I am programming the SES Arm with a my program to do precise movements of the arm on a plane. I tried in many ways, but the arm seems to follow a non stable trajectory. For example, on a XZ plane (i.e. like the ground), the arm precision is almost acceptable, but on a YZ plane (i.e. like a side wall) the arm vibrates too much and tends to go down when I try to put the arm at 90 degrees and move it forward.
Can anyone help me with this problem? Probably I made mistakes when I build the arm or the arm itself can’t move precisely on a specific point, but only approximatively?
You really need to specify the level precision you expect from the arm. You should understand the arms are hobby/educational devices and are not really designed for a high level of precision.
Hi,
I tried with springs, but the result is still the same. I have big problems to stable the arm in a certain position, because it tends to vibrate while moving. Moreover, sometimes it tends to block a bit while continuing a trajectory. I mean, for example, moving from one point to another point: the arm starts to move, then, sometimes, it blocks for some instants in a position, and then continues to move until to reach the final position.
I need a good precision of the arm, maybe there is another arm of Lynxmotion with better precision and stability? Or maybe I made some mistakes on the arm building?
Until we make a pivot with mechanical dampening, (it’s being done right now) there will be some issues with finding the correct speed of motion for the servos being used and the mass of the arm and it’s payload. Too slow and it can move in waves, too fast and it can have overshoot problems. The ball bearings while extremely low friction offer no dampening. If this is the problem help is on the way.
Hi, first of all, thanks for the response.
Yes, the problem is exactly this, so what can I do for now? Can I simulate, in some way, this pivot at software level? Or I need an hardware pivot to correct this?
Thanks in advance.
I am having a special “bearing” injection molded, that encapsulates one side of the end of the “C” bracket. This will replace the ball bearing, and as I said add mechanical dampening. There has to be lots of other ways to do this, but I don’t know your skill level for making modifications or custom parts. The idea is to add a precise amount of, hate to say it but “friction” to the axis effected by the problem.
BTW if we could get servos with more gear reduction it would not be a problem.
Hi, I didn’t understand very well what you exactly mean. Maybe you mean that I can put a kind of bearing, like the two hubs used in the wrist rotate assembly, at the sides of each junction to add friction?
Thanks in advance.
That’s the idea. By attaching the two plates you make a 3mm hole where the 8mm hole is. It aligns with the hole in the ASB-04. By adjusting the tension of the hardware you can adjust the dampening.
