Robot arm on mobile robot

[megaman935]

  :POk, so my little brother has muscular dystrophy- but hes not in a wheelchair- and he has problems bending over. So, I'd like to build a robot that can pick somethin up and possibly give it to him. I saw the tutorial for the robot that climbs walls, is there a way 2 do that by raisng or turning the robot arm more freely?

[Admin]

ok so no one has answered this yet, so ill give a crack at it . . .

first question, how would your brother control such a robot?

second question, pick up what? size/shape/weight are really important to consider

I saw the tutorial for the robot that climbs walls, is there a way 2 do that by raisng or turning the robot arm more freely?

do you mean something like this?
http://www.societyofrobots.com/images/robot_arm_mobipulator.jpg

[megaman935]

I'd like it to be remote controlled.. Pick up anything from a gameboy to a pencil... and yeah something like that. thanks for replying admin.
 

[Admin]

yeap, definitely sounds doable.

i think the hardest part would be programming the arm kinematics to work with your remote.

this might be a little overwhelming at first look:
http://www.societyofrobots.com/robot_arm_tutorial.shtml#forward_kinematics

if you build a 2 DOF arm, you can just copy my equations.

basically attach the remote control reciever to a microcontroller, then the microcontroller does some processing and outputs the robot arm commands.

there is also a lot of research going on with robot arms that feed handicapped people, might be worth looking in to. (cant think of links to suggest at the moment . . .)

[ed1380]

<---noob

I think something like this would make controling it easier than having buttons and joysticks on a remote. but after some practice i but those would work good too.

[JesseWelling]

I think that you would essentialy double your production cost though.

[megaman935]

Is it possible to do it without a remote controller? if so, what would be a good microcontroller to get for it on a 2 dof arm? this maybe?

http://cgi.ebay.com/myAVR-Board-USB-for-AVR-Atmel-Microcontroller_W0QQitemZ230091288469QQihZ013Q
QcategoryZ36323QQrdZ1QQcmdZViewItem

and how would you program it? I understand how differential drive works, but what would you use on a robot with 4 wheels? ...

[Admin]

if it isnt remote control, then how would it know when to pick something up? how would it know what to pick up?

[ed1380]

I robot with 4 wheels can still be deferential drive, just there will be a good bit of friction. like a skid steer loader (aka Bobcat), if you drive them on the grass it will tear up your lawn.

i agree with admin. maybe there is a way you could steer it in the general direction, and it would use sensors to automatically pick it up and hand it to you.

[megaman935]

 So it does need to be controlled... and that tutorial is very confusing... I have a 120 in my adv. math class but thats 7th grade..... in other words I havent taken algebra or triginometry...

[ed1380]

enjoy childhood while you can. forget advanced stuff, just have fun. when you turn 15 and have taken the requiered math courses retry it.

[Admin]

i would say the most important 'advanced' math you will ever learn and need for robotics is algebra

the second most important is trig, and the third most is calculus.

study up! it'll pay off in the long term.

[ComputerGeek]

This is my first post but I hope to make some great contributions to this site.

Getting back on topic, as cool as the pic by ed1380 is, it's impractical if your bro has MD. You'll want something with a controlled speed to prevent overshoot; I would recommend a low frequency pulse generator (the legendary 555 timer IC is ideal) tied to an H-bridge, running what's called a stepper motor (I don't mean to patronize). The stepper motor will only move a few degrees per pulse from the timer who's frequency can be easily altered if using the 555 and a varistor; this will allow for changes in speed to be done quick and easy. As for the RC part there are kits available but they're over priced, just buy a cheap RC car <$20 and modify as necessary. This design is pretty modular so you can plug the concept into almost any project. If you need help attaching the microcontroller to the 555 say so in a reply otherwise it leaves a design challenge for some one who has nearly twice the math score I did at that age (I blame my ADHD  ).