Vex Stair Climber

Hi, im trying to build a robot that uses tri wheels to climb stairs,
I have one built, and from the parts i have, i thing it is the only one i can build…:frowning:
Anywho, does any one have advice on how to mount this single wheel system to climb stairs, while still be able to drive normally

here are the pictures

A Tri-Wheel support system?? Excellent!!!

The stairs would need to be no higher than the Center of the Tri-Wheels, causing them Roll Over to the next step.

You will need to get an additional Wheel Kit, and use the 4" or 5" Wheels.

Close Up

i was thinking you could use the “drill through the gear” method used by another stair climber and use an 84-tooth gear with standoffs to rotate the tri-wheels.
First version with triwheels
some sucess, could go over binders and stuff
second version with triwheels, total failure, didnt do anything right accept turn really well
redesign due to lack of pieces for second triwheel:(
mostly failure, sorta worked, but only on chance
finally some sucess:eek: , does not climb on conventional stairs yet, but will go over longer plat forms

If anyone has any comments on how to make something that will go over conventional 12 inch stairs, please help

appreciate it:)
This robot will climb multiple steps
I climbed this mock set up (yeah vex box)

still have some problems

  1. limited by length of stair ie. the stair must be around 14 inches long
    2.the driving feels awkward, would really like to program it, but i havent bought the kit yet (still saving for it)

anywho… first taste of sucess…killer
if you have any suggestions or comments plese post

the programming kit is probably your second most important part for making robots, the first being the starter kit. why? the kit allows you to make your own controls for the robot, or things like autonomous robot. wouldn’t it be cool to have a robot that can navigate a maze- by itself? with some ultrasounds and the kit, you could do that; or even without sensors if you know the maze you can make it so you start it up and it goes through the whole thing.

programming can also be used for hybrid control; say you want to make a robot that can drive around but has a complicated action t perform, like taking in yellow tennis balls but not ones painted black. you could have the robot drive around by remote control yet using ultrasonic sensors tell when an object is near and color sensors to decide if its worth picking up, then automatically scooping it up. this would save time in a competition.

‘real’ robots are autonomous, which of course needs programming. save up for the kit and buy nothing else. also, go with the easyc kit first; its great for beginners. HOWEVER, if you are a good programmer (e.g. have taken c classes, know some binary) and your really sure your advanced, buy mplab as it can edit all of the controller down to the nitty-gritty.

just my 2 cents.

if you want to do autonomous programming (a robot that makes decisions on its own) sensors are a must.

ultrasonics tell distance using high frequency sound waves, so you can essentially tell how far away you are from something, such as a wall. great for maze navigating, etc. 1 ultrasonic is pretty much just used like a bumper sensor, however, multiple ultrasonics grouped in different directions allows a robot to “learn” its surrondings.

light sensors tell light from dark using a photocell. it can see different values of light in a well lit room.

line trackers are the ‘advanced’ light sensors. they shine a non-visible infra red light on the ground, and can tell differences in black and white values on the ground. unlike light sensors, these can see different shades of grey in the dark! go into a completely unlit room and it can see black vs. white. one disadvantage, however, is that if there are infra red lights nearby interference can happen.

optical shaft encoders are life-savers for the autonomous programmer. they allow you to detected position and direction of motors; however without easy pro or mplab/robotc, you won’t be able to detect one of the values as easy c 2.0 can’t read interrupts. lets say you have a motor thats been through wear and tear, with a worn out low friction wheel, and you have a brand new wheel, axle, and motor on the other side of the robot. your robot won’t drive straight due to one side being stronger. you can fix this by adding this sensor. with this sensor, you’ll be able to make a formula to balance out the wheels’ speeds.

potentiometers are the ‘servos’ of optical shafts and itself. it allows you to see the angle of a shaft in 90 degree intervals, and sends only one signal to the controller in an analog form. pots are better for arms and closing/opening mechanisms whereas shaft encoders are better for constantly turning mechanisms like intakes and drive trains.

i know im getting a little off-topic from the thread- sorry lol

bloodsheddragon, when you said “it allows you to see the angle of a shaft in 90 degree intervals, and sends only one signal to the controller in an analog form”, don’t you mean digital form? analog sensors read in a range, say, from 1 to 360. digital just read 0 or 1. unless you meant something else

It is analog. The potentiometer can measure up to about 250 degrees, which varies the analog port reading from near 0 to near 1023. So in theory, you get around 0.25 degree resolution. In practice, I don’t think you’d get that much resolution because of electrical noise, non-linearity, mechanical slop, etc.

Details are here

BTW - I think the 90 degree number actually refers to the amount of adjustment available in the mounting slots on the body of the potentiometer.


  • Dean

i misexplained, by 90 degrees i meant 1-90 degrees; though quazars comment corrects me.

but yes, if it was 90 degree intervals like i said, you would be correct.

ill get on buying that programming kit
I have a basic understaning of programming; made a marble sorter with fisher technic, prolly get easyc

here’s a video of the robot working…

any one have a suggestion on how to lessen the step length limitation, i’m kinda stuck

you could use a linear slide with a rack and pinion set up to achieve this, you could also have an ultrasonic sensor to see how tall the step is then adjust as required

look at these vex products: Rack and Pinion Gears Linear Slide Pack
[ Ultrasonic Sensor

oh and for this setup you will need a couple extra motors]( Ultrasonic Sensor)

Rack and Pinion Gears Linear Slide Pack
[ Ultrasonic Sensor

oh and for this setup you will need a couple extra motors]( Ultrasonic Sensor)

I absolutely agree with basicxman except I do not know if the linear slide rails can support the weight of the robot. If you weigh the robot and then post that I am sure someone can tell you if the slides can support it. Also I noticed that you have burlap on your tank treads. What is that for?

i beleive that’s for grip, i think it’s that material that fruit sometimes is wrapped on, it’s kinda sticky in a way but i really grips to smooth surfaces