KiwiDrive HouseBot

From Forskningsavdelningen Wiki
Jump to: navigation, search

Contents

Log

[2011-07-05] New section, quick update: this project is NOT dead. The robot IS working. It CAN be controlled over the Internet. The user queueing system IS in place. All IS well. BUT - we don't have an internet connection because the the fibre installation was delayed... significantly. Once that is up, motivation WILL return. We are also waiting for awesome 8Ah batteries after which we will build a docking (or rather loading/unloading/charger) station. THEN my good friends, you will be driving this 'lil guy around (for 5 minutes at a time). Also, my camera got stolen - hence the lack of pictures.

Participants

Forks

Introduction

As we move to a new location, what better way to celebrate/mourn than to take on a new project?

We're building a housebot!

Once the project began design stage we realized that focusing on making it easy for others to reproduce was a good idea. Therefore we choose to use nothing but standard components. Nema 23 stepper motors and drivers are standard, cheap and common due to the increase in DIY CNC and Reprap manufacturing. The Arduino Uno is available across the world. We also only use metric standard components (sorry about that US) such as M5 threaded rods and M4, M3 screws for the smaller components.

Omnidirection wheels however are not exactly standard components, but given the simplicity of the drive mechanism it would be very easy to adapt the design for other wheels and shafts of a similar size. We have also made sure it is easy to re-design the drawings to account for other types of motors and bearings and we've left significant space (length-wise) for larger motors and gearboxes.

Although we did run into a few bumps during the first build (all of which have been solved) I believe we have managed to prove that this project can very well be completed over a dedicated weekend, given that parts have been pre-purchased.

As soon as the first trial build KiwiRay1 is completed, all plans and code will go open source, so check back here until then!

Let's go online!

Teaser?

One of the main objectives from the start is wa make the robot publically available on the internet. This means that anyone will eventually be able to log onto the robot and control it by remote. This required some specialized software and after surfing the interwaves for a good while we realized that to be able to do what we want, with the latency we need, we would have to go for technologies simalar to those used in gaming as opposed to traditional streaming technologies. In fact, some of the methods we use are similar to the dark magic that recently begun to allow players to play high-resolution games being run on a remote server instead of the local machine - although we do it on a much, much smaller scale.

After reading the "Diary Of An x264 Developer" article on "The best low-latency video streaming platform in the world" we started implementing a streaming/control server using the x264 library and settings discussed in this article. To enable very low latency streaming, several x264 technologies needed to be implemented:

RoboCortex Client screenshot. Wired power supply, reflection showing KiwiRay "headlights"

These technologies, in combination with lossy UDP datagram communications, allows us to fetch an image, encode it, receive it on the other end and finally decode it without any latency other than the CPU time required for the process and the network latency, both of which we can't really do anything about. In practice we get below 100mS on a good connection, most of which is internal latency in the webcam we are using (read: better webcam, lower latency).

On the receiving end we use FFMPEG H.264 decoding to produce the final image, which is rendered by SDL.

The streaming solution was dubbed RoboCortex and is today completely abstracted from KiwiRay and our choice of communications. KiwiRay and IPv4 UDP is implemented under RoboCortex using plugins.

This means that RoboCortex can now be easily adapted for any kind of video feedback remote control applications such as omnidirectional robots, cars, helicopters, etc. provided they are capable of encoding and transferring video at the desired bitrate and resolution. A variety of multi-user multi-protocol implementations, as well as single-user direct connections can be easily developed using the new plugin interface.

RoboCortex is open-source and cross-platform for Windows and Linux.

Source code

Project status

Project is currently in deployment stage (we are waiting for a stable internet connection)

Coverage (videos, pictures, articles)

Design

Current Designs

This is the kiwiray platform - a NEMA23 kiwidrive designed by Forskningsavdelningen to be printed in any 4mm material using laser, water, plasma, cnc-routing or lots of patience and manual labor. It will be the base for our KiwiRay1 house-bot and it has mounts for a charging dock+webcam(+gripper?) module as well as a top platform that (in our case) will house the brains - a micro itx pc. It is powered by three NEMA23 motors and the electronics consist of three general purpose stepper drivers, and an Arduino Uno to coordinate motion and provide an I²C-based expansion bus.


Alpha Five
To get an idea what it will look like fully loaded.
Used for KiwiRay Beta One - our first build.


Alpha Seven
Uses laser-cut snap-lock parts to replace many components.
Axles moved down for better ground clearance.
Note: tried it (plexi&wood) - no good. Requires mechanically tolerant materials.

Parts (Alpha Five)

Kiwidrive platform parts
Front module parts
Shared parts
Computer platform

Previous Designs

Alpha One
First iteration

Alpha Two
Improvements to rigidity

Alpha Three
Improvements to assembly
Measurements (still valid)

Alpha Four
Webcam module, axles+adapters

BOM

4m M5 threaded rod SEK  79,60
100x M5 nut SEK  39,90
100x M5 washer SEK  24,90
4x Omni-directional wheel USD  49,98
12" 1/8" Square axle USD   8,96
8x Ball bearings SEK  71,68
10x Axle stoppers SEK  74,00
3x Stepper motor drivers EUR  54,93
3x Stepper motors SEK 787,50
1x Servo USD   4,73
1x Arduino Uno SEK 259,00
Retrieved from "http://wiki.forskningsavd.se/index.php/KiwiDrive_HouseBot"
Personal tools
Namespaces
Variants
Actions
Navigation
Toolbox