I’m looking at making an arm that can lift around 2kg. A while ago I thought this would be too hard, but I have a few ideas.
I was wondering a few things though.
First, I need a gripper that can carry this load, so I thought I’d ask if the little gripper would be able to? It doesn’t look strong enough. Also, how long is it from the wrist joint to the end of the gripper?
Second, How strong is the alluminium tube? I don’t have any yet, and was not sure if it will be able to handle the load?
Third, I was wondering how strong the low profile axis is? If this were used for the gripper, do you think it would be strong enough?
I doubt that the lynxmotion arms are really suitable for manipulating a 2kg object (I don’t own any of the arms, so somebody that owns the arms may have better info). You probably need to get an industrial grade arm, or custom make an arm that is more suitable for the specific functions needed from the arm.
Would be helpful to know the rough distances involved in the arm you want to make as that will drive the torque requirements. they also let you figure out how much the tube will bend under load. if you can get servos to do the job (torque question) then you just want to make sure the error introduced by your mecahanicals doesn’t approach that of the positional error of the servos.
just rough numbers to ponder, the hsr-5990tg is rated 417 oz-in at 7.4V. 2Kg is about 70 oz. so even if your arm weighed nothing, one of the best standard form factor servos could only lift 2Kg at about 6" (15cm).
I think I will have to use different materials for the arm and gripper, but I thought I’d ask.
I would like a reasonable length (40~45cm I guess).
The idea was to use these SPT400 systems:
If I put a HSR-5990TG in there, in theory I should be able to get over 2,000 oz-in of torque (time and money will tell). I haven’t figured out how I would mount them yet, but I think I could rig something up.
Eddie, you do raise a good question about error. They do say the pots used are high quality, but I guess I wouldn’t know about the error untill I tested it. Also, I will need some pretty strong material for between joints.
Has anyone else used these before?
I may have got a little carried away with 2kg, but I think 1.5 shouldn’t be out of the question assuming the error in the servo system and flex in the material isn’t too bad.
And, yes I have accepted that this will probably not be the most accurate arm in terms of positioning.
These offer 135degrees of tilt, which should be plenty. I would like to be able to have full extension, and have the gripper reach back nearly to the base of the arm. I have a pan system in mind too, made by the same people.
The gripper doesn’t need to be really accurate as this will most likely be used via remote control and not with programed sequences. Also I expect to only need to lift items that are easy to hold.
The speed is also not extremely important, however, it would be nice to be as fast as possible. According to the table they give, it will be about 0.7s/60degrees, although I expect a fair bit higher when loaded up.
Bear in mind, this is just for hobby use and it will be experimental. I just wanted an arm that could lift a decent weight. I know it’s the wrong way around, but I will make my application fit my design.
I haven’t got anywhere yet. At this point I am just gathering information. I’m not going to start spending lots of money until I start work (I finish my uni degree early November and have a job to start right away).
I think I will source some Al tube with a slightly larger diameter as I have access to the tools I will need to machine it. Thanks for the idea though, I will consider it more if the Al doesn’t work out.
I will keep you informed when I start. Thanks for the interest.
