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MarkJC
10-26-2009, 01:02 AM
I'm working on a project that involves moving small weights at the bottom of a stairway to the top stair using some remote controlled mechanism. Each stair is 1-ft tall, and i'm limited to a 1-ft height starting dimension for the entire device. Building an actual stair climbing robot that can accomplish this task is out of my league, so i'm looking at various methods of extension involving possibly a crane system or a track extension up the stairway to accomplish the task.

So far, possible methods of extension i've come across are telescoping and scissor jack styles of extension, but both of these seem impractical. Of the telescopic cylinders i've run across, hydraulic and pneumatic, both types seem very expensive and difficult to acquire, and few small scale ones exist.

I was wondering if anyone else had some suggestions on other possible extension methods that might be applicable to this project, or any other low cost alternatives? I'm pretty stumped on how to proceed with this challenge.

ooops
10-26-2009, 09:19 AM
You really haven't shared enough detail on your project to make suggestions. How many steps? What is the length of the tread on the step? How many weights and how much do they weigh?
My first impression is make a "grasshopper". Something that can "jump" up the stairs.
Maybe better yet a gymnast-bot that can flip up the stairs. Basically, an arm to grab the above tread, and a motorized pivot point to rotate the rest of the bot up and around.
Share more details and I am sure you will hear some better ideas.

sam
10-26-2009, 09:36 AM
I was thinking of a wheeled bot that could extend in two ways. Upwards and then towards the next stair. So it would lift it's COG upwards and then towards the next stair (above the next stair). Then lower the weight on the stair. All that would be left on the previous step would be the skeleton of the bot, which wouldn't weight to much and since most of the weight is on the next stair, the skeleton could be brought up to the next step and repeat the process...

At the end of this page their is the vex images of a linear slide that could maybe lift the bot if it's not too heavy. Four of these at each corner of something like that.

EDIT : Forgot the link lol :

MarkJC
10-26-2009, 11:22 PM
Sorry, I should have listed more of the details. I'd like to be able to transport each weight up at least two stairs. There is no tread on the steps, but they are wooden, so there should be a decent amount of traction. The stair dimensions are 12" high, 32" wide, 12" deep. These are some pretty big steps.

The weights weigh approximately 1lb, but I only need to carry one up at a time. I should add that I would need another mechanism for picking up the weights - they won't be firmly attached to the robot or device. I'm also limited to a \$150 budget - which I realize is not much for what is required.

The price is also one of the reasons i've been steering clear of a traditional stair climbing robot and looking into other methods of extension, perhaps involving a crane system or extendable track. Unfortunately, I continue to come up short in my search for low cost mechanisms to accomplish the large extensions that would be required in such a system..

10-27-2009, 12:28 AM
A triple drawer slide with a creative mechanism of driving the slide in the track should cost more than thirty or fourty dollars. The creative mechanism for driving the slide in the track I leave as an exercise for the interested engineering student. :)

darkback2
10-27-2009, 07:58 AM
Lets look at this from an end effector/cost perspective...

The robot can not be any taller than 1foot...

1) So the robot picks up a weight 1lb...which means some sort of gripper...arm thing...at least 2 degrees of freedom.

2) Then it has to extend up 1 foot? at least 1 dof

3) Then it has to move forward onto the step 1 dof

4) Then it has to retract and reset itself for the next run 1 dof for the extending legs? (I can't figure that one out.)

so that totals 4 if not 5 actuated dof 3 of which have to be strong enough to carry the entire weight of the robot, and 2 of which have to be able to carry the weights.

I would go with more of a scissor approach, and consider adding some sort of vacuum thing so that it can suck itself to the steps...so you have one segment that is standing up, and the other is flat on the step...then it drives forward, the standing up section sucks on to the step, and slides up, then pivots down to suck onto the top of the step...then it pulls forward?

I don't know...hope this helps.

DB

10-27-2009, 12:38 PM
Actually - I don't think most of the assumptions you've made are absolute against the competition that was described here.

At least in what I read - there is no gripper requirement, there is no move onto the step requirement, there is no requirement for "extending legs [???]"

darkback2
10-27-2009, 02:36 PM
Actually - I don't think most of the assumptions you've made are absolute against the competition that was described here.

At least in what I read - there is no gripper requirement, there is no move onto the step requirement, there is no requirement for "extending legs [???]"

Is this directed at me? cause I'm not sure I follow.

DB

10-27-2009, 02:54 PM
Yes - I'm not seeing any requirement in what was written for there to be a gripper, for there to be any requirement for the robot to physically move anywhere and no legged requirement.

darkback2
10-27-2009, 03:12 PM
Yes - I'm not seeing any requirement in what was written for there to be a gripper, for there to be any requirement for the robot to physically move anywhere and no legged requirement.

I thought the robot had to move the weights up the stairs, and Mark wanted to do it by making several trips...

10-27-2009, 03:14 PM
I don't see where it says the robot has to travel up the stairs. And Mark seems to be suggesting it doesn't where he writes:

steering clear of a traditional stair climbing robot and looking into other methods of extension, perhaps involving a crane system or extendable track.

darkback2
10-27-2009, 03:34 PM
that would be my mistake then...

10-27-2009, 03:47 PM
No Big. We're still not getting a good picture of the challenge, so it's all speculation, yours, mine, everyone's.

sam
10-27-2009, 05:04 PM
Haaaaa.... I understand now the crane part.

jes1510
10-27-2009, 08:11 PM
Personally I think a wall mounted carriage would be the best bet. A 1/4"-20 drive screw and a stepper motor could lift the carriage up and down the steps. The drawer slide linked above would work great for that. That is about the only way you are going to stay under the \$150 budget that I can think of.

Gorbag
10-27-2009, 09:09 PM
Explosions! Just fire the payload to the top stair.

MarkJC
10-27-2009, 11:21 PM
I don't see where it says the robot has to travel up the stairs. And Mark seems to be suggesting it doesn't.

Adrenalynn is correct that it doesn't have to be a stair climber. It can be pretty much anything, and i've toyed around with some pretty far fetched ideas as a result, like an RC helicopter. That was probably one of the simplest and most plausible solutions, but that flopped since I can only use standard nonrechargable 1.5V batteries to power the device.

The triple drawer slider is an interesting idea, but the real difficulty for me would be creating a mechanism to drive it. I don't believe that fabricating such a mechanism from the ground up is within my abilities, so I would probably need to search for something with a similar operation that is already fairly complete. Unfortunately, I also won't have a wall that I can mount anything on as jes1510 suggested.

I'm still hoping there is some unique, "outside the box" and relatively simple solution that i've so far managed to overlook.