Hey all i figured i would come here for some advice since iv seen so many other people get great help here on the forums.
I have 2 L6 arms, one i have purchased a while back and one that i got over the holiday season. I originally had done no tinkering with the arm till i got the second one because i would like to do something where they both work together.
Anyway here is where i encountered my first problem. The first arm was put together exactly per the instructions online. I double checked and re checked everything before i turned it on for the first time. So i go to turn it on launch up the software and click on the All 1.5 button to see that all the servos align like they should. Now imagine my surprise when the griper goes nutz and the motor just keeps spinning making a horrible noise clearly destroying the gears.
To make a long story short the instructions say to put the wrist rotate servo in channel 4 and the gripper servo in channel 5. I checked this about a thousand times and it was exactly like it was supposed to be. I could not understand what happened. until i went into the SSC-32 Tab to manually adjust the wrist rotate lvls and the gripper lvl, to find out that in fact channel 4 was controlling the gripper and channel 5 the wrist rotate.
This being opposite of what the instructions say. So for some reason my SSC-32 boards channel 4 and 5 are not controlling what they should be. I checked this with my other arm where i switched the gripper to channel 4 and the wrist rotate to channel 5 and it worked fine.
So i now have one arm where the gripper servo is completely useless and I’m pretty sure i wont be able to get a replacement from Lynxmotion just due to how long its been since i bought it.
My other problem was that i bought a metal base and put the other L6 arm onto it and have noticed that there is an abnormal amount of jerky movement coming from the base servo. When the arm is at a stand still but all the servos are engaged i can literately with my finer applying very little pressure jiggle the whole arm a little bit so that it creates this kind of jerk movement while standing still.
Dose this base require a different servo? I was under the impression that this base works with all the arms, but now looking back the only pictures i have seen of it are with the SES arm, and there is no description of what arms it works with on the website.
Any help is appreciated I’m a little bummed about the other arms gripper servo and what I’m going to do with it. I have no idea what would be making those two channels reversed.
I cant link as I’m still a new member but if you go to the main page and under products navigate to the L6 arm then under Assembly Guids/Tutorials
click on 3 Assembly Guide for L6 Arm v5. under the L6 arm section.
Step 21.
Plug the wrist rotate servo into channel 4 on the SSC-32, and the gripper servo into channel 5.
This is what i did and it blew out the gripper micro servo gears =/
Plugging the servo into the wrong channel didn’t blow out the gears; the signals are the same sort of servo control pulses, no matter which channel they come from.
It sounds more like you assembled the arm - including the wrist and gripper servos - without centering all of the servos to a 1500µs pulse first, so when you applied said pulse after assembly, it tried to go to the commanded position, ran into a physical stop (either the full-open or full-closed position), and continued to try to get there, stripping gears in the process.
If the servos are properly centered during assembly, then the worst that will happen is that your arm will respond strangely to the console commands - wrist controlling grip, elbow controlling shoulder, etc. You won’t strip out a servo by plugging it into the wrong header number, unless the signal from that header is commanding the servo to a position past a physical stop, and the servo is strong enough to chew up its gears rather than just stopping its own rotation (this is often the case in micro servos of any brand). Since 1500µs is a center position, it shouldn’t drive any axis on a properly assembled arm far enough to hit a physical stop.
I see the apparently reversed instructions in step 21. If the servos are properly centered during construction, then swapping between channel 4 and 5 shouldn’t result in any difference in servo positioning, as both channels would be getting the same position signal when the “All 1.5 button” is clicked. If some other position command is given to the arm, the results may be different depending on the amount of allowed physical rotation available for each servo component. One thing that could make a servo “griper goes nutz” is miss connecting the servo connector on the ssc-32 pins. It has beem my expeience that when a servo is powered up and does not get a proper positioning signal it can travel to a rotation limit and stall there. A quick test with a properly assembled L6 arm should show if only the reversed channels can cause the servo failure.
Hrm i followed the instructions to the last detail, including using the lynxterm software throughout the assembly . But when i decided to use the Rios software and hit the 1500 for some reason the arm spazed =/ I have rechecked all the channels several times to make sure it was all set right.
I am 99% positive that the servos were at 1500 during assembly, and if i ever moved one i tryed to put it back into the same position.
I assembled both arms in the exact same way, but when i pluged up my second one with the channels in the apparent connect order (reversed from what the instructions say) and hit all 1500 the arm lined up perfectly exactly the way it should.
I’ve been using servos for a good long while, and I’ve never had any issues with them going haywire, especially to the point where they strip out their own gears when sent a command to move to the middle of their range of motion. With a correctly assembled arm, with properly centered servos, which are plugged in with the power, signal, and ground wires the right way around, everything should work fine. Other than perhaps power issues, that pretty much exhausts my list of likely culprits.
Yeah i completely see where your coming from and what your saying make 100% sense, heck my other arm worked perfect! I just can’t for the life of me figure out what happened with the other one. I guess ill try to see if i can get some replacement gears for this one.
The instructions are wrong tho right? As you guys have said the way i have it now is the correct order.
As for the other questions dose the metal arm base need a different base servo? I simply can’t get it to not jerk but when its on the normal plastic base it works fine.
If i plug up both arms to the board can i make them do individual things? Also dose the board need to receive anymore power?
First off I apologize for the error in the assembly guides. It amazes me how an error like that could go un reported for so long. Although I doubt the error had anything to do with the spazing arm, and the broken gears, we will replace the gears for you. We will be looking over the assembly guides and make any required improvements.
The metal arm base has ball bearings in the assembly. It has very little friction and a huge amount of mass can be added. This taxes the servo much more than the injection molded version. (it has a little more friction which adds some damping. You can find the optimum speed to move the arm base servo to minimize jerky motion. You can also change it to a 645 servo which is less susceptible to this condition.
Robot Dude you guys replacing the gear would be awesome! I’m just glad that it didn’t damage anything else or burn out the micro servo. Who would i get in touch with about doing this?
As for the metal base you said i can “find optimum speed to move the arm base servo” What exactly do you mean by this? Do you mean tweaking the speed the arm uses during motion via the software or is it something else?
Although I doubt the error had anything to do with the spazing arm, and the broken gears, we will replace the gears for you. We will be looking over the assembly guides and make any required improvements.