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!
I wanted to simulate the Sent_Protocol with an STM32 μC emulate as if I had a sensor. and represent this with an oscilloscope . I have to simulate this on Matlab and then connect with STM32. so i thought the signal should be like a normal PWM Signal look like.
So I wanted to ask if it is possible to generate a different pulse width in the same signal as in the above picture ?
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'm beginner in contiki in cooja. I want to simulate two networks. each networks has some sensor nodes and a sink node. Sensor's firmware is same but only for example sensors of one network sense temperature and another sense acceleration. The networks communicate with other through their sink node. I want to use examples in contiki os. It's not important what protocol is used. My object is only simulation and I want to understand code of example. I check udp-sink.c and udp-sender.c in examples/ipv6/rpl-collect path for my work. I want to use simple example. What a suggestion for source code of nodes and what reference is there for understanding of contiki codes?
I recently was introduced to the amazing world of neural networks. I've noticed their amazing flexibility and capability. However, I'm no gonna lie, my knowledge about their technicalities is sparse. The network of interest is the multilayer perceptron. It consists of some input nodes, some hidden nodes and some output nodes. However, I would like to know, do all input nodes need to be connected to all hidden nodes and all hidden nodes need to be connected to all output nodes? Or is there some determining factor to decide which input nodes should be connected to which hidden nodes which are in turn connected to which output nodes?
Your help is much appreciated :3
do all input nodes need to be connected to all hidden nodes and all
hidden nodes need to be connected to all output nodes?
Since an Multi-Layer Perceptron (MLP) is a Fully Connected Network, each node in one layer connects with a certain weight W{i,y} to every node in the following layer. See the image bellow.
Or is there some determining factor to decide which input nodes should be connected to which hidden nodes which are in turn connected to which output nodes?
You can implement pruning methods to remove some connections and observe if it improves the accurancy and performance of the neural network. Generally, it is made after you train your neural network model and you can see the performance. See these links:
A new pruning algorithm for neural network
An iterative pruning algorithm for feedforward neural networks
It also could be made by exaustive search, on other words, brute force (removing and reconnecting nodes between each layers).