Author Topic: Suspension for soil transportation system  (Read 611 times)

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Offline UMaine StudentTopic starter

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Suspension for soil transportation system
« on: November 02, 2011, 09:41:36 PM »
I am a Junior at the University of Maine in the Civil Engineering program; for one of my classes we were tasked to pitch an idea.  My idea is for a new way to transport soil samples from the field to the lab.  The current transportation method is to merely store the samples in a stuffed cardboard box.  Consequently, the soil samples feel every bump and jolt that a passenger in the car would. Those movements cause the soil to compact, distorting the test data.  The concept I am thinking about is to create a system where the soil cylinder is placed in a container that is supported by a suspension system, so that bumps on the road are absorbed by the suspension, and the soil samples are left intact. 

I am wondering if the single part suspension that was created for robots would also be able to work for my idea.  The cylinders can get as large as 37" long by 5" in diameter.  Any comments of if the suspension design would work for this scenario or suggestions of another system that would work would be greatly appreciated?  Also, what would an estimated cost be for all the parts needed to create the suspension system?

Thank you are greatly.

Offline Soeren

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Re: Suspension for soil transportation system
« Reply #1 on: November 02, 2011, 10:28:38 PM »
I am a Junior at the University of Maine in the Civil Engineering program; for one of my classes we were tasked to pitch an idea.  My idea is for a new way to transport soil samples from the field to the lab.  The current transportation method is to merely store the samples in a stuffed cardboard box.  Consequently, the soil samples feel every bump and jolt that a passenger in the car would. Those movements cause the soil to compact, distorting the test data.  The concept I am thinking about is to create a system where the soil cylinder is placed in a container that is supported by a suspension system, so that bumps on the road are absorbed by the suspension, and the soil samples are left intact. 

I am wondering if the single part suspension that was created for robots would also be able to work for my idea.  The cylinders can get as large as 37" long by 5" in diameter.  Any comments of if the suspension design would work for this scenario or suggestions of another system that would work would be greatly appreciated?  Also, what would an estimated cost be for all the parts needed to create the suspension system?
I am wondering exactly when it changed... See, in times long forgotten, students were supposed to do their own work *gasp-horror*

You might take a look at how studio microphones are suspended and scale up accordingly - if it's good enough for studio work, your dirt should be fine.
No matter what (passive and dampener-less) suspension you use, there will be some change over long distances, but then again, just taking the dirt samples will have changed them.


Thank you are greatly.
Greatly what ???
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

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Re: Suspension for soil transportation system
« Reply #2 on: November 03, 2011, 12:43:28 AM »
Soeren, I think he's just looking for direction. He's probably a soil mechanics or agricultural or geo-related student, so it's understandable to require technical engineering advice.

UMaine, the issue with suspension systems is that they are dependent on two things: the frequency of the vibration, and the mass that needs to be suspended. If you know both, and neither will ever change, you can build a 'perfect' suspension for it.

But lets say one day you want a full box (20 pounds) and the next day you just want half a box (10 pounds). The suspension can't be optimized for both. You could say determine the 'average' amount of dirt for a box, say 15 pounds, and design for that as 'close enough'. In this case, the suspension will be a little too rigid for 10 pounds and too bouncy for 20 pounds - but it still might be 'good enough' depending on how picky you are.

For SoR single-part suspension (which you saw on my ERP robot wheels), the robot weight was well known and not changing, and the frequency was very low.

If you want something 'quick and cheap', I'd recommend it to you. It's only one part from a single sheet of plastic or metal, so very cheap. However you'll need stress analysis software (such as ANSYS) to design it properly, and good machining skills (I used a CNC). I'm a mechanical engineer so I know how to do the calculations . . . if you can find one to join your team, you can have him do it for you.

If you don't have either capability, or an engineer, I suggest making about ~6 different prototypes of similar design but different beam thicknesses using your intuition. Try each one to see how well it works out. You want it to flex and bounce. If it's too flexible, it'll sag under the weight. Not flexible enough (ie rigid), then there will be no suspension.

Another idea would be to design a system that suspends the box using a system of springs. Buy about 10 different types of springs of different k (strength of the spring) values, and try each to see which works best.

hope that helps . . .

 


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