# 6 DOF Robotic Arm (A.R.M.)

Hi

I'm currently building a robotic arm as a graduation project, which I named A.R.M. (Articulated Robotic Manipulator).

I would like to add that I'm following some courses about inverse kinematics and basic programming at the moment.

Some specifications:

- 6 DOF

- Reach: 1 m

- Power source: 48-55V DC

- Budget: +- €1500

Progress:

The mechanical design is completed and the robot is being built at the moment.

I've ordered the drives and I'll be buying an arduino soon.

Problems:

• I've calculated the needed torque for each motor (stepper motors will be used) via static calculation. This had to be done fast, so I've used big margins. Still, I would like a dynamic calculation to add to my thesis. If anyone has tips for this, help is much appreciated! On the Internet I often find static calculations, and I'm wondering if anyone bothers to do a dynamic calculation? I also didn't find dynamic calculators, where there is an abundancy of static calculators (some better than others).
• I'm looking for a cheap gripper of other actuator, but this seems to be harder than I thought..
• I'm wondering what the next steps are, since this is my first project.

Kind regards

Matthieu

## Comment viewing options

I like the name.  Just the sort of thing I like!

This is a cool project.  It's a bit adventurous for a first go.  With the budget you've set it should be within reach, though.

I think I understand what you mean by "dynamic calculation" but could you elaborate so that I and everyone else is certain?

You are going to need some REALLY big steppers.  As you probably already know, you are going to need about 20 N m of torque just to hold it in place ( I suspect this is your "static calculation") and more to move it ("dynamic calculation.") And don't forget the mass of the arm itself.  I'm not sure I've ever seen steppers that big.  Certainly not on the hobby market.  You will probably have to go to an industrial supplier and pay big money.  And of course they will need really big drivers, which means a lot more money.  I would recommend that you consider DC gearmotors with encoders of some sort.

As for grippers, there aren't many that are cheap and certainly not cheap that can lift 2 kg.  You might consider this one http://store.makeblock.com/robot-gripper from Makeblock.  It comes pretty close and is pretty cheap.  It's fairly well made for the price.  If nothing else you can use it as a pattern to build your own.\

EDIT:  Here's one supplier of steppers.  Looks like about \$300 to \$800 each for what you would need.  Not counting a driver.

The dynamic calculation is the calculation of the needed torque when the different parts of the robotrobot are moving. That's where I'm stuck at the moment. A couple of years ago I've learned how to do it by hand, but simulation software of some sort would certainly make my life a bit easier!

I've already bought the steppers and drivers. I'm using gearboxes to reduce the needed torque.. The robot will not be fast, but when there is a bigger budget (maybe next year) they could use industrial servo motors. My supervisors (don't know if this is the correct word) said my static analysis is alright, so I hope I don't run into any surprises.

The gripper is only for testing, so it doesn't need to be able to lift/hold 2 kg.

And last: if someone has an 'easy' method of working out the inverse kinematics, please feel free to share it!