CN2
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#1
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#1
So I'm studying higher engineering this year (crashing!) But we've just started the assignment and I'm finding it quite difficult. I look on the SQAs understanding standards website but for some reason there don't appear to be any examples? It's worth 40% of my grade and I don't want to mess it up! Can anyone help?
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Smack
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#2
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#2
(Original post by CN2)
So I'm studying higher engineering this year (crashing!) But we've just started the assignment and I'm finding it quite difficult. I look on the SQAs understanding standards website but for some reason there don't appear to be any examples? It's worth 40% of my grade and I don't want to mess it up! Can anyone help?
What is the assignment? If you post something specific that you are struggling with, someone may be able to help.
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CN2
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#3
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#3
(Original post by Smack)
What is the assignment? If you post something specific that you are struggling with, someone may be able to help.
We have to design a hydroelectric system with a turbine and generator, etc. So I've made a specification and system diagrams. I've also completed my electronic circuit and flowchart. We have to now work on the structural and mechanical side and do calculations based on this but I don't even know where to start! I'm also struggling a bit with layout so if anyone's done it before it'd help a lot!
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Smack
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#4
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#4
(Original post by CN2)
We have to design a hydroelectric system with a turbine and generator, etc. So I've made a specification and system diagrams. I've also completed my electronic circuit and flowchart. We have to now work on the structural and mechanical side and do calculations based on this but I don't even know where to start! I'm also struggling a bit with layout so if anyone's done it before it'd help a lot!
I've never done layouts before so I can't help with that I am afraid, but I may be able to help with the mechanical and structural calculations, if you could provide more information of your design so far, what equipment you have and what you have to calculate.
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Joinedup
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#5
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Fwliw there's an interesting and quite serious (town evacuated) ongoing situation with the Hyatt hydro plant / Oroville dam complex in California... might give you a few ideas for considerations for your design & be able to inject a topical example or two.. at least be able to say something about not routing your power transmission lines out with the pylons placed on the emergency spillway...

https://en.wikipedia.org/wiki/Oroville_Dam_crisis

https://www.youtube.com/watch?v=Wiki...0-001a11484386

Some crazy conspiracy theory crap on YT as you'd expect but the guy above seems to have produced a decent series of videos on it (which I've been following out of personal geekyness)
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CN2
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#6
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#6
(Original post by Smack)
I've never done layouts before so I can't help with that I am afraid, but I may be able to help with the mechanical and structural calculations, if you could provide more information of your design so far, what equipment you have and what you have to calculate.
Okay thanks! So basically we have a water speed sensor, this is a difference amplifier which compares the desired speed to the speed of a generator (connected to a motor in the water). This has to go through a microcontroller to control three outputs. One is a seven segment display (and decoder) to show a value for the speed. The second is an led to light when flow speed is too high and the third is a motor which operates a gate (which opens or closes to let different amounts of water through). Two and three are controlled by a half h driver. I'm really struggling to understand what values I should have in my difference amplifier.

For the mechanisms and structures part we know that the system is supported by a beam and we need to work out its dimensions and the force the beam needs to exert to support it. I just can't seem to get my head around it!

Thanks again!
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CN2
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#7
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#7
(Original post by Joinedup)
Fwliw there's an interesting and quite serious (town evacuated) ongoing situation with the Hyatt hydro plant / Oroville dam complex in California... might give you a few ideas for considerations for your design & be able to inject a topical example or two.. at least be able to say something about not routing your power transmission lines out with the pylons placed on the emergency spillway...

https://en.wikipedia.org/wiki/Oroville_Dam_crisis

https://www.youtube.com/watch?v=Wiki...0-001a11484386

Some crazy conspiracy theory crap on YT as you'd expect but the guy above seems to have produced a decent series of videos on it (which I've been following out of personal geekyness)
That sounds pretty interesting! Thanks!
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Smack
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#8
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(Original post by CN2)
Okay thanks! So basically we have a water speed sensor, this is a difference amplifier which compares the desired speed to the speed of a generator (connected to a motor in the water). This has to go through a microcontroller to control three outputs. One is a seven segment display (and decoder) to show a value for the speed. The second is an led to light when flow speed is too high and the third is a motor which operates a gate (which opens or closes to let different amounts of water through). Two and three are controlled by a half h driver. I'm really struggling to understand what values I should have in my difference amplifier.

For the mechanisms and structures part we know that the system is supported by a beam and we need to work out its dimensions and the force the beam needs to exert to support it. I just can't seem to get my head around it!

Thanks again!
What sort of material have you covered so far? To be honest, what you're doing sounds like no small undertaking. Are you getting plenty of support from your teacher to complete this assignment?

Anyway, before you can do the structural calculations, you need to know what the overall physical system looks like and the loads applied to it. Do you have any drawings, sketches or maybe a CAD model?
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CN2
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#9
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#9
(Original post by Smack)
What sort of material have you covered so far? To be honest, what you're doing sounds like no small undertaking. Are you getting plenty of support from your teacher to complete this assignment?

Anyway, before you can do the structural calculations, you need to know what the overall physical system looks like and the loads applied to it. Do you have any drawings, sketches or maybe a CAD model?
It is quite a lot work and worth 40% of my grade this year! We've got the brief and the teacher can help once we've completed each section, it's just getting started!

I don't have any of that but I need to design it I suppose....
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Joinedup
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#10
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#10
(Original post by CN2)
Okay thanks! So basically we have a water speed sensor, this is a difference amplifier which compares the desired speed to the speed of a generator (connected to a motor in the water). This has to go through a microcontroller to control three outputs. One is a seven segment display (and decoder) to show a value for the speed. The second is an led to light when flow speed is too high and the third is a motor which operates a gate (which opens or closes to let different amounts of water through). Two and three are controlled by a half h driver. I'm really struggling to understand what values I should have in my difference amplifier.

For the mechanisms and structures part we know that the system is supported by a beam and we need to work out its dimensions and the force the beam needs to exert to support it. I just can't seem to get my head around it!

Thanks again!
Have you done any control theory yet?

Well that's closed loop control - the inputs to the differential amplifier (called a comparator in this application) are the reference voltage (setpoint) on the + input and the voltage corresponding to the output from your speed sensor.on the - input.

Image
Basically your job is to arrange things so that the speed sensor produces a voltage equal to the reference voltage at the desired flow rate... when the inputs are equal the output of the comparator will be an 'error' of zero and the system will not make any change to the valve position.

if the flow rate is too high,then the voltage from the flow sensor is greater than the reference voltage and the output of the comparator is driven negative... which will be a command to your motor driver to turn the motor in the direction which reduces the flow rate.

otoh if the flow rate is too low the voltage from the flow sensor is less than the reference voltage and the output from the comparator is driven positive which will command the motor driver to rotate the motor in the direction which increases the flow rate.

fingers crossed it'll automatically and continuously seek the flow rate corresponding to the setpoint and then stop when it gets there without doing anything naughty (like oscillating)

obviously there's a good deal of complexity and maths involved in doing a thorough job of it
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Smack
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#11
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#11
(Original post by CN2)
It is quite a lot work and worth 40% of my grade this year! We've got the brief and the teacher can help once we've completed each section, it's just getting started!

I don't have any of that but I need to design it I suppose....
In this instance, the structure would probably be designed last, as the point of the structure is to support the mechanical and electrical equipment. So in order to actually design the structure, you would need to know (or have a good idea) of the weights of all of the other equipment you are using and where they would be located.

Have you covered stress/structural calculations before?
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CN2
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#12
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#12
(Original post by Joinedup)
Have you done any control theory yet?

Well that's closed loop control - the inputs to the differential amplifier (called a comparator in this application) are the reference voltage (setpoint) on the + input and the voltage corresponding to the output from your speed sensor.on the - input.

Image
Basically your job is to arrange things so that the speed sensor produces a voltage equal to the reference voltage at the desired flow rate... when the inputs are equal the output of the comparator will be an 'error' of zero and the system will not make any change to the valve position.

if the flow rate is too high,then the voltage from the flow sensor is greater than the reference voltage and the output of the comparator is driven negative... which will be a command to your motor driver to turn the motor in the direction which reduces the flow rate.

otoh if the flow rate is too low the voltage from the flow sensor is less than the reference voltage and the output from the comparator is driven positive which will command the motor driver to rotate the motor in the direction which increases the flow rate.

fingers crossed it'll automatically and continuously seek the flow rate corresponding to the setpoint and then stop when it gets there without doing anything naughty (like oscillating)

obviously there's a good deal of complexity and maths involved in doing a thorough job of it
Okay thank you! That definitely helps!
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CN2
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#13
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#13
(Original post by Smack)
In this instance, the structure would probably be designed last, as the point of the structure is to support the mechanical and electrical equipment. So in order to actually design the structure, you would need to know (or have a good idea) of the weights of all of the other equipment you are using and where they would be located.

Have you covered stress/structural calculations before?
Okay I'll work that out first then. We've covered them quite briefly, yeah!
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