For my current project I need to control 13 digital servos.I am using an Arduino UNO R3 clone (Sainsmart) and an Adafruit 16 channel servo driver board (not the shield).
When I turn my robot on all 13 servos want to go in the start position but the problem is that I can't provide enough current for the servos so they are just wiggling around.I tried to use 4 1.2 V 10.000mah batteries in a row but that wasn't enough when the 13 servos are moving at the same time.
So now I am searching for a cheap rechargeable battery to run my 13 servos.
Thanks for reading, I hope you can help me !
(If there any misstakes in this text please tell me I'm german but I want to learn english)
I guess you are using microservos, if so they draw about 200mA each; you will need a battery which can provide 13*0.2 A. That’s about 2.6A . Look for projects here like hexapods, usually it’s used a current regulator and LiPo batteries.
Don’t worry about mistakes, it’s part of the learning:)
I’ve never liked setting all I’ve never liked setting all my servos at the same time at startup if I use a lot of servos. I’d rather set them in a loop with a delay after each.
You don’t care about the You don’t care about the capacity of the battery (mAh), but the maximum current the battery can provide (which is capacity × C rating). Also, connecting the batteries in a row will give you higher voltage, but not more current – for more current you connect them in parallel.
Finally, you can modify your code to not initialize all the servos at once, but instead add a small delay between initializing each. In addition to lowering the power requirements, this will also look quite cool, especially when you do it with hip servos first, then knees, and then ankles.
Since you want to learn, I think it will be helpful to point out your mistakes:
projekt → project
I'am → I am
enought → enough
currency → current
in row → in a row
mveing → moving
the same time → at the same time
First sorry for these embarrassing misstakes (projekt or enought what a shame! But thanks in germany you say: You learn from misstakes).
I didn’t connect the batteries in a row to get approx. 5 V, but to get higher capacity.Anyway I don’t know what you mean with “capacity × C rating” what is C rating ?Is it the currency rating ? And what does that mean?
It depends on how it walks. It depends on how it walks. Even having a few less servos running may help the batteries. This is one of the reasons LiPos are used: because they can source a LOT of current.
But having control over the boot up process helps the situation where servos can move against each other (depending one where your limbs are).
Also I think it looks neat: Think of a rag doll coming alive joint by joint.
It should become an AT-AT and when it walks nearly every joint is moveing or just holding the position.But I am not very confident that it will be able to walk one day because the balance point is so high (40 cm !).
I have the same servos and a similar amount and I have two buck converters 15A peak to deal with the current draw. MG996 servos use lots of current and heat up quickly so there is really no need to buy expensive high capacity batteries, the servos will overheat faster than you can drain a high capacity battery. (I’ll be using 3s (approximately) 3000mAh Lipos, which I still have to buy.)
Can’t find the datasheet of the MG996R anymore, but according to the datasheet the operating current is about 1A and the stall current about 2A.
Most small bipeds move by Most small bipeds move by static walking, which is why most have big feet.
You have tried something very difficult: the only way to make it walk like it did in the movies is by dynamic walking. We move by dynamic walking.
The main difference is that in static walking the object is stable at all points in its gait. With dynamic walking there will be times where the object is not stable. However dynamic walking looks much more natural to us.
Might be, but I doubt it will work I think the balance point is to high 40 cm are are a lot the legs are 40cm long, from the bottom to the nee joint 20 cm and from the nee joint to the body 20 cm too and another 20cm to the top but the main weight is in 40 cm heigh.I now have got some problems with just standing I don’t want to imagine what problems I get with walking.But if it won’t work, I’ll try to build something different.
May be this is not the best solution, but I am using Sanyo NCR18650BF 3.7V 3400mAH organized in battary pack. This is most advanced /cheepest solution I was abel to find. Since it is 3.7V you will need stack them in series by 2 and use voltage regulator in your power line, like this, for example: https://www.sparkfun.com/products/107. Some devices can accept 2 x 3.7 = 7.4 V directly because already have such regulator on board.
