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Engineering project, leaving cert 2012

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Comments

  • Registered Users Posts: 166 ✭✭TW Mr Tayto


    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 (:


  • Closed Accounts Posts: 47 Kieran Lad


    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.


  • Registered Users Posts: 85 ✭✭Bomber6


    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)?


  • Closed Accounts Posts: 29 Fiendish Human


    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.


  • Closed Accounts Posts: 383 ✭✭fullback4glin


    It's up to yourself really


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  • Closed Accounts Posts: 29 Fiendish Human


    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?


  • Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    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.


  • Closed Accounts Posts: 29 Fiendish Human


    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?


  • Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    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.


  • Closed Accounts Posts: 29 Fiendish Human


    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! :D


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  • Registered Users Posts: 661 ✭✭✭Mayo_Boy


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


  • Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    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.


  • Registered Users Posts: 661 ✭✭✭Mayo_Boy


    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


  • Closed Accounts Posts: 47 Kieran Lad


    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?


  • Registered Users Posts: 3 Bigbaddan


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


  • Registered Users Posts: 661 ✭✭✭Mayo_Boy


    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.


  • Registered Users Posts: 2,965 ✭✭✭laoch na mona


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

    please I need the help


  • Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    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


  • Closed Accounts Posts: 1 helpneeded2012


    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:)


  • Registered Users Posts: 21 grizzly700


    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"


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  • Registered Users Posts: 25 Lausie93


    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 :)


  • Closed Accounts Posts: 29 Fiendish Human


    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 :)


  • Closed Accounts Posts: 29 Fiendish Human


    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.


  • Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    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.


  • Registered Users Posts: 139 ✭✭Alexzont


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


  • Registered Users Posts: 21 grizzly700


    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?


  • Registered Users Posts: 25 Lausie93


    @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 :)


  • Closed Accounts Posts: 29 Fiendish Human


    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: 2WuHz.png


  • Registered Users Posts: 25 Lausie93


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

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


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  • Closed Accounts Posts: 29 Fiendish Human


    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! :D


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