy Rouleau
I have many good memories from my internship at the Canadian Space Agency when I was studying for my bachelor degree. During this internship, I was developing control logic for a robotic arm. Simulink was used to develop the controllers and as a user interface to command the robot.
When driving a robotic arm simulation using a joystick, it is not always easy to visualize if you are close to a joint limit or a singularity. It is possible to display the state values in the model, but hard to know if you are about to lock out control of the arm. To help the person driving the robot, we though it might be cool to make blocks in the Simulink diagram turn red when close to a limit. This is what it looks like in action with the SimMechanics mech_robot_vr.mdl model.
Here is a quick explanation of how to changing the color of a block with a simple Level 2 M-file S-Function. As a template, I suggest starting with the demo M-file msfcn_times_two.m. In your MATLAB installation, you can open this file using the following command:
Only a few modifications are required to make the file change the color of a block based on the value of the signal connected to the s-function. To begin, save the file as ChangeColor.m for this example. At the minimum, you need to modify the code of the Output section. To start, I created a model named “Test” where we will change the color of the block named “Display”
The simplest implementation can look at the input value, and then use set_param to modify the block BackgroundColor:
In the above code, the color of the block “Test/Display” is set to green or red depending if the input is larger or smaller than zero. In order to make the code reusable, I may want to determine automatically which block is connected to the S-Function. We can also add a parameter to the block to set the value at which the color switches. In that case, we add these lines to the setup function:
Notice that the handle to the destination block is stored in the “UserData” of the S-function. UserData is often useful for storing any data you need to persist with the S-function, but doesn’t fit the definition of a continuous or discrete state. The output function now looks like:
Finally, if you want the block to return to white at the end of the simulation, you can add these lines to the terminate function:
You can find this example in my File Exchange Submission: Changing the color of a block while the simulation runs. Now it is your turn Do you work on a robotic arm or on the Hubble? Have you used an S-function to customize what Simulink looks like? Share your experience and leave a comment here. 9 Responses to “Robotic Arm Models and Repairing Hubble”Leave a Reply |
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Good Evening,
I’m glad to see you webpage,it gives me many ideas to work and study of robotics.
Thanking You.
hi.!im currently into the studying a robotic arm and possibly simulating one by controlling it by a joy stick..could you possibly send me some infos on your program the casing of your arm etc..tnx
@Syed Murtuza Hussain - Happy to provide some inspiration.
@Rienzi Mosqueda - The example models I would share with you are part of the demos in SimMechanics. They all depend on the SimMechanics product, so they would not work unless you have a license. Some of the product demos are indexed on mathworks.com here:
http://www.mathworks.com/products/simmechanics/demos.html
clc;
clear all;
% To Open a new model file the Existing Model
% new_system(’Chaining_Diagram’,'Model’)
% To Open the Existing Model
open_system(’Chaining_Diagram’)
Pos = [115, 88, 155, 122];
for i = 1:3
% To add a block to the model
h = add_block(’simulink/Ports & Subsystems/Subsystem’, ‘Chaining_Diagram/Subsystem’, ‘MakeNameUnique’, ‘on’);
if i == 1
add_block(’simulink/Sources/In1′,’Chaining_Diagram/Subsystem/In1′, ‘MakeNameUnique’, ‘on’);
add_block(’simulink/Sinks/Out1′, ‘Chaining_Diagram/Subsystem/In1′, ‘MakeNameUnique’, ‘on’);
else
path = strcat(’Chaining_Diagram/Subsystem’,num2str(i-1),’/In1′);
add_block(’simulink/Sources/In1′, path, ‘MakeNameUnique’, ‘on’);
add_block(’simulink/Sinks/Out1′, path, ‘MakeNameUnique’, ‘on’);
end
% To set the Dimension of the block
set_param(h, ‘Position’, Pos)
set_param(h, ‘ShowPortLabels’,'off’)
BlkName = strcat(’disp(’,num2str(i),’)');
set_param(h, ‘MaskDisplay’,BlkName)
set_param(h, ‘ShowName’,'off’)
set_param(h, ‘Mask’,'on’)
Pos = Pos + [0, 100, 0, 100];
end
add_line(’Chaining_Diagram’,'Subsystem/1′,’Subsystem2/2′,’autorouting’,'on’)
add_line(’Chaining_Diagram’,'Subsystem/2′,’Subsystem1/1′,’autorouting’,'on’)
add_line(’Chaining_Diagram’,'Subsystem1/1′,’Subsystem2/1′,’autorouting’,'on’)
add_line(’Chaining_Diagram’,'Subsystem1/2′,’Subsystem/2′,’autorouting’,'on’)
add_line(’Chaining_Diagram’,'Subsystem2/1′,’Subsystem/1′,’autorouting’,'on’)
add_line(’Chaining_Diagram’,'Subsystem2/2′,’Subsystem1/2′,’autorouting’,'on’)
% To save the open System
save_system(’Chaining_Diagram’)
%*************************************************
please help me to avoid overlapping of lines when this piece of code Executes.
THanks in advance
I am an Mphil Student at the University of the West Indies, St. Augustine, Trinidad & Tobago - Faculty of Mathematics and Computer Science. Presently my studies are in emotional recognition in artificial systems using Matlab Simulink as a simulation tool and PSO Models and how it can be applied to Emotion-Oriented eCommerce Systems.
I have been researching extensively on existing Simulink Control models which are able to simulate the emotions of a user. Such a Model should possess a stated emotional model. However, at this juncture my research is proving futile.
I would like to know if there are actually any Simulink Control Models created in Matlab that can simulate the emotion of a customer or user and how can they be accessed. I do not want to reinvent the wheel if such a project has already been done. The aim is to use an existing simulation to support my findings. This system will be well referenced in the final production of my thesis.
Do you therfore have an emotional model simulated in Simulink and PSO? If this is available for review, can you make the Model available for further analysis?
Your help and suggestions would be greatly appreciated.
@Simone Leon - while I have talked to people about modeling financial systems and biological systems, I have not seen any “emotional models.” I suggest you reach out to a larger community (like comp.soft-sys.matlab) to find an answer. If you have a clear idea of what states your are modeling, and the conditions that lead to transitions between those states, it will be easily expressed in a Stateflow chart.
Are there then any matlab/simulink programs used for recognizing and simulating happy,sad,joy,nervousness,disgust etc….
To be a little more detailed, are there then any matlab/simulink stateflow diagrams or programs used for recognizing and simulating happy,sad,joy,nervousness,disgust etc…. I now there are emotion and face recognition programs in matlab. However, I have not seen any stateflows diagrams that would represent such a simulation. Are there any?