Please suggest sources for: Motors & Controlers (for Robot Arm to lift 10-lbs)

[Mel_3]

We want to build a rather large Robot Arm... that can lift up to ten pounds.

I've Googled but maybe someone here will help us get to the right Vendors and/or Sources for...

- Motors & Controllers (Stepper or Servo as you think we need)
- Please suggest a type and model if you wish... that would also be very helpful
- And, do these controllers normally come with a serial or parallel interface that we can just connect to a PC?
- Or must we buy that seperately
- Or must we build our own?

Thanks for the help everybody and thanks for allowing me to put up a flurry of post till I get up to speed

[MaltiK]

Hitec HS-475 servo motors for the arm, an HS-422 for the base, and HS-85 and an HS-81 is for the gripper is a good idea because each have decent torque and arent too heavy

[ArcMan]

There's no way hobby servos can move 10 lbs. at the end effector, unless the arms were only 1" long.

Let's assume that the arm linkages are 12" long.  That's about 10 ft-lbs of torque at the first major joint and 20 ft-lbs at the base joint (when the arm is in the worst case position).  That equates to about 3,840 oz-in of torque.  Compare that to a torque in the range of 100 oz-in for a typical hobby servo.

Your going to need some monster (industrial) servos to move around that kind of weight.

[Mel_3]

Thanks for responding.

It's true we are going to need some large motors for this project. The robot arm will probably be 3 to 4 feet tall and with a long reach.

We may build a half size model first to demo the concept.

We are looking for used industrial robots but most are too expensive so now we are looking for junk parts that we can kludge together

Ten pounds may be a dream to be realized later. One to five pounds may be more realistic for now... maybe even one to three pounds... we just have to see what parts we can come up with.

I'm going to repost asking for sources for junk industrial motors, controllers, and parts as that thread may hi-light the issue more clearly and may be helpful to others.

Thanks for the help.

[Mel_3]

I'm starting a new thread on this as this question is more specific and may be helpful to others.

We are looking for industrial size motors, controllers, and parts for our large robot arm project.

Thanks to anyone who suggest possible sources... including dealers, repair facilities, or some used or broken equipment we may find and dismantle to salvage some of the parts.

[ArcMan]

I know you're trying to do this cheap.  If I were going to build a large robot arm on the cheap, I would use wheelchair motors and add encoders for position and velocity feedback.  The wheelchair motor outputs could be geared down to provide massive amounts of torque.

Now to do something big and cheap you need to be able to cut, weld and machine large parts (probably steel and/or aluminum).  You need to do stuff like cut keyways in 3/4" shafts and large metal gears.  Hopefully you have these capabilities.

[Mel_3]

Arcman,

Thanks for the note.

- We can handle the mechanical.
- We can also design and build our own controller boards if we have enough info on the motors.
- We will be writing our own software for this project.

I was just wondering today what motors we may scavenge and from what things.

Wheel chair motors are a good suggestion and we will check out local electric wheel chair businesses to see if the ever scrap a chair or the motor.

Please suggest any other devices we may look for that may have motors we can use.

Maybe electric trolling motors? Wonder if they are big enough?

Would also be nice to find some source for stepper motors... so if you know any equipment that uses larger steppers let me know.

Thanks again for the help.

[SciTech02]

I know a little about electric vehicles (people in that field always look for salvageable parts) and those vehicles require very large (6-9 in diameter) motors, so here is some advice:

Personally, I have never seen stepper motors in the size range you're suggesting.  If they do exist, they probably would be very expensive.  Fortunately, DC motors in that size range are relatively commonplace.  In my opinion, the best place to get motors of that size is *drumroll*... treadmills.  Yes, workout equipment like treadmills are common, easy/cheap to get and have good motors.  You may even be able to use the controll panel componets as the speed controller (or just use it as a speed controller).  Treadmill motors are usually DC motors, so you can build speed controllers for them (you can buy controllers for a good price on eBay).  You might, or have to, gear them to get the torque you're asking (I don't know for sure).

Hope this helps. 

[ArcMan]

Good idea.  Treadmill motors have lots of torque.

Hey Mel, keep us apprised of your progress.  I like to hear about big robots.  They have their own set of challenges.

[Mel_3]

Thanks for the help guys.

I went out today and started looking for electric trolling motors.

I'll start checking on motors from treadmills... but they are probably AC motors... right?

Keep the coments and ideas coming.

Thanks again to everybody.

[Admin]

http://www.societyofrobots.com/robot_faq.shtml#robot_arm

[jamort]

you could use pneumatics.... not as much control as far as where the arm stops but your goping to have a challenge building I would suggest looking into what FIRST robots are made of last year the could lift 10 pound balls