ubiquity_launches Launch File Repository

Development Overview

All of the Ubiquity robots use ROS (Robot Operating System). ROS breaks a robot application into a multitude of ROS nodes (i.e. processes) running on one or more processors that communicate with one another via internet protocols.

The usual method for teaching people to develop ROS robot applications is to point them at some ROS tutorials and say “go at it”. Unfortunately, this is a little bit dumping buckets of blood into shark infested waters and going for a little swim. At Ubiquity Robotics, we want robot application developers to have a much less traumatic experience. For this reason, we have invested a great deal of effort to make ROS robot application development as easy as possible.

The reality is that setting up a workable software development environment for developing ROS applications is actually pretty involved. One major complication is that the robot typically does not have a display, keyboard, and mouse. Even if it did, it not particularly easy to walk around with the robot as it moves. The more workable solution is to develop software on a stationary platform like a laptop or a desktop, and communicate with the robot via a wireless internet connection. A further complication, is Ubiquity Robotics is using a Raspberry Pi 2 processor with the ARM7 instruction set, whereas most laptops and desktops use the x86 instruction set. We have to make sure that each machine gets the right instruction set.

The Ubiquity Robotics application development environment assumes that there are two processors. The robot processor is attached to the robot and the development processor is associated with either laptop or desktop computer.

Ubiquity Robotics currently uses a Raspberry Pi Foundation Raspberry Pi 2 Model B for the robot processor. Since “Raspberry Pi 2 Model B” is a mouthful of words, we shorten it down to a more manageable “RasPi2”. The RasPi2 is a quad-core ARM Cortex-A7 CPU with 1GB of RAM, with 4 USB Ports, an Ethernet port, a camera interface, and a micro-SD card. We plug a dual-band USB WiFi Dongle into one of the USB port slots to provide wireless connectivity with the development processor through a commercial off-the-shelf WiFi router.

The development processor must be a 64-bit x86 hardware architecture processor. You can either run some flavor of Ubuntu natively on the processor, or you can run a different operating system (e.g. Windows, MacOS, Solaris, etc.) and run VirtualBox to run the Ubuntu operating system. Neither 32-bit processors nor other virtual machines (e.g. VMWare, Parallels, etc.) are supported.

ROS currently only runs under Ubuntu and its variants (e.g. Kubuntu, Xubuntu, Lubuntu, etc.) No other operating system options are currently supported by the ROS community. To be consistent, the VirtualBox image that we recommend that you use has Lubuntu installed on it. We also install Lubuntu on the robot processor, just in case you choose to plug a monitor/keyboard/mouse into the RasPi2. Lubuntu is a very light weight window system that does not over tax the RasPi2 robot processor.

We really encourage people not to cut corners when it comes to setting up your WiFi network. If you have heard the saying that “a chain is only as strong as its weakest link”, our experience is that WiFi is the weak link in robotics. We strongly recommend that people use dual band 802.11ac USB WiFi dongles to provide wireless technology. Similarly, we recommend that you invest in a superior dual-band WiFi router. You can spend an enormous amount of time tracking down and eradicating flaky WiFi issues and it is better to simply avoid the issues by using better hardware and better antennas.

We use a technology called zeroconf to provide human readable names for the various processors on the computer network. Each robot processor and development processor must have a unique host name and MUST run zeroconf. The DNS will present the DNS names as hostname.local where, hostname is the host name of the robot or development processor.

The ROS community extensively uses Secure Shell to communicate between computers. The secure shell protocols provide a secure and encrypted link between computers. We require that password keys be properly set up between the development processor and the robot processor such that a secure link can be established without prompting the user for

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