Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

My Robotic Arm

Status
Not open for further replies.

baberjaved

New Member
Heres' a picture of my Robotic arm.. Comments Please! I Still have to make the software for it and the End Gripper is also under construction at the moment. =)
Can anyone tell me how can I find out exactly how much torque would be required at any joint of my arm and see if my Stepper motor can provide that much torque or not... Otherwise as the weight is quite a lot maybe I'll have to use some other motor (or maybe I can use Gears? If yes I dun know how :s)

**broken link removed**
 
Looks very nice! Let us know how it turns out! Also, please post schematics for your controller, and the software, if it is ok with you, of course.
 
hello,

Nice work.. however, if i was you, i would put all the motor in the base arm (the shoulder) and find out a way of transmitting power to the rest of the robot through wires. I did that last year, with bicycle brakes metallic wires, and it worked perfectly, we had a robot with movements controlled by 6 motors, and they were all in the base of the robot. This way you reduce inertia, also you need less power to move the 'end effector' of your arm.

good luck and keep us posted
 
ikalogic said:
hello,

Nice work.. however, if i was you, i would put all the motor in the base arm (the shoulder) and find out a way of transmitting power to the rest of the robot through wires. I did that last year, with bicycle brakes metallic wires, and it worked perfectly, we had a robot with movements controlled by 6 motors, and they were all in the base of the robot. This way you reduce inertia, also you need less power to move the 'end effector' of your arm.

good luck and keep us posted

Well I'm tryin to Run this thing now and The torque provided by the motor is way too less to lift the arm up...ikalogic your idea is very good and I would like to implement it in my arm but now that its already made I don't know how can I? =/

Anyideas to solve this torque issue? I need the motors to move this.. but the weight is just too much =/
 
baberjaved said:
Well I'm tryin to Run this thing now and The torque provided by the motor is way too less to lift the arm up...ikalogic your idea is very good and I would like to implement it in my arm but now that its already made I don't know how can I? =/

Anyideas to solve this torque issue? I need the motors to move this.. but the weight is just too much =/

From the look of it you're trying to use stepper motors at the joints?, there's no way you can ever make that work, stepper motors are weak to begin with, and you're gearing them up a lot and making them MUCH weaker.

I can only suggest you scrap it entirely and start again, this time give some thought how to make one - and test before you build it.
 
baberjaved said:
means there's no way I can add Gears and produce enough torque to make this thing work?
Sure why not, but you're going to have do some radical changes to make it work. Pulleys / chains might be the way to go, High torque motors for the heavy bits (steppers won't do it, not cheap ones anyway)
Counterbalancing goes along way too.
Here's the old Armdroid1
https://www.senster.com/alex_zivanovic/armdroid/index.htm
**broken link removed**
 
Nigel Goodwin said:
Like Bill says, you would need to rebuild it entirely - your existing model also looks incredibly heavy?.

The ARM itself is not that heavy but the motors are...
you mean One Motor cannot even lift the weight of the rest of the motors?
 
It's because it's a 3rd class lever, the fulcrum has to support the entire weight of the arm.
Take a yardstick and add a 1kg weight to the end and hold it out at arms length. Heavy isn't it. Welcome to physics 101.
**broken link removed**
**broken link removed**
 
blueroomelectronics said:
It's because it's a 3rd class lever, the fulcrum has to support the entire weight of the arm.
Take a yardstick and add a 1kg weight to the end and hold it out at arms length. Heavy isn't it. Welcome to physics 101.
**broken link removed**
**broken link removed**

A Class 1 fulcrum usually has a Mechanical advantage of less than 1, 1 exactly, or more than 1. A class 2 Has A MA of more than 1 Always or Exactly 1, but never less. A class 3 Lever has a MA of 1 or less, but never over 1.

Wow I actually did learn something in HS so far :)
 
baberjaved said:
The ARM itself is not that heavy but the motors are...
you mean One Motor cannot even lift the weight of the rest of the motors?

No, because (as Bill's diagrams show) they are at a massive mechanical disadvantage, and steppers are only low power anyway.
 
Nice solid construction! In fact, from the sounds of the other comments, too solid!

Firstly, torque = force * distance, force = mass * acceleration, acceleration = the change in position divided by the change in time.

So you could do some measurements to find out just what kind of torque you were looking at here.

Secondly, as has been suggested, you should looking to gears and chains. You could have all your motors at the base, and using a series of chains or even simple strings connected to winch type deals, really decrease the amount of weight you are dealing with.
 
A counterbalance would also help the main joint.
Notice how the motors (top) are an effort to balance the arm, the Hero1 arm could only lift (barely) 0.5kg
**broken link removed**
 
You need to reduce dead weight by all means.

you have to spend much more time designing your arm than constructing it, otherwise, believe me, you end up building a useless metallic piece of crap! This is a number 1 rule that we learn in engineering schools.

sorry for being so direct, but honestly, you have to!
 
Guys, do you have a circuit to control 3 unipolar stepper motor?. im using the printer port and 3 ULN2003a chips to interface the 3 motors. I'm new here, how can i post the pic of my robot arm, i already finish the arm but i need a controller. thanks
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top