Hi guys, I was wondering if I could have some help/advice with my Johnny 5 build. I am fairly new to robotics, this is my first proper robot build (don’t think a Boe Bot counts). I also have a neurological illness which is affecting my eyes at the minute and severely limiting how much time I can spend on the internet searching for answers, so any help and/or links is much appreciated.
I have completed Johnny 5 as per assembly instructions with a Sabertooth and SSC-32 (V2) wired up. When I come to test him in the sequencer and use the “Set all servos to 1.5ms” function I’m getting:
a) A continual whining noise from the base rotate servo
b) An occasional spasm - all the servo’s seem to vibrate slightly like he’s having a seizure
c) A couple of the servo’s are very jittering and making odd noises when moved using the sequencer.
I’ll try and upload some video’s to youtube and post the link here so you can see for yourselves.
Also can I confirm the wiring as this isn’t made clear in the instructions. Does the sequencer just need power from the 6v into it’s VS1 socket? Or should there be other connections? Obviously all the servos are in the correct pins.
On the Sabertooth Ch1 and Ch2 connectors does the Brown lead mean Ground and the Orange lead Signal?
My first things I would look at is power, what is connected to what?
That is with the Tri-track motors, I believe most of them expect 12vs (at least mine has that). So you should verify that you are giving 6vs to the servos. Most of them really don’t like 12v! Likewise sometimes you may need separate power going to the logic terminals of the SSC-32.
Check to see that it has been positioned correctly and is not trying to go to a position it cannot move to.
This can happen during upload, but can also happen when there is not sufficient current for the entire system.
Do they make that noise on their own if you remove them from the bracket?
The absolute minimum voltage for VL is 6V, and some boards simply won’t accept 6V. VL needs to be powered at 6-9V DC, and if you are new to robotics, you might consider a 9V battery. If you are comfortable with electronics, you can use a step-down voltage regulator with the 12V drive motor battery. lynxmotion.com/p-599-wiring- … ector.aspx
All servos a free to move to a further extent in each direction.
I have checked the SSC-32 power supply and there is 6.9v to it.
Using the sequencer today to turn on one servo at a time I can clarify that the servos 0, 1 and 2 (base rotate, lower torso upper torso) all make a continually buzzing/grinding noise as soon as powered on. I notice also that the buzz is loudest in 0 getting quieter as you go up through the numbers. Servo’s 3 and 4 also make a slight hum but not as loud as the previous 3.
All the other servos are silent upon powering on, however some in the right arm make a slight buzzing noise once they move and are not moving smoothly. The buzzing noise continues if left in any position other than home (0 degrees).
I’ve noticed that where the servos are attached to a C bracket with a bearing, the screw into bearing is rotating with the servo, surely it should shouldn’t rotate and the bearing should?
Should a servo be virtually silent and just make a slight whizzing noise as it moves?
Could I have damaged the servos/SSC-32 by accidentally connecting the 12v battery instead of the 6v?
Servos are normally quiet unless moving or under a load. If your servo joints are too tight for some reason placing the servos under a continous load, then buzzing maybe due to the loading. I suggest you remove the servos from the joints and see if they still buzz. Putting 12v to components that have 5v/6v maximum rating can cause damage or failure. Higher than rated voltage powering servos can cause erattic servo behavior. How are you supplying 6v to the servos?
Ok I’ve removed the base rotate servo and the one above it. When free of brackets there’s no buzz though there is still a slight grumbling noise as they move, is this usual for metal gear servos, I’m only used to plastic ones in helicopters. Could they require greasing since they have been in storage for quite a while before I built the kit?
The cause of the buzzing on the base rotate servo is when the screw which fastens the base to the servo horn is tightened, leaving it loose, ie the head protruding up a mm or so it doesn’t buzz? Tighten it, then loosen it and it continues to buzz? Any suggestions?
99% sure yes because the screws used for the servo horns are already attached to the hi-tec servos and are very different from any other screw in the kit.
The 6v goes through the supplied switch straight to the SSC-32 VS1 port, socket, thing.
I’ve put the robot back together now and the base rotate has stopped buzzing, though because the screw securing the rotating platform isn’t down tight as the robot rotates it wobbles a bit now.
Servo’s 1 and 2 (the lower torso ones) are buzzing again once the weight of the robot is back on them. This doesn’t seem to be normal looking at youtube videos of Johnny 5 but I don’t see how I can take the strain off those servos as the weight of the robot is on them? Could the servos gears need greasing having been in storage for quite a while?
As zoomkat indicated, most servos are silent if you operate them on their own. If the servo encounters resistance at the position it was instructed to move to (such as the weight of an arm under gravity), then yes, the servo will hum, and buzz if it’s really struggling. Servos make sound when moving too of course.
That’s certainly possible.
A “buzz” or sorts is to be expected - a “grumble” or the sound of teeth really grinding is not normal.
It depends how long they were not used. We have robots here which are over 2 years old and the grease has not evaporated.
The screw should not influence the motion or the sound since all it does is hold the horn to the final gear. The buzzing is likely because of the final gear pressing too much against something. If leaving the screw up a little stops the noise, then so be it.
Note that for power (12V and 6V battery, you need to remove VL=VS).
Hi CBenson, thanks for your reply. I’ve tested the servos with no brackets/load with the SSC-32 and a servo tester and they don’t buzz. Two youtube videos of the noise the servos are making:
Yes I don’t understand how the screw going into the base rotate servo horn can influence the servos movement, but it is. I’ve rebuilt Johnny 5 leaving this screw loose. Now only the two lower servos are buzzing continually (1 & 2) but because the base rotate screw is loose the base is rocking slightly under the weight of the body and this is causing a jerky movement, see video below:
In the video you can also hear the lower torso servos buzzing. I don’t understand how I can eliminate this as they are continually under strain from the weight of the body, but other peoples Johnny 5’s don’t seem to make that noise?
If I remove the VL=VS jumper then there’s no power to the board, the led is off and no servos move? To clarify I have 6v going to the VS1 of the SSC-32 and 12v to the sabertooth.
I’ve noticed my 6v battery is depleting very quickly, in 20 minutes or so. Multi meter shows it charging to 6.9 volts though. Also it’s only taking 20 minutes to charge on the universal charger, whereas the manual says it should take several hours. Could this battery have become damaged from being in storage and could it be the cause of the buzz to the servos as they aren’t getting enough power? Should I charge the battery at 0.9 amp rate or 1.8 amp rate on the universal charger? (As supplied by Lynxmotion).
It does seem to be working correctly though, and there will be some “wobble” because of the inertia of the system - you can correct this in the code. Can you remove the servo in the base rotate and record the sound on its own? The plastic case is likely amplifying the sound.
Yes, they do. All servo-based robots make noise.
VS needs to be between 4.8V and 6V, while VL needs to be between 7V and 9V (manual states 6V, but that’s pushing it). A charged 6V battery can go as high as 6.9V, which is barely enough to power VL, but as soon as you start to use the battery, the voltage will drop and you will get erratic behavior. You should either use a dedicated 9V battery for VL or a step-up voltage regulator. Johnny 5 will only last about 10-20 minutes. If the manual says the robot will last a few hours, that’s entirely incorrect and we ask that you please indicate where that is so we can change it.
Will do. I think it is amplifying it yeah. It’s more the jerky motion I’m concerned about, as the base rotate moves with the robot body on it is a very jerky movement. Is this something to correct in the code or something I need to get set up right from the start?
Sorry I meant the continual buzzing noise servos 1 & 2 are making, not the general servo whizz noise. Your J-5 here isn’t making that continual buzz. Any suggestions on what’s causing 1 & 2 to buzz continually?
Huh? Are you saying I should have the 6V going to VS1 and plug a separate 9v battery into VL and remove the VL=VS1 jumper. I have a spare 9v battery clip/harness on my desk but assumed it had fallen out of another kit as the instructions don’t mention wiring it up?
Ah ok sounds like the battery is Ok then. Sorry no the charger manual says the battery should take several hours to charge, but it charges in about 10-20 mins. Should I use 0.9amp current or 1.8amp current to charge? Or doesn’t it matter.
It should rotate well when you add a servo horn - on its own. If it’s really jerky and/or makes a lot of noise and it’s new, then we’ll certainly consider an exchange.
It’s also not leaning over (in most of the video) - the servos don’t need to provide much torque to keep the body straight up.
Either that or a voltage regulator. Otherwise you may find that your robot dies well before the battery is drained because VL can’t go too low.
Yes, you chose the right batteries to power the base and the servos.
And here’s two videos of Johnny 5 where you can hear servos 1 and 2 humming continually whatever position they are in (second video has movement so you can see even straightened up they are humming):
Position the body so it’s not bent but straight up. It should be far less noisy. If it’s still really noisy in that configuration (where there should be minimal torque required) we’ll consider an exchange. Usually a servo outright fails (stops working), so it’s odd that it works but is quite noisy.
Will do. I’ve opened it up and there’s plenty of grease in there so it’s not that. Will put it back together and see how it is now. I’ve got some servos ordered for another project so I’ll try using one of them and and compare.
Be careful if the servos are from a different supplier - the brackets are designed with specific servo dimensions in mind, and if a servos is even slightly off, it may not fit the bracket.
