Killer Robots 101 with Gobot

Killer Robots 101
Golang edition

about(self):
Thejana Satanarachchi (TJ)

EstimateOne Pty Ltd.

github.com/thejanasatan

https://estimateone.com/our-team

Architecture
Ubuntu 14.04 (trusty64)
ROS node graph ROS services ROS topicsBaxter Drivers
ros_masterrospybaxter_interface IK Solverparam_server
baxtervr_ws_proxy
baxtervr_action_server
UNITY VR

SENSOR CONTROLLER ACTUATOR
Software Output DevicesInput Devices

Things I wish I knew
• Inverse Kinematics

• Physics thing

• Calculates the angles for joints on a limb based on the tip

• Could also be the force needed to move each joint to the
appropriate position so that the tip of the limb arrives at a given
coordinate as a result

• Quaternion

• Another physics thing

• Used to calculate the rotation of a limb/joint of a robot

• The coordinates of a joint would be in the form 
[ (x, y, z) (x, y, z, w) ]

Robot OS (not really)
• ROS is a meta-operating system

• Supports Ubuntu on amd64 and ARM + more debian distributions

• Started in 2007 at Stanford - a place called Willow Garage primarily for
PR2

• Licensed under permissive BSD

• Supported by OSR foundation

• Mostly a message passing infrastructure

• Helpful libraries for robot-y things (IK, path planning etc)

• Used in a lot of real world robots

• RMIT University has a ﬂeet of drones running on ROS

ROS Core
• Is an anonymous PubSub infrastructure - asynchronous

• Uses ROS topics

• Based on custom message formats over TCP - can use UDP too

• RPC based ROS Services

• Lock-step behaviour when passing messages

• Based on XMLRPC

• Node Graph

• Addressed like a unix ﬁlesystem

• Has local and global namespaces

• Node registry - resides in master

ROS Core cont.
• Distributed Parameter Server

• Resides in the master node

• Key-value database

• Types

• Message Types (msg)

• Service Types (srv)

• Packages - with manifests (build + dependencies) - package.xml

• Manifests and Conﬁgs

• Based on XML

• URDF - used to deﬁne a robot

Gobot
• www.gobot.io

• github.com/hybridgroup/gobot

• Is an layer of semi-idiomatic abstraction for robotics and IoT for Go

• Already supports a lot of platforms and popular interface drivers both
standard and proprietary

• Extensible:

• Platforms

• Drivers

• Supports combination of platforms

• Has a lot of examples to learn from on https://gobot.io/documentation/
examples

Gobot Platforms
What the heck is a platform?

go get -d -u gobot.io/x/gobot/platforms/raspi

Gobot Core
• Robots

• Primary abstraction in Gobot

• Can represent a rover, drone or any other machine

• Takes in slices of Adaptors/Drivers to compose a robot

• Adaptors

• Packages to control platforms

• Usually speciﬁc to a platform targeted

• Drivers

• Packages that control hardware interfaces

• Supports popular interfaces such as I2C, SPI, GPIO, PWM

• Uses a custom implementation of the sysfs package

go get -d -u gobot.io/x/gobot/drivers/gpio

Gobot Flavours
• Classic Gobot

• Simplest way to use gobot

• gobot.NewRobot()

• Metal Gobot

• Like Sphero

• Not using gobot abstractions directly

• Master Gobot

• Master-slave pattern

• Enables control over swarms of robots

• Go has experimental support for - in exp/io:

• spi

• i2c

• There are more up and coming packages for interfacing with h/w

• ROS client libraries for Go

• https://github.com/akio/rosgo

• Working on a ROS2 client library

• Calling it rosco

• Based on rcl - oﬃcial C library

• github.com/thejanasatan/rosco

• Contributions welcome! 
• ROS/Gobot Workshops for students at RMIT

• Do some robotics work in Rust too - shoutout to any rustaceans

Killer Robots 101 with Gobot

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