I am a beginner and this is my first robot. I was thinking of building it with an Arduino Leonardo, Adafruit Motor Shield, ultrasonic sensor and three 9g servos. I decided to use servos since motors are heavier, costs more and are hard to mount. I wanted to keep the robot small, compact and lightweight. I am planning to put the third servo on the header pins. So here r my questions:
What type of battery should i use (voltage and amps)?
Should i power it up thru the terminal block or the barrel jack?
9g servos are probably a little underpowered for driving a non-tiny bot, but several places sell "standard" servos [~44 oz-in] already modified for continuous rotation, although it's not too hard to do yourself.
For a first robot, it's easiest to start with servo drive, and use the 44 oz-in servos. You can always go to motor-drive and h-bridges for your 2nd robot.
The 44 oz-in servos will provide more torque than the 9g servos, so you can build a larger bot that can mount a regular UNO board and a range of sensors, like sonars, Sharp IR rangers, etc. Once you start adding things, the weight starts to build up, and you can overload the smaller servos.
The best sensor system is to use a panning servo with sonars and/or Sharp ranger on top. The 9g servo should work fine for this.
Also, for a reasonable price, you can buy a complete kit that includes all of these elements. This uses motor-drive, but includes the h-bridge. This is what I would do myself. Similar available from many other places.
This includes the battery holder, plus you'll notice the controller board has 3-pin headers mounted on it, so it's easy to plug in servos and sensors. You see a lot of people interfacing Rduino boards the following way, but this is a really crappy way to do things.
I am using three servos (each 4.8v), sonar( 5v) arduino board and an adafruit motor shield (1.2v) -www.adafruit.com/products/1438. Shud i use lipo or li ion? And what voltage shud it provide? The battery shud be lightweight. I was planning to use cell phone batteries (soldered together). 9v seems to be low.
well it seems i had made up my mind. im gonna use 2 TowerPro MG92R servos and a 9g servo for panning.
7.4v 1500 mAh battery. I think the micro metal type servos provide more torque than nylon gear.
Anyway.... thanks guys!