Engineering project, leaving cert 2012

Neodymium · 20-10-2011 11:20pm

mousi wrote: »

No you wouldnt because all the brief says about the steering is that it should hace "a stteering mechanism for the front wheels" it doesnt say it has to be electric or manual, so it can be either.

Definition of a mechanism:

mechanism

1. (Engineering / Mechanical Engineering) a system or structure of moving parts that performs some function, esp in a machine
2. something resembling a machine in the arrangement and working of its parts the mechanism of the ear
3. (Engineering / Mechanical Engineering) any form of mechanical device or any part of such a device

The brief:

The LRV should:
a) Have propulsion units to provide individual drives for both front wheels;
b) Incorporate a central switching console to operate the front wheels;
c) Include a steering mechanism for the front wheels;
d) Have seating capacity for the driver only.

From point 'a' it says propulsion units (notice the plural) with individual drives for both wheel, so there should be more than one motor. By having a motor for each wheel then you already have an electrical steering 'mechanism'. If the LRV only has to steer using its motors, then point 'a' would encompass point 'c', so why would they include point 'c'? They would be making it far too easy if you only had to have it steering by varying the speed of each motor.

I'd say you would be safer including the individual motor for each wheel and some sort of a mechanical steering mechanism.

I've got something like a rack in pinion in mind, something like this maybe:

The rectangular blocks at each side are a motor and gearbox in one, they're very compact and have a lot of torque. I don't have the pinion shown, but when it is turned clockwise the rack moves to the left and right when anti-clockwise. The rack is connected to the motors by a bracket which pivots where the screw is shown.

conorfitz · 24-10-2011 12:34am

Hi, Just wondering what kind of software you used to make that image?

fullback4glin · 24-10-2011 3:08pm

SolidWorks I'd be guessing

Leftyflip · 25-10-2011 4:50pm

So where are people at in their projects now? Anybody made a start on the actual model?

fullback4glin · 25-10-2011 6:14pm

Just finishing off investigation and research... Next stage is making a cardboard model, might start it over midterm

Sherman_ator · 26-10-2011 3:33pm

Made an account just to offer this idea,As I myself am debating over whether or not it would be accepted;
Why not have 2 arrays of Dual AA batteries?Im not sure what the motor performance would be like but power output would be well below 9V.It would also save me having to dick around with circuits,instead I just have a battery,switch and motor to deal with

spurious · 26-10-2011 9:21pm

Having worked for the SEC, I wouldn't advise candidates to post images or specific details of their exam work on boards.

General discussion of materials or construction is fine, but personally I'd steer clear of anything too specific.

TW Mr Tayto · 27-10-2011 8:17pm

I've never been the best guy for electronics, I love them to bits; but we've never really done more than brush over them in school.

Could I have a 9V battery powering my wheels, and a small (say a watch battery or two) powering something else?
Would the project be discounted if the TOTAL voltage was more than 9V? They'd be on different circuits.

Bigbaddan · 27-10-2011 10:35pm

Hey everyone,
I have read the brief and everythin bout 2 different motors for each wheel but the only real thing thts botherin me is the steering mechanism! Is there sometin I could use that can pivot the wheels and have the both turn left and right??

Cheers

partyatmygaff · 27-10-2011 10:50pm

TW Mr Tayto wrote: »

I've never been the best guy for electronics, I love them to bits; but we've never really done more than brush over them in school.

Could I have a 9V battery powering my wheels, and a small (say a watch battery or two) powering something else?
Would the project be discounted if the TOTAL voltage was more than 9V? They'd be on different circuits.

You won't lose marks for exceeding 9V. You'll lose marks for redundant weight. Unless you've got a solid reason for including two independently powered circuits then you should stick to one power source and just use that to supply power to all your electronics.

If I were you, i'd use stripboard or a simple PCB to make a power supply of some sort. Just connect a 9V battery to different voltage regulators and you'll have your own multi-voltage power supply. A much more impressive solution than mounting batteries on every section of your project.

TW Mr Tayto · 27-10-2011 11:22pm

partyatmygaff wrote: »

You won't lose marks for exceeding 9V. You'll lose marks for redundant weight. Unless you've got a solid reason for including two independently powered circuits then you should stick to one power source and just use that to supply power to all your electronics.

If I were you, i'd use stripboard or a simple PCB to make a power supply of some sort. Just connect a 9V battery to different voltage regulators and you'll have your own multi-voltage power supply. A much more impressive solution than mounting batteries on every section of your project.

Thanks!
I was thinking of the standard drive circuit, then a small one with a luminated toggle switch (or momentary) to power some high intensity LED headlights.
I had never thought of the PCB, thanks (:

Kieran Lad · 28-10-2011 11:28pm

I miss the real engineering projects, can crushers etc

These projects are just the same as junior cert only you need to put in alot more effort. This "buggy" is tricky enough.
I started doing a few drawings and mock models this week, I got a few ideas for steering, but noting major. My first was to use a motor for steering, but don't want to get dragged down on that, as it don't need to be electronic.

Bomber6 · 29-10-2011 10:45am

I assume everyone is free to make interpretations of what is required (So long as they're reasonable)?
For example, does the "central" steering console have to be physically "central" or central in that in consolidates all the controls in one place (and could actually be mounted on a remote controller attached by a wire)?

Fiendish Human · 31-10-2011 11:34pm

Does the "Central Switching Console" need to be located on the LRV or in a remote control? I was under the impression that it should be on the vehicle itself, but after reading some of this thread I see that some are putting it in a separate remote control.

fullback4glin · 31-10-2011 11:36pm

It's up to yourself really

Fiendish Human · 31-10-2011 11:39pm

fullback4glin wrote: »

It's up to yourself really

Thanks! On a side note: I was leaving acrylic out of my design because I thought that building space equipment out of plastic was a bit risk-ay, but is it acceptable to use acrylic?
Secondly: Do marks go for building a cardboard model? If so, would a virtual model on SolidWorks suffice?

partyatmygaff · 31-10-2011 11:52pm

Fiendish Human wrote: »

Thanks! On a side note: I was leaving acrylic out of my design because I thought that building space equipment out of plastic was a bit risk-ay, but is it acceptable to use acrylic?
Secondly: Do marks go for building a cardboard model? If so, would a virtual model on SolidWorks suffice?

It's perfectly acceptable to use acrylic where suitable. In fact, plastics (Albeit probably not bog standard acrylic) are more than likely used in some components of space equipment.

You don't necessarily get marks for a physical mock up but it does give off the right impression and it certainly helps you see flaws with your design early on in the process. I made two models for snowmobile, neither of which ended up being my final design. The first was un-steerable thanks to the chassis design and the second was far too tall and unstable. In the end I settled on taking the best features of both and putting them in to my final design. A solidworks model however is almost essential. A good idea is to have three or so different models made up in Solidworks and then choose one and create drawings from it for production.

Fiendish Human · 01-11-2011 12:12am

partyatmygaff wrote: »

It's perfectly acceptable to use acrylic where suitable. In fact, plastics (Albeit probably not bog standard acrylic) are more than likely used in some components of space equipment.

You don't necessarily get marks for a physical mock up but it does give off the right impression and it certainly helps you see flaws with your design early on in the process. I made two models for snowmobile, neither of which ended up being my final design. The first was un-steerable thanks to the chassis design and the second was far too tall and unstable. In the end I settled on taking the best features of both and putting them in to my final design. A solidworks model however is almost essential. A good idea is to have three or so different models made up in Solidworks and then choose one and create drawings from it for production.

Another question: relating to wheels; In a vacuum, wouldn't air filled tyres surely explode? And if so, are they expecting us to take that level of detail into account? Where do we draw the line with attention to detail?

partyatmygaff · 01-11-2011 12:37am

Fiendish Human wrote: »

Another question: relating to wheels; In a vacuum, wouldn't air filled tyres surely explode? And if so, are they expecting us to take that level of detail into account? Where do we draw the line with attention to detail?

They're not that fussed about minute details like that to be honest.

Take for example last year's snowmobile. Hardly any of the models that got As could actually function as a snowmobile. Not for lack of ability but for lack of practicality. Batteries and the cold don't go well together. Exposed electronics and snow also don't go well together. Exposed steel and snow is an even bigger no no yet despite all of these issues they were still marked highly.

All they're really looking for is clever design and suitable fabrication. That said, if you pay attention to details like the unfeasability of pneumatic tyres in space and mention it in the brief then it might impress the examiner. I'm not all too sure if the tyre would burst in vacuum but i'm fairly sure that the rubber used will start to degrade with the higher radiation on the moon.

Fiendish Human · 01-11-2011 12:59am

partyatmygaff wrote: »

They're not that fussed about minute details like that to be honest.

Take for example last year's snowmobile. Hardly any of the models that got As could actually function as a snowmobile. Not for lack of ability but for lack of practicality. Batteries and the cold don't go well together. Exposed electronics and snow also don't go well together. Exposed steel and snow is an even bigger no no yet despite all of these issues they were still marked highly.

All they're really looking for is clever design and suitable fabrication. That said, if you pay attention to details like the unfeasability of pneumatic tyres in space and mention it in the brief then it might impress the examiner. I'm not all too sure if the tyre would burst in vacuum but i'm fairly sure that the rubber used will start to degrade with the higher radiation on the moon.

Thanks for the advice!

Mayo_Boy · 01-11-2011 5:18pm

Does the LRV need to have four wheel steering of some sort?

partyatmygaff · 01-11-2011 7:39pm

Mayo_Boy wrote: »

Does the LRV need to have four wheel steering of some sort?

The brief doesn't mention anything about four wheel steering. No need for it anyway up on the moon. It doesn't need to have a tiny turning radius.

Mayo_Boy · 01-11-2011 8:12pm

partyatmygaff wrote: »

The brief doesn't mention anything about four wheel steering. No need for it anyway up on the moon. It doesn't need to have a tiny turning radius.

Thanks

Kieran Lad · 01-11-2011 11:07pm

partyatmygaff wrote: »

The brief doesn't mention anything about four wheel steering. No need for it anyway up on the moon. It doesn't need to have a tiny turning radius.

The Actual LRV did have four wheel turning though :pac:

I searched the net and only found one example of the LRV, its common just having a seat, sat dish and wheels. Given that most finished projects are going to look the same, should we actually incorporate some of the ideas the actual one as to make it different, as in make it fordable?

Bigbaddan · 02-11-2011 1:39pm

so the easiest option for the steering would be a rack and pinion???

Mayo_Boy · 03-11-2011 3:41pm

Would anybody be kind enough to give me a list of what I should put in each section of the folio? e.g. Investigation of solutions
Or even better, email me a portfolio from last year?
Cheers.

laoch na mona · 04-11-2011 6:15pm

would anyone donate a folder lay out to a needy sixth year

please I need the help

partyatmygaff · 04-11-2011 6:45pm

I'd post mine but I don't think i'm allowed as it's being entered in to a competition.

That said, back when I was in fifth year someone posted up their brief here on the forum. As far as I remember they said it got them an A. I'll repost it here on their behalf. All credit goes to the author.

http://www.scribd.com/doc/71597183/Leaving-Certificate-Engineering-2009

helpneeded2012 · 08-11-2011 12:01am

not happy seems very difficult, only took up engineering in 5th year havent done much practical and im clueless as to motors steering mechanisms ect.. any help or ideas would be appreciated:)

grizzly700 · 08-11-2011 1:00pm

Any one know how long of a write up you'd need to get good marks? Also if you have two 9 volt motors for the front wheels (18volts combined) is that exceeding the limit as stated in the Brief " (c) Electric power does not exceed 9volts"

Lausie93 · 08-11-2011 8:23pm

I'm here trying to get my final design drawn up and am so annoyed i could cry with this confusing project!!

Could anybody please explain does the brief state that the two front wheels must be able to steer independently? For example could they have a rack and pinion (that would turn them both in the same direction) and only have separate motors? Would that satisfy the brief?

Any help would be really appreciated

Fiendish Human · 08-11-2011 9:36pm

Lausie93 wrote: »

I'm here trying to get my final design drawn up and am so annoyed i could cry with this confusing project!!

Could anybody please explain does the brief state that the two front wheels must be able to steer independently? For example could they have a rack and pinion (that would turn them both in the same direction) and only have separate motors? Would that satisfy the brief?

Any help would be really appreciated

The front wheels do not need to be steered separately. The LRV needs to be steered. A rack and pinion would do that. If anything, a car with wheels that steered in different directions would be impractical and difficult to operate.

A Rack and pinion would be fine. Just make sure that you use two motors for the front wheels. (One for each wheel)

Here's a pic that might help: It was posted a few pages back on this thread https://us.v-cdn.net/6034073/uploads/attachments/445708/178767.png

A word of advice: Don't complicate things, the brief means exactly what it says

Fiendish Human · 08-11-2011 9:46pm

grizzly700 wrote: »

Any one know how long of a write up you'd need to get good marks? Also if you have two 9 volt motors for the front wheels (18volts combined) is that exceeding the limit as stated in the Brief " (c) Electric power does not exceed 9volts"

You may be docked marks because it is impractical. Personally, I don't see why you would use two circuits. If circuits aren't your thing then ask your teacher for help. Using two circuits is basically like taking a parallel circuit and splitting it in two.

Here's a video showing you how to build a parallel circuit: http://youtu.be/7M7XCcyWuQs

The fact that they used the word "power" instead of "potential difference" or "voltage" would suggest that they meant the sum of the voltages of the batteries and not the overall potential difference of the circuit(s); in that case, you would use one 9V battery. If they meant the overall potential difference of the circuit(s) then you could use as many 9V batteries in parallel as you want, but not in series. To stay on the safe side I'd stick to one 9V battery, it's all you need really.

partyatmygaff · 08-11-2011 9:55pm

There's no problem whatsoever with using two 9V batteries. In fact there's no issue whatsoever with you using any amount of batteries or having any amount of independent circuits so long as there's a logical reason for it and not just lazy design.

The brief only says that your power source cannot exceed 9V. Two 9V batteries wired in parallel won't exceed 9V so there's no problem there.

As an aside, if you ever actually needed more than 9V (Which you shouldn't unless you're going for something very fancy) then you could even use a voltage regulator to get higher voltages while still remaining true to the brief.

Alexzont · 08-11-2011 10:15pm

I was wondering what size chassis everyone was going for because 35cm seems a bit to large?

grizzly700 · 08-11-2011 10:31pm

Haven't a clue about electrics never did anything with them but thanks. Has anyone any tips on how to write up the folio or how long are yours going to be?

Lausie93 · 09-11-2011 12:08am

@Fiendish Human, Thank you soo much, i thought that it would be impractical myself but convinced myself it was what the brief said and spent hours trying to figure out a steering mechanism (if only you could see my design made from elastic bands and pencils!), now that i could use a rack and pinion the project seems so much easier haha :P

And since Im useless at electronics, would you be able to wire two electric motors to one 9 volt battery and have them run properly??

Thanks again

Fiendish Human · 09-11-2011 2:59pm

Lausie93 wrote: »

@Fiendish Human, Thank you soo much, i thought that it would be impractical myself but convinced myself it was what the brief said and spent hours trying to figure out a steering mechanism (if only you could see my design made from elastic bands and pencils!), now that i could use a rack and pinion the project seems so much easier haha :P

And since Im useless at electronics, would you be able to wire two electric motors to one 9 volt battery and have them run properly??

Thanks again

Yep! If you take a look at that video I linked earlier, it shows you a parallel circuit with two bulbs. Replace the bulbs with motors, and there you go! Current will be distributed evenly over the two motors. Then put switches after each of the motors and you can control each of them separately.
This might put things into perspective for you:

Lausie93 · 09-11-2011 9:52pm

Ahh i understand now, you're only the best! thank you

What stage is everyone at with the portfolio and project??

Fiendish Human · 11-11-2011 7:45pm

Lausie93 wrote: »

Ahh i understand now, you're only the best! thank you

What stage is everyone at with the portfolio and project??

Research, Analysis of brief and some possible solutions done. I have a pretty good picture in my head of what I'm gonna do. Just need to figure out how the whole thing fits together, then I can start building!

Novenine · 13-11-2011 6:46pm

Hey guys, Having lots of trouble! I wanted to do the easy rack in pinion kind of thing but my teacher is mad.. one person in the class already has that idea and he won't let any of us use a rack pinion mechanism now. So I am researching my balls off now and had to scrap my design.
I'm looking at a Crossed Dual Drag Link, but can't figure out how it actually functions.. also I'm troubled as to how I'm going to attach motors to the wheels when the hub will already be full with the steering mechanism! http://www.ihpva.org/Projects/PracticalInnovations/weld.html the CDDL is on this page

partyatmygaff · 13-11-2011 7:54pm

Novenine wrote: »

Hey guys, Having lots of trouble! I wanted to do the easy rack in pinion kind of thing but my teacher is mad.. one person in the class already has that idea and he won't let any of us use a rack pinion mechanism now. So I am researching my balls off now and had to scrap my design.

That's ridiculous. That's as daft as saying "Ah, they're using round wheels in their project. You can't use round wheels as well or it will look like you copied their idea.". Rack and Pinions are almost a standard when it comes to model steering mechanisms. Expecting twenty or so people to come up with completely different steering mechanisms is crazy.

Novenine · 13-11-2011 8:23pm

partyatmygaff wrote: »

That's ridiculous. That's as daft as saying "Ah, they're using round wheels in their project. You can't use round wheels as well or it will look like you copied their idea.". Rack and Pinions are almost a standard when it comes to model steering mechanisms. Expecting twenty or so people to come up with completely different steering mechanisms is crazy.

I know, but he won't let me do it, he said something about not verifying its my work if I go ahead with it. I had an entire design completed and I had to scrap it!

partyatmygaff · 13-11-2011 8:28pm

Novenine wrote: »

I know, but he won't let me do it, he said something about not verifying its my work if I go ahead with it. I had an entire design completed and I had to scrap it!

Complain to your Principal and have your principal deal with him. That's ridiculous. Putting you under extra stress, delaying your project and potentially costing you a grade or two just because of his own daft opinions is not on.

Although, that said, if you could design something that worked more elegantly than a rack and pinion then that could very well improve your mark.

Novenine · 13-11-2011 9:07pm

partyatmygaff wrote: »

Complain to your Principal and have your principal deal with him. That's ridiculous. Putting you under extra stress, delaying your project and potentially costing you a grade or two just because of his own daft opinions is not on.

Although, that said, if you could design something that worked more elegantly than a rack and pinion then that could very well improve your mark.

Cheers for the concern man, but our principal wouldn't dare cross him, Complaining will just get us thrown out of the classroom, meaning no grade :L
F'd up system in our school. I only started engineering in 5th year..
So basically I'm trying to design an entirely unique steering mechanism, I have a few little cardboard model mechanisms made here, just having a problem attaching a motor to each front wheel..
I have a bar going into the centre of the wheel already, how can I get a motor to turn the wheel then?

Oh also, our teacher has complained about suspension on these LRVs, he says its impractical and unnecessary for the moon.

partyatmygaff · 13-11-2011 9:18pm

Novenine wrote: »

Cheers for the concern man, but our principal wouldn't dare cross him, Complaining will just get us thrown out of the classroom, meaning no grade :L
F'd up system in our school. I only started engineering in 5th year..
So basically I'm trying to design an entirely unique steering mechanism, I have a few little cardboard model mechanisms made here, just having a problem attaching a motor to each front wheel..
I have a bar going into the centre of the wheel already, how can I get a motor to turn the wheel then?

Oh also, our teacher has complained about suspension on these LRVs, he says its impractical and unnecessary for the moon.

http://dayton.hq.nasa.gov/IMAGES/MEDIUM/GPN-2000-001289.jpg
http://www.kasmamagazine.com/images/relativebabble/surface-of-moon.jpg

Let me get this straight... your Engineering teacher told you that suspension is impractical and unnecessary on the moon?

Erm...

Novenine · 13-11-2011 9:31pm

partyatmygaff wrote: »

http://dayton.hq.nasa.gov/IMAGES/MEDIUM/GPN-2000-001289.jpg
http://www.kasmamagazine.com/images/relativebabble/surface-of-moon.jpg

Let me get this straight... your Engineering teacher told you that suspension is impractical and unnecessary on the moon?

Erm...

:L Exactly! I said about all the terrain and he started talking to me as if I was stupid- He like put words in my mouth making it sound like I thought the gravity was just like on earth. Gah, Boards.ie is my new engineering teacher

Fiendish Human · 15-11-2011 11:03pm

Novenine wrote: »

Cheers for the concern man, but our principal wouldn't dare cross him, Complaining will just get us thrown out of the classroom, meaning no grade :L
F'd up system in our school. I only started engineering in 5th year..
So basically I'm trying to design an entirely unique steering mechanism, I have a few little cardboard model mechanisms made here, just having a problem attaching a motor to each front wheel..
I have a bar going into the centre of the wheel already, how can I get a motor to turn the wheel then?

Oh also, our teacher has complained about suspension on these LRVs, he says its impractical and unnecessary for the moon.

No offence to your engineering teacher but that is quite possibly the most ridiculous statement of the century. Suspension not necessary on the moon?....Wow is all I can say. As for the rack and pinion idea... Coming up with an entirely original steering system would have to be the work of genius, it's a leaving certificate project... not NASA. I second what partyatmygaff said: reserving such a broad idea to one student is preposterous! I hope for your sake that your taking the piss here, if not then talk to some of your school's other tech teachers.

ghilliemaster · 16-11-2011 4:44pm

Hi lads
what i was thinking of doing was a simple,yet good looking roll cage type shell.looks great a guy in my class did it for the junior and it looked very impresive.joined it together with solder and it was sturdy.Any ideas on that?.Also ye think we would have to put a satelite type deal on it?? it being a lrv and all!
any one started on the second part of the folio.Having a spot of trouble with it

Fiendish Human · 16-11-2011 5:27pm

ghilliemaster wrote: »

Hi lads
what i was thinking of doing was a simple,yet good looking roll cage type shell.looks great a guy in my class did it for the junior and it looked very impresive.joined it together with solder and it was sturdy.Any ideas on that?.Also ye think we would have to put a satelite type deal on it?? it being a lrv and all!
any one started on the second part of the folio.Having a spot of trouble with it

Cool idea! Over-crossing bars would be quite sturdy and light indeed!

As for the satellite: Not entirely necessary. Yes, LRVs in reality would have some satellites, but seeing as your making a model of an LRV, a satellite would really just be for decoration. My advice: build the thing, and if you have any time left over then add your satellite, astronaut manikin, logos etc. Focus on the tasks in the brief first (i.e. the steering, the individual motor drives etc.) then tackle the extras.

Engineering project, leaving cert 2012

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