I had bought a fancy power supply thinking "This is The One" that will power the whole robot, but I guess I was wrong. You see since the beginning of this project I had been using a very small power supply DC6V3A I had laying around in my workshop. But by adding more and more servos to it, I came to realize it was not enough anymore to power up the 22 servos of InMoov. During the initialization, each servo seems to draw about 2 Amps. I guess I was just lucky with my small supply to already be able to run the arm and not fry it instantly.
This thing was expensive, but it was sold by the same kind of shop that sales servos for hobbiest so I thought it must be compliant. I'm no electrician, I do all those things by guessing...
Okay, I received the Power supply, I was excited because I was going to finally get the whole robot to move. First thing I did was to test with a simple Arduino sketch with only one servo. It worked perfect!
Since I had the right arm connected to the Arduino Uno, I plugged it and ran the simple Arduino sketch again. Perfect!!
At that point I had to think of making a small pcb board to connect all my servos and my two Arduino board all to that single power supply.
Once again I ran a simple test with my two Aduino boards and only 8 servos attached. It went perfect again!
Boy, was I getting excited!
So I went straight forward and plugged every thing together, 22 servos, 2 Aduinos, 1 power supply. I had used only one side of the output of the power supply, instead of both, which can each deliver 20Amps and I think here lays my mistake.
I ran the simple sketch which is only moving all the servos from, let say, 0 to 30 position. Some of the servos were already at 0 position. Then they all had to move to their new positions, here started some strange behaviours. Some of the servos were jittering (shaking), and the movements of the robot became erratic.
I unplugged everything, rechecked all my connections, everything seemed okay.
At that point I thought, I must have plugged or touched something that did that strange acting, and decided to go on.
So excited I was , it was the time to get InMoov controlled through Myrobotlab.
Here starts the initialization, and I get this same kind of strange behaviour, all servos buzzing, erratical moves.
Then all of a sudden one of the arm starts to twist way further then what it is supposed to do!!
WOW! I unplugged everything...
I ran the same test again, but this time everything went off at once, no more power. The power supply is protected against short circuit, thermal heat, and overload drawing.
I checked all the connections one by one again, nothing was wrong.
What was the problem, so I restarted with my first initial test, 1 Arduino, 1 servo, simple sketch, it was not perfect at all anymore. It was acting totally erraticaly...!
And since then of on.
There must be something damaged in the power supply, strangely if I use it with another device, like a little DC motor, it works normal.
So, end of the story, back in search on the net. I read on this page what I hadn't found before about switching power supplies with servos.
Now, I have ordered three batteries with a small charger. They were very cheap when I passed my order, 8 euros per battery. I think that will do for now, I also had found some Lipo batteries but they are rather expensive.
I really would rather a power supply, because I just don't want to have doubts about the power or wait for charging time. I need a DC 6V 44Amps or more, no swithching, with a 250V input.
Would be great if someone has an idea. Any suggestion is welcomed, please post in the comments.
In the meanwhile I have been designing and printing more parts for the head. I also redesigned the top of the front torso, the other was going too high in the middle, and it bothered me because it wasn't taking a human shape structure.
The jaw has it's own servo motor mounted and can be actionned. I still need to test the microphones in the ear circus amplifiers, but this is pure creating guessing. I have no idea if it's going to help InMoov to hear better the voice commands. But hey, why not try something different since I can print and design what ever I want!
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| Robot head sideway without ear |
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| InMoov has ears and jaw attached |
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| Changements have been done on the torso structures of InMoov |
