Killer Robots 101 with Go

A talk about ROS (Robot Operating System) and Gobot at Golang Melbourne July 2018

Transcript

1. Killer Robots 101 Golang edition
2. about(self): Thejana Satanarachchi (TJ) EstimateOne Pty Ltd. github.com/thejanasatan https://estimateone.com/our-team
3. Video!
4. Architecture Ubuntu 14.04 (trusty64) ROS node graph ROS services ROS topics Baxter Drivers ros_master rospy baxter_interface IK Solver param_server baxtervr_ws_proxy baxtervr_action_server UNITY VR
5. SENSOR CONTROLLER ACTUATOR Software Output Devices Input Devices
6. 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) ]
7. ROS: A Gentle Intro TL;DR;
8. 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
9. 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
10. 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
11. Let’s talk Gobot
12. 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
13. Gobot Platforms What the heck is a platform?
15. go get -d -u gobot.io/x/gobot/platforms/raspi
16. 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
17. go get -d -u gobot.io/x/gobot/drivers/gpio
18. Let’s look at code… YAY!
19. 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
20. Is this enough?
21. • 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
22. • 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