I'm planning on simulating a real world scenario in Matlab. I have an experimental setup inside a closed environment in which the humidity is controlled predominantly. I'm studying the effects of humidity on the machine and see if the output of the machine itself along with the raw material fed into the machine depends on the varying levels of humidity. Is it possible to mimic the same environment in Simulink/Simscape without any test dataset solely depending on the physical equations of the physical parameters and the machine and materials involved? As an example, i can state the working of a machine to extrude plastic resins in a closed environment where the humidity is kept constant at different levels and the efficiency of the extruder at different levels of humidity is calculated based on the experiments. Can i repeat the same in simulink/simscape by setting up the same model? My aim would be to compare the real world scenario with the matlab model. I would be grateful to get some expert opinions/help/answers inside the stackoverflow community. Thank you!
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What is the added value of simscape physical signals compared to normal simulink signals? As far as I can see, from a functional perspective there is no difference between the two types of signals: I can add units to both types, they both have a direction of flow, and they both have similar function blocks like adding, substracting... Only for physical signals the available types of blocks is very limited. Why didn't the matlab guys just use normal simulink lines instead of the physical signals?
Physical signals, unlike Simulink signals, have units associated with them. This means that they follow a number of rules, for example to ensure that the right unit is used (e.g. you can't add kg and m/s). From the documentation:
Using the Physical Signal Ports
The following rules apply to Physical Signal ports:
You can connect Physical Signal ports to other Physical Signal ports with regular connection lines, similar to Simulink signal
connections. These connection lines carry physical signals between
Simscape blocks.
You can connect Physical Signal ports to Simulink ports through special converter blocks. Use the Simulink-PS Converter block to
connect Simulink outports to Physical Signal inports. Use the
PS-Simulink Converter block to connect Physical Signal outports to
Simulink inports.
Physical Signals can have units associated with them. Simscape block dialogs let you specify the units along with the parameter
values, where appropriate. Use the converter blocks to associate units
with an input signal and to specify the desired output signal units.
Any sensor block in Simscape (in whatever physical domain) will output a physical signal. You can then convert it into a normal Simulink for feed to your controller. Similarly, any source block in Simscape (in whatever physical domain) will take a physical signal as input.
I suggest you just read the Simscape product page
In particular,
Simscape components represent physical elements, such as pumps, motors, and op-amps. Lines in your model that connect these components correspond to physical connections in the real system that transmit power.
Accompanying that description is the following image, which shows how Simscape models can be far more intuitive to build than a model which uses standard signal. This means models are far more maintainable and clearer to, for example, engineers who may not have a comp-sci background.
Let's delve into what a "physical connection" is somewhat.
[Simscape] employs the Physical Network approach, which differs from the standard Simulink modeling approach and is particularly suited to simulating systems that consist of real physical components.
[ ... ]
Each system is represented as consisting of functional elements that interact with each other by exchanging energy through their ports.
You stated in your question that both methods have a flow direction. This is wrong!
Simscape blocks try and balance the energy between the inlet(s) and outlet(s). For instance a fixed orifice in a fluid system may have high pressure on one side. Simscape will try and solve the pressure balance each iteration. You would need some custom Simulink subsystem to achieve this if not for Simscape.
What is the added value of simscape physical signals compared to normal simulink signals?
What is it that you think Simscape physical signals provide? Is it one number? How do you solve a mass-spring-damper system with just position? It's position AND it's speed AND it's acceleration.
I can add units to both types
No you can't. You put whatever you want in Simulink. You don't get to choose anything about what's in the physical signal in Simscape. You can specify units in the blocks that the signals connect, but you don't get to pick what the pipe itself is carrying.
they both have a direction of flow
No they don't. Your head and your torso are connected. There's no directionality to this. They're just connected. The physical signal is likewise just showing that (things) are physically connected. Again, the mass-spring-damper system: If the damper points to the mass, and the spring points to the mass, then is there any possibility that the damper could affect the spring? Yes, of course. The damper affects the spring because the damper affects the mass and the mass affects the spring.
The spring affects the mass, and the mass affects the spring. The signal is bidirectional. You're confusing signal directionality with kinematic chains.
they both have similar function blocks like adding, substracting
If you're on a train that's going 30 mph, and you're walking forward at 3 mph, how fast are you going relative to the world frame? What if you're walking backward? There is a physical meaning in adding and subtracting physical signals.
[For] physical signals the available types of [function blocks are] very limited
What is it that you're thinking they're missing? Can you also provide a description of what the physical meaning of that function block would be?
Why didn't the matlab guys just use normal simulink lines instead of the physical signals?
Because they're not the same. The biggest point is probably that Simscape is signal + derivative + second derivative, but again they're just conceptually different. Simulink is an easy way to write code - do this step, move along the arrow, do the next step, etc. Simscape is a pictorial representation of a physical system. The physical signal lines just show that things are connected. The system gets solved simultaneously.
I don't think it's mainly about the enforcement of physical signal units, nice though this is.
I think it's about the solver - and before it gets to the solver, about the choice of states and equation causality - rearranging the equations ready to be solved.
Simulink doesn't have any truck with this and just gets straight on with integrating signals as a succession of samples. I know it gets complicated with variable step solvers, but they are only doing extra fancy numerical analysis with the sampled data. Integration and the here-and-now is what it's all about!
Simscape just starts with a bucket of variables and a bucket of equations that variously depend on said variables. A 'bipartite graph', I believe they call it.
Just as we have to navigate a route through simultaneous equations to pick off the simple ones and substitute (or the matrix equivalents of this) Simscape has to do likewise in software so wants to keep alive augmented info on signals like which equations they are in and whether it knows or can easily obtain their derivatives, what they are, etc. Physical signals behave for us users just like Simulink signals, but I reckon they are there to provide the valuable service to Simscape of keeping this augmented info alive and linked between blocks so that one massive matrix equation can be formed for the whole system, not separate ones that get sampled as Simulink systems between Simulink blocks.
This rearrangement of equations ready for the more conventional solver getting stuck in is a black art indeed! We learn very little of how Simscape does it from the MathWorks docs, but you can install OpenModelica for free and see how that does it.
I was wondering if it is possible to use simlink's PID architecture in matlab to actually control hardware - rather than modelling it.
I have been playing around a little with the PID tuning in matlab - and have worked out the correct gains for my system (or at least good enough).
Now I want to implement the actual control loop in matlab using the real hardware. In this case I am tying to stabilise a laser using a measurement from a wavemeter - although from the point of view of matlab essentially I have two functions - one which returns the current wavelength, and another which alters the wavelength with an input from 0-100.
How do I get the fancy PID objects to work in a loop where for example I input data each loop, and get the required output to stabilise things given my gains - or should I just hardcode the equations in?
I have tried looking through some of the simlink examples - but there doesn't seem to me much actual implementation - mostly just modelling.
Thanks in advance for any advice.
MATLAB (without Simulink, or with Simulink in purely a simulation mode) is not a real-time environment. Trying to use it to control hardware in real-time won't work unless you have very slow sample rates.
If you do have slow sample rates, then you'd connect to your hardware to MATLAB using device drivers such as those in the Data Acquisition Toolbox
You haven't found any info on real-time implementation in the Simulink documentation because from Simulink the mechanism for real-time implementation is via Simulink Coder. You would need to use it in conjunction with a real-time environment such as Simulink Desktop Real-Time (if your sample rates are relatively slow), Simulink Real-Time, or one of many other 3rd party real-time form factors.
I am trying to train the robot for specific actions such as grasping or pointing by using the RNN.
The robot is composed of one arm and a head containing camera in it. Also the workspace will be the small table so that the arm and objects can be located.
The input of the recurrent neural network wiil be the image frame of every time steps from the camera and the output will be the target motor angle of next frame of the robot arm.
When the current image frame is fed to the network, the network outputs the motor value of arm for the next frame. And when the arm reaches the next position, the input frame in that position is again goes to the network and it again yields the next motor output.
However, when making the data for training, I have to make all the data of (image, motor angle) pair for all the position on the workspace. Eventhough the network can do some generalization job by itselt, the data needed is stil too much and it takes lots of time since there are too many trajectories.
Generalizing the problem I have, the time for getting training data for network is too much. Is there any way or method that can train network with small size dataset? Or making huge dataset within relatively small human intervention?
Your question is very broad and definitely encompasses more than field of study. This question cannot be answered in this platform, however, i suggest you to check out this compilation of Machine Learning Resources on gitHub, specifically Data Analysis section.
A more specific resource related to your question is DeepNeuralClassifier.
I searched more paper and I found some that are related to the subject. The main topic of my question was to
find the way to train the network efficiently with small size of dataset
find the way to make huge dataset with small human effort
There were some papers and two of them helped me a lot. This is the link.
Explanation-Based Neural Network Learning for Robot Control
Supersizing Self-supervision: Learning to Grasp from 50K Tries and 700 Robot Hours
I am working on a independent project. I am studying chemistry in school, along with computer science and would like to know if it is possible to model certain wave function phenomenon (schroedinger's equation, hamiltonians, eigenvalues) using Artificial Neural Networks.
My main questions are:
Would I be able to program and compute from my laptop? My laptop is a Asus Q200e
If not possible from laptop would I be able to use my desktop which contains a i5 processor and a fast GPU?
Your questions
Yes, may use your Asus Q200e to calculate your neural network.
Using a more powerful computer is always appreciative. If are willing to go the extra mile and perform the calculations on your GPU, the process will be even faster.
Applying neural networks to quatum mechanics
There is actually some litterature on how to proceed with creating such neural networks. See this link for to get a few pointers:
Artificial neural network methods in quantum mechanics
I am trying to make a neural network for approximation of some unkown function (for my neural network course). The problem is that this function has very many variables but many of them are not important (for example in [f(x,y,z) = x+y] z is not important). How could I design (and learn) network for this kind of problem?
To be more specific the function is an evaluation function for some board game with unkown rules and I need to somehow learn this rules by experience of the agent. After each move the score is given to the agent so actually it needs to find how to get max score.
I tried to pass the neighborhood of the agent to the network but there are too many variables which are not important for the score and agent is finding very local solutions.
If you have a sufficient amount of data, your ANN should be able to ignore the noisy inputs. You also may want to try other learning approaches like scaled conjugate gradient or simple heuristics like momentum or early stopping so your ANN isn't over learning the training data.
If you think there may be multiple, local solutions, and you think you can get enough training data, then you could try a "mixture of experts" approach. If you go with a mixture of experts, you should use ANNs that are too "small" to solve the entire problem to force it to use multiple experts.
So, you are given a set of states and actions and your target values are the score after the action is applied to the state? If this problem gets any hairier, it will sound like a reinforcement learning problem.
Does this game have discrete actions? Does it have a discrete state space? If so, maybe a decision tree would be worth trying?