Hexapod proyect

Hi, I am new to this forum but i wanted to ask something. I have a project about making a hexapod with arduino UNO using 12 microservomotors of 9g and a bluethoth hc-05 module. What happens is that I feed three servomotors from the same arduino board and I realized that the arduino does not provide enough current for the servos so I was thinking of connecting them with an external battery, investigating i realised that the lipo batteries are ideal for this case for the fact that have enough current. My question is that if I buy a lipo battery of 7.4v and connect it to the Arduino and from the same battery I sack another cable connected to a protoboard that feed the 12 servos(mi hexapod does not use 18 seromotors as usual) is there any way that this voltage can decrease it so that the servos do not burn? (cause the servos are recommended to use 5v average)Or is there another type of battery of 5 v that can connect so much to the arduino so that it sends the orders by pins pwm and the servomotors? Psdt: about how many ma should be the lipo battery? iam not sure if 2800mA is enough for the 12 servos and the bluethoth module

I think the 2800 will be plenty. But I'm worried about your servos. Those little 9 g are not going to lift much weight. I used a switching voltage regulator to cut the lipo voltage down to 5 V. I used 11.1 2100mAh packs because I have many of them.

They lift up to 1.6kg(theorically) , and i have already program one leg and they work perfectly.
how did you connect the lipo with the arduino and the servos at the same time? sry if it sounds like a noob question iam just starting with arduino.Did you connected directy the lipo to the arduino and from it you send the current to the servos? or did you connected the lipo to a protoboard and one pin goes to the arduino vin and another to the switching voltage regulator to cut the pole voltage ?

Do your weight calculations take into account the length of the leg?
Ours did not. :smiley:
we ended up buying stronger servos for the 6 weight bearing servos.

Here is a link to an old thread where I posted pics of what I was doing.

Inverse kinematics is fun!

As I recall, we wrote an approximation for arctan because the full function is too slow.

Oh, here is a movie clip of its first steps.
We did a lot to smooth out the gate. We were just getting in to alternate gates when we moved on to other projects.