Wanting to build a Hexapod robot

Hi everyone! I'm hoping that the forum might be able to provide me with some guidance. I'd like to build a hexapod walker robot, and am in the initial planning stages. I have a background in CS, and am starting to get into electronics, and robotics, as a hobby.

I have an Arduino Uno that I'd like to use as my micro controller, and would like to support a stupid number of servos, and sensors.

I'm thinking that I'll want to use a "large" RC battery to power everything. I'd like to get away from using AAs! To those ends, I'm thinking that a 12v RC battery will suit my purposes, and I'll use one of these to regulate the voltage to something consistent. I'm thinking I'll want a steady 12v off my battery, and then run that through some linear voltage regulators in parallel to give myself a 12v, 9v, 5v, and 3.3v line. One thing that worries me is the fact that those regulators are advertised as being non-isolating. Is that something I should worry about?

As far as the servo control is concerned, I'm thinking that a few of these I2C servo boards will work nicely. I'm thinking that those will allow me to run my servo's off of 12v (or however much they need), while running my Arduino off of 5v. Those little boards should allow me to control quite a number of servos. Each of those boards should allow me to control 16 servos, and three of them should meet all my needs.

I'd also like to have a variety of sensors on my robot. Since there are a limited number of input available on the Arduino, and I'm already planning on using the I2C bus, I'm thinking that a few of these will allow me to get analog signal values into the Arduino via the I2C bus pins. Since the servo controller, and the DAC both use the I2C bus will I be able to have them both on the same line? Each of the DAC boards can only support two analog inputs, and since I can only daisy chain four of them together it might be best to have multiple I2C buses running at the same time. Basically, having one I2C bus on one pair of pins, and another on a different pair of pins. Can I do this on an Arduino? Are there better DACs for the Arduino available?

I would eventually like to create my own circuit boards, such as this. I'm thinking that mastering the I2C bus methodology is something I'll want to do. The article I just linked to does a fair job of explaining how I can use an IC to expand the I2C bus outputs. Is there a similar tutorial available for creating an expandable I2C DAC set up?

Most hobby servos use 4 to 6 volts for power. I'd recommend a switch-mode 5V regulator to provide 5V from your battery to run the servos and Arduino. Figure about 1 Amp per servo.

You can control 12 servos directly with an Arduino UNO and 48 with an Arduino MEGA.

You can get really cheap servos from AliExpress.com. You can get "SG90" 9 gram Micro-Servos for $1.50 each. For heavier duty you can get the MG996R with metal gears for about $5 each.

I suggest you look at existing hexapod designs so you don't try to reinvent the wheel. Lynxmotion has a number of kits with assembly instructions you can study to see what parts are known to work. They also make the ssc-32 servo controller board which you might consider. At one time they had an arduino based servo controller that might be of interest.

johnwasser: Most hobby servos use 4 to 6 volts for power. I'd recommend a switch-mode 5V regulator to provide 5V from your battery to run the servos and Arduino. Figure about 1 Amp per servo.

You can control 12 servos directly with an Arduino UNO and 48 with an Arduino MEGA.

You can get really cheap servos from AliExpress.com. You can get "SG90" 9 gram Micro-Servos for $1.50 each. For heavier duty you can get the MG996R with metal gears for about $5 each.

That's really great! I was just doing some shopping for servos. I'm a little concerned about the weight considerations. I'm planning on making things as light as possible, and am considering using PVC foam board for my first foray into they types of projects. This article seemed to suggest I can make a decent chassis out of the material. I'm hoping to check some out at a hardware store. I think I have the rough concept for the power supply, and motor control down. The sensor input seems like it'll be the next big thing to worry about.

zoomkat: I suggest you look at existing hexapod designs so you don't try to reinvent the wheel. Lynxmotion has a number of kits with assembly instructions you can study to see what parts are known to work. They also make the ssc-32 servo controller board which you might consider. At one time they had an arduino based servo controller that might be of interest.

I'm wanting to get away from kits as fast as I can. I've been playing around with the Make:it Robotics Starter Kit, and it's time to move on.

Search thingiverse.com for hexapod designs. Even if you don't have access to a 3d printer, the designs will at least point you in the right direction. If you do have access, then a lot of the kits on there are already designed for use with arduinos, and will greatly simplify your project.