Help Building A Mobile Robotic Arm

[K-Squatch]

I have no previous experience working with robotics, but my teacher sent me and a few classmates a challenge. We're to build a robotic arm that's able to move freely around a room, the arm as well must reach at least 2 feet high and 3 feet long. I was wondering if anyone knew of an adequate tutorial, or were willing to teach me some of the basics as I'm not even sure where to start. I have done a fair amount of research to this date, but I don't quite think it's cutting it. On a side note the robot must be made from scratch, so building from a kit is sadly not an option. As for money, the school is budgeting a decent amount of money so it can't be anything to overly expensive, but it doesn't have to be cheap. Any help would be greatly appreciated as I'm very interested in this field and a help with the first step would be wonderful.

[cooldog]

you could use the $50 robot boared to control it
http://www.societyofrobots.com/step_by_step_robot.shtml

you could use a basic 2 wheel and caster chasi to drive it around or a four wheel desigh using 4 servos and 2 y-harnesses
http://www.societyofrobots.com/mechanics_chassisconstruction.shtml

for the arm you will need strong servo's for motors to contol it.
-if your using motors:
http://www.societyofrobots.com/schematics_h-bridgedes.shtml

how many joints do you want?
http://www.societyofrobots.com/robot_arm_calculator.shtml
http://www.societyofrobots.com/RMF_calculator.shtml

some ideas
http://www.societyofrobots.com/robot_ERP.shtml
http://www.societyofrobots.com/robot_arm_card_dealer.shtml
http://www.societyofrobots.com/robot_arm_tutorial.shtml
http://www.societyofrobots.com/robot_asme.shtml


notes:
the $50 robot boared can handle 5 servos/motors so you can use 2 for driving but you are limited to 3 for the arm...  you could do a turning base for it, a shoulder and a hand, before you would want to upgrade the microcontroller to more servo/motor ports maybe the axon or the roboduino

[Razor Concepts]

The $50 board can handle as many servos/motors as many output pins it has.

[K-Squatch]

Thank you very much, I'll talk to my group about it. As for amount of joints I was probably looking for 2 not including the "hand" per se

[Soeren]

Hi,

[...] or were willing to teach me some of the basics as I'm not even sure where to start.

Your avatar suggests that you're in Denmark (as is I), but where in DK?

[K-Squatch]

I actually live in Canada, I'm just from Denmark myself. I have to have some pride don't I? =]

[Admin]

the arm as well must reach at least 2 feet high and 3 feet long

How much weight does it need to lift at this extension? Sounds like you will need a motor with a worm gear box.

and yet even more links for reading material . . .

http://www.societyofrobots.com/mechanics_FEA.shtml (for stress analysis)
http://www.societyofrobots.com/mechanics_statics.shtml
http://www.societyofrobots.com/mechanics_gears.shtml (to calculate your gearing ratios)

[K-Squatch]

We're probably only going to be lifting something simple like one tennis ball at a time. This project is seeming harder then I thought it would be. Is there any specific order I should do any of this in?

[cooldog]

always start with the design use a program like google sketch-up

[K-Squatch]

I've started the design. Is it possible to get differential drive with only using one channel?

[SmAsH]

no probibly not, as you would need to control both motors separately.

[cooldog]

you an have two servos on one joystick but u need two channels

[K-Squatch]

And a normal robotic arm has four channels correct? Like for a rather simple one.

[cooldog]

ya

• rotating base
• shoulder
• wrist
• gripper

[K-Squatch]

Does anyone possibly have the schematics for one, or are willing to help me create some? Because I'm rather confused on it.

[cooldog]

what part confuses you

[K-Squatch]

I'm just daunted by the entire task. lol. But thank you for the help, we'll see what we can make up.