First Project Parts List

Let's Make Robots Projects Showcase
1

Hey all,

I’ve been looking at the site for some time now, finally decided what I’m going to build :slight_smile:

I’d love it if someone could look over my parts list and tell me what I’m missing or what I’ve done wrong. I’m sure at least half of it is wrong, knowing my luck…

1 x Extreme Hexapod 3-R Robot Kit (no electronics)
1 x Add On Deck
1 x HSR-1422CR (57 oz.in.) Continuous Rotation Standard Servo
3 x HS-422 (57 oz. in.) Standard Servo
2 x Aluminum Tubing - 6.0"
2 x Aluminum Tubing Connector Hub (pair)
2 x Aluminum Multi-Purpose Servo Bracket Two Pack (Brushed)
1 x Aluminum Long “C” Servo Bracket with Ball Bearings Two Pack
1 x Aluminum “C” Servo Bracket with Ball Bearings Two Pack
1 x Aluminum “L” Connector Bracket Two Pack
1 x Sharp GP2D12 IR Sensor
1 x Ultrasonic Range Sensor
1 x SSC-32 Servo Controller

The plan is to take the Hexapod, put the add on deck on it, mount the continous rotation servo on the deck, and place an arm on top of that. The arm should be 3DOF so that the Ultrasonic range finder can be mounted on the end and used to scan the entire area around the bot, including right in front of its feet (hence the arm instead of a pan/tilt setup).

The IR sensor will be mounted on the arm as well, pointed towards the ground in front of where the bot is going, to make sure the ground doesn’t dissapear without the bot knowing about it.

I plan to use an MSP430x449 microcontroller (I have several already) to control the bot, with lookup tables for where the servers should be positioned and the resulting readings if certain objects are present (ie, if the arm is held at position one, the IR range finder should get a reading between 10 and 12cm). As well, I’d like to have the ultrasonic rangefinder output to Zaurus mounted on the bot, so that an accurate map can be created of objects around it, and hopefully some detection of humans, dogs, cats, etc can be done.

Sound like I’ve missed anything?

Thanks!
Grecko

2

Are you aware that the continuous rotation modification of a servo destroys its ability to hold a position? If you want to have any control over its location you’ll need some other means of measuring it like a quadrature encoder.

3

The servo is made continuous by removing the stop-plates on the reduction gears.
Without these plates, all the servo will be is a motor with a speed controller and reduction gearset.
Continuous rotation servos are usually used to drive small rovers.

Alternatively, if you take a regular servo and use it to drive a gear that’s half as large, that gear will turn 360 degrees, which is what you seem to be looking for.
With that setup, though, you’ll get a servo that’s twice as fast and half as strong.

You forgot the most important part of your bot.
Batteries.

In my experience, robots tend to go on strike when you don’t give them food.
:wink:

I’d suggest getting two 6V battery packs, two male quick connectors, and one charger.

This way, you can charge one battery while you use the other.

Ask Jim if he thinks the stock servos for that kit will support all of the added weight that you’re going to be carrying.