USING PARAMETERS FOR A ROCKER BOGIE HELP

[Anonymous]

So I m trying to optimize a rocker bogie suspension system but I am running into a few problems using the parameters. I am having problems with my parameter "L4" it should be a Patagonian equation for a triangle length: (S1^2+(2R))^(-1) but when I try it on my calculator I get different values then the nominal. I also get the text in red. I hope this is the cause for it not being able to finish the constraints since i am fairly certain my parameters I derived are correct. I attached images of what I am trying to do and what the inventor software is showing

thanks, Sage Edwards

CORRECTION: found that I can define L4 as L4=H1

also the angle between the bogie arms is constrained to 90deg

Update: I am thinking i need to revisit my equations but if i can get an explanation for the red text that would be great

[JDMather]

It doesn't look to me like you have accounted for your units.

I recommend that you right out the equation on paper with the units included.

[Anonymous]

my equations are not dependent on units they are just basic trig and geometry equations. I am checking my equations on paper now but that doesn't explain the red error text. Did I type it in wrong? 

[Anonymous]

Additional question: I would like to make R (radius of wheel) to be a variable) Is this something I can do? 

[JDMather]

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@Anonymous wrote:

my equations are not dependent on units .... 

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R is in mm
S1 is in mm

L4 is mm

Inventor doesn't forget the units.

I am doing some experimenting, I suspect that you cannot use implied negative ^-1ul

[JDMather]

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@Anonymous wrote:

my equations are not dependent on units .... 

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R is in mm  You have R=100mm which you are then squaring
S1 is in mm You have S1=286.706mm which you are then squaring

L4 is mm

Inventor doesn't forget the units.

I am doing some experimenting, I suspect that you cannot use implied negative ^-1ul

[Anonymous]

ok thankyou i didnt see anything for squarroots so i just did that

[Anonymous · Accepted solution]

Dear sedwar22,

Putting a quantity to the negative first power divides one by the quantity.  x^-1 = 1/x

What you would want to do to take the square root in the parameters is use the sqrt() function.

You might also want to re-enter your argument and put parenthesis around the powers. sqrt((S1^2ul)-((2 ul*R)^2))

[Anonymous]

whoops i meant to have it to the power of 1/2 lol but yes i have tried putting the powers in () but thanks for the sqrt function i didnt know it was used here since i didn't see it on the list of commands i could use. but thanks i will give it a go