OptimumK

[ben]

As I understand it many teams are using OptimumK for their kinematics anaylsis. I'd be interested in any feedback relative to the other programs that are widely used (WinGEO, SusProg, etc), any tips, tricks and general experiences.

So far I'm pretty happy with it, but I'd be interested in some feedback from more experienced users.

Regards,

Ben

[ben]

As I understand it many teams are using OptimumK for their kinematics anaylsis. I'd be interested in any feedback relative to the other programs that are widely used (WinGEO, SusProg, etc), any tips, tricks and general experiences.

So far I'm pretty happy with it, but I'd be interested in some feedback from more experienced users.

Regards,

Ben

[Chris Lane]

I used Optimum K extensively for our first car which has just finished competing.

It is a great piece of software; hugely powerful in analysing existing systems (ie. built cars if you can measure them up quite accurately), and great at simulating a system undergoing design.

The only thing I found you need to do is run a CAD model of the car/suspension in parallel to this software, so you can identify packaging/interference problems as they develop.

But otherwise very user friendly, easy to manipulate, excellent support from Optimum G, and highly adaptable. Well worth the asking price!

[Crispy]

Do you know if there is a simple way of importing and exporting suspension geometry between Optimum K and a CAD package?

Thanks

[Chris Lane]

In a direct fashion, I don't think so.

You can however export an excel spreadsheet of all your points in space, so you can just plug them in to Solidworks as XYZ coordinates.

[Zac]

How well does it work for linkage synthesis? ie. if I want to model a suspension based on known curves or data from a K&C rig.

[Chris Lane]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Zac:
How well does it work for linkage synthesis? ie. if I want to model a suspension based on known curves or data from a K&C rig. </div></BLOCKQUOTE>

Optimum K is an analysis package, not a suspension design package. It will not automatically determine anything for you.

You can however import Motec data to simulate a track environment. Haven't tried it yet though as it is a new feature.

[Tim.Wright]

Hey Ben,

I did a back to back analysis of OptimumK and Susprog3D during my thesis year last year, so I'll weigh in here a little.

What I found was exactly as Chris said, OptimumK is extremely powerful at analysis but you need the design first. After using both pretty intensively last year I ended up using both programs in the following fashion;

I used Susprog to do the actual design. OptimumK is pretty limited in this respect (the version I was using anyway). With susprog you can set RC heights (or not), define bellcrank geometry in their own co-ord systems (allowing easy change of shock or pushrod lever arm lengths), same with uprights - they have their own axis system. There are a number of approaches you can use define the points based on what you want Susprog to calculate and what you want to set yourself. It can calculate your inboard or outboard steering/toe pickups to reduce bumpsteer to zero, calculate driveshaft plunge etc etc etc... Heaps more too, so in terms of design I found that it wins hands down.

The down side is that it is quite hard to learn and get a handle on. There are still some parameters I don't understand or use, but to me thats a positive. Still more for me to explore.

Where it is terribly let down though is on the analysis side. The visualisation is clunky and you can't see both side of the car moving together (in my verison anyway - few years old now). You can't program combined movements into its kinematic model, and its steering analysis is very limited. No graphs, no import of track data and no overlay/back to back comparison of two separate designs.The worst part of Susprog is that you can't simulate roll AND steering together which is hopeless (how often do you get roll and no steering!?).

These are all areas where OptimumK excels at. So combined steering/roll was the first motion I used to analyse after I set the design in Susprog and 'ported' it across to OptimumK. I used and analysed heaps of graphs from OptimumK to get roll centers at the front and rear somewhat well behaved and moving in tandem and was able to better monitor KPI trails and offsets better in OptimumK.

So in short, OptimumK (I found) is pretty much restricted to analysis, but I was promised a lot of extras to rival Susprog3D etc in the future when I emailed somone at OptimumG.

So I think OptimumK would be a good tool in the future but is a bit restricted right now. Anyone correct me if I'm wrong now as this was just over a year ago now. I was using OptimumK V1.0 ans Susprog ~4.5 from memory.

Zac - in response to your question, I can't think of an easy way to reverse engineer a double wishbone suspension setup based on K&C data (is that what you are asking?). I would do it incrementally in susprog using numbers like camber gain to drive the VSA lengths to start with. But for a given set of K&C data there would be an infinate number of ways to achive that with a double wishbone setup.

Sorry for the epic, but I thought since I'd trialled and benchmarked OptimumK pretty extensively I'd put my $0.02AUD in.

Tim Wright
EX Curtin Uni
Suspension & Vehicle Dynamics

[Chris Lane]

Have you seen the exchange rates at the moment? Your AU$0.02 is worth, like, nothing! http://fsae.com/groupee_common/emoticons/icon_razz.gif

Optimum K 1.1 was released a while ago, and sports some interesting new features. I haven't explored any of them yet however....

[Zac]

Tim, that's exactly what I was getting at. I know it's not an easy thing to do (I think lotus spent a lot of time + $$$ developing something like this). In my case I'm not looking for an absolute suspension design, but rather something I can use to fill in holes and smooth out edges in my data.

[ben]

Great post Timo. Having seen what's coming in newer editions of OptimumK I'm quite happy - particularly force based roll centres with a tyre model.

I guess it depends on how you do the design. I'd do a 2D CATIA sketch to define a baseline toelink position and move the pick up around to see how close you can get - these suspensions are fairly linear around a sensible level of wheel travel and once you factor in compliance and tyre deflection is anything more complex necessary?

I am slightly biased in that I'm using it to analyse suspension systems that already exist - and you do point out that it is better for that than most of the other packages.

Ben