🦎 Gecko

My robot software.

• Supported OS'es: macOS, Linux Ubuntu, Linux Raspbian
• Doesn't use ROS, ROS and ROS2 is a pain to install and maintain on macOS and various linux systems
  • Uses some of the same ideas, constructs, architecture ideas, APIs but not strictly adhering to them
  • ROS tries to be too much
    • catkin/colcon are crap ... simple cmake is better
    • do not need to monkey with env and constantly source some setup file
• Uses Zero MQ as the inter-process communication (uses both TCP and UDS) instead of RPC-XML or DDS
  • looked at Google's protobuf, but was more complex than I needed
  • using msgpack to serialize data currently, but could be changed to something different
  • instead of ros2 use gecko.py core as the message hub
    • produces performance data (see below)
• json - config and launch files
• All of this runs on Raspberry Pi 3 with Raspbian
  • Also runs on macOS (UNIX)

Architecture

• Programming languages
  • C++17
  • Python 3.7
  • bash scripts for building, but might move to zsh because of macOS
• GeckoCore is a hub that tracks what computer publishes what topic and prints node cpu/memory usage
  • Actually, when gecko processes start up, they tell geckocore their pid numbers so it can track usage using psutil library
  • Obviously this only works on processes located on the same machine as geckocore
  • GeckoCore really just displays info and keeps track of publisher topics/addresses
  • If a Pub/Sub is on a remote machine, then it's performance data is not displayed
  • There currently is no mechanism to get the remote performance data
• Inter process communications (IPC)
  • Publish/subscribe
  • Request/reply
  • Communications can be TCP or Unix Domain Sockets (UDS)
  • GeckoCore is optional, if you know the TCP/UDS address, you can tell the pub/sub or req/rep where the endpoint is. GeckoCore is just there to make things easier and provide performance info
• Tools
  • gecko bag: save data for replay later
  • gecko topic: display pub/sub
  • gecko service: display req/rep
  • gecko launch: run multiple nodes at once

Serialization

• gecko-msgpack
• gecko-protobuf

Organization

C++

Libraries are stored in /opt/gecko.

Python

Use pip to manage libraries and run-time software

Nodejs

This is a future effort ... I want to have a webserver running that can provide visual feedback on robot

Transport IPC

Endpoint protocols:

• Transmisison Control Protocol (TCP): tcp://host:port
• Unix Domain Sockets (UDS): ipc://path/to/file

Publisher and Subscriber

1. Start a GeckoCore instance
   1. The key defaults to host name, but can be set to any string
   2. The idea is every robot (computer) can have a core running
2. Binder: only 1 per port, can be either pub or sub
   1. Binders can use either TCP or UDS
   2. Binder opens a random port for data for TCP
   3. Note: either a publisher or a subscriber can bind to an endpoint
   4. A multicast message is sent to core
3. GeckoCore acknowledges the binder with an ok message
4. Connecter: can be many per endpoint, can be pub or sub
   1. First connector sends a multicast message to core asking for the endpoint for a topic
   2. Only 1 service can publish a topic and it exists on only 1 endpoint
5. GeckoCore:
   1. If topic is found, return the endpoint and an ok message
   2. If topic is not found, returns None

Request and Reply

In work

• python working
• c++ needs to be finished

Multicast Messages

Multicast is used to talk with geckocore and pass information between. The advantage is you do not have to know the IP/Port address of a given core. You use a key (ex: dalek, local, bob, whatever) that only that core will respond too. You can thus make it robot centric, or whatever you want centric.

Connect: multiple nodes can connect to endpt
node -> core: key|topic|pid
core -> node: key|topic|endpt|ok

Bind: only one node can bind to an endpt
node -> core: key|topic|pid|endpt
core -> node: key|topic|endpt|ok

Components

Gecko is written in a couple languages and uses common cross-language cross-platform libraries to bring everything together. The primary 2 languages are C++ and python 3.

Component	C++	Python	Nodejs
tools		X
IPC	X	X
serialization	X	X
visualization

Sensors and Hardware

Gecko libraries (publishers and/or subscribers) are made for the following:

Sensor	Python	C++
ydlidar		X
nxp imu	X
rplidar		X
tfmini		X
PiCamera	X

Hardware	Python	C++
Raspberry Pi	X

Tools

Like ros2, gecko is a bunch of tools written in python:

• gecko core run|ping
• gecko multicast a|b|c
  • send multicast messages (just simple a, b, or c) between computers to test connectivity
• gecko bag play|record filename --loop
  • bag will use the python library the-collector and store data using pickle so any python jupyter notebook or tools can use the data without gecko
• gecko topic echo|bw|pub topic message
• gecko log ??

ToDo

• Windozes support ... ha, ha, ha, ha ... probably not :P
• Create a debian package for linux
• Look at cross-compiling with docker for arm and building debian packages for simpler install

Robot stuff

• visual odom https://github.com/MichaelGrupp/evo https://michaelgrupp.github.io/evo/
• AI vision using http://cocodataset.org/#home
• AI https://skymind.ai/wiki/convolutional-network
• https://projects.asl.ethz.ch/datasets/doku.php?id=kmavvisualinertialdatasets
• Look into NN with https://keras.io/
• Does https://openai.com/ help with anything?

MIT License

Copyright (c) 2010 Kevin J. Walchko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.