Playing With Google Glass

Google Glass

The main scope for my thesis is to control a gimbal via Wi-Fi.Google Glass is a wearable technology with an optical head-mounted display developed by Google X, a semi-secret facility run by Google which makes major technological advancements. Since its release, Google Glass has been discontinued following accumulation of user feedback, both good and bad. Google decided to close the program in order to focus on future versions of Glass and to improve on the current platform. This has positive implications for this project since the technology being used is only available to a limited audience and is still considered to be cutting-edge technology. Unfortunately this also means that the amount of helpful resources available are minimal and there are only a handful of scholarly articles focussed on Glass, none of which involve gimbal control.

Glass displays information and exhibits hands-free control properties. It contains a multitude of hardware and software sensors. The operating system is based on Android 4.4.2 (API 19) and uses the Android Studio IDE to develop functional applications with real-world interactive elements. Some of the useful hardware sensors on Glass are:

  • Microphone
  • 3-axis accelerometer
  • 3-axis gyroscope
  • 3-axis magnetometer (compass)
  • Ambient light sensor
  • Proximity sensor

Glass also has software sensors which gives useful real-time data calculated from the hardware sensors. Some of the useful software sensors used in this project are:

  • Rotation vector
  • Linear Acceleration
  • Corrected gyroscope

The rotation vector software sensor is the most useful for this project application. The rotation vector uses the gyroscope, accelerometer and magnetometer data to set up a matrix describing the rotation of the Glass. This information is then used to get quaternion values for the orientation of the Glass. The orientation of glass is described in terms of yaw, pitch and roll angles in degrees. Yaw, also called azimuth, is the angle of glass around the Y-axis (in the figure below) relative to magnetic north and perpendicular to the horizon. This value tends to be prone to electromagnetic interference
(EMI) in noisy environments. Since the application of this project is focussed on SAR, there generally shouldn’t be a lot of EMI during operation. Pitch is the angle of Glass around the X-axis relative to the horizon. Roll is the angle of Glass around the Z-axis relative to the horizon. Pitch and roll values are reliable and are not prone to interference, they can therefore be used to replace the functionality of the yaw angle when there is interference. These values are sent to the Arduino via
Wi-Fi to control the angle of the gimbal.

The coordinate axis system of Google Glass
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FPV Racing – A New Sport

FPV Racing is a pretty new thing, not many people have heard of it, and most of the people who have are enthusiasts themselves. With that being said, if you have heard of it and you’re not an enthusiast, you should probably go see a doctor.

Instead of explaining in simple terms what it is, watch this video and you’ll have a pretty good idea:

There you have it, it’s basically the modern day equivalent of the racing that Annakin does in Star Wars, except it’s not as life threatening or expensive.

If you feel that you have done enough reading and want to get started, follow the Flying Robot link in the FPV Racing menu.

My love of remote control flying things runs deep into my veins. I have a very particularly intense love-hate relationship with remote control helicopters. I love flying them and I hate crashing them, something which happens way too often and a rebuild is ridiculously expensive.

With mini quad racers on the other hand, a crash is something you do when you want to get better, and most of the time the damage is propeller or two. It doesn’t really compare to the utter destruction at the crime scene of a helicopter crash, at all.

When I watched the video above the bug bit me instantly, I ordered parts from HobbyKing and waited a agonizing six weeks for them to arrive in Cape Town. I hurriedly slapped all the necessary parts together in a very sloppy build and Voila! I had my very first quadcopter.

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Myself and three other pilots in the first official South African FPV race ever!

The next few chapters of this love story is a dramatic tale of love and hate, albeit a lot of love, and very little hate…

3-Axis Gimbal Design

The initial design criteria of the gimbal was based around the selection of the gimbal payload, which is specifically tailored for search and rescue purposes. One of the most advanced and commercially available infra-red cameras on the market is the FLIR Vue Pro. This thermal imaging camera is perfect for SAR applications and is lightweight and small. With that being said, the gimbal has to be capable of taking modular payloads of various sizes. With this in mind, the gimbal was designed to accommodate cameras ranging from miniature sizes up to small SLR cameras weighing up to 700 grams. This set the engineering requirement for a specic brushless gimbal motor size. The motor specications are set by the manufacturer according to the maximum payload weight the motors can handle. This is a physical constraint owing to the rotational inertial properties of the camera as it sits on the gimbal.

The most important design consideration in a three-axis gimbal is the adjustable axis mounts which gives the gimbal the ability to maintain its payload on the centre of gravity. This design feature is clearly seen in the CAD drawing in the figure below. Each axis mount has adjustable fastening positions on two axes, allowing for six degrees of freedom adjustability of the payload, depicted as a hand-held camera in the assembly. Owing to the main focus of this project not being the design of the gimbal itself, but rather the control system of the gimbal, the preferred manufacturing technique was rapid prototyping. There are several methods of rapid prototyping but the most accessible and commercially available method is 3D printing by Fused Deposition Modelling. Most commercial or hobbyist built 3D printers operate by FDM.

CAD design showing the gimbal assemhly

The 3D printed parts printed well and can be seen in the figure below.The blue parts are PLA, a printing filament that is a lot easier to print with, but more brittle and not as strong. And the white parts are ABS, a filament that can be a real pain because it tends to warp as it cools down. Both materials were used to see how they hold up under stress and to take that knowledge into consideration in the final design.

3D Printed Gimbal Parts
3D Printed Gimbal Parts

The electronics that were chosen to be integrated into the gimbal were:

  • 3-Axis 32 bit Basecam Alexmos Gimbal Controller
  • DYS BGM 3608 – 70 Brushless Gimbal Motors
  • Arduino Mega
  • Arduino Wi-Fi Shield
The final gimbal assembly with all electronics installed
The final gimbal assembly with all electronics installed

Gimbal Control – The Principle and Application

Camera stabilizing gimbals have emerged with a boom. The first 2-axis gimbals were servo-controlled and mounted on multi-rotors to stabilize the video or FPV (First Person View) camera. Since then the technology has advanced drastically and brushless gimbal motors are a common sight on the market. The whole point of a gimbal is to keep a payload stable and in the same orientation independent of what its mounting platform is doing.

The video below demonstrates the principle:

That was a handheld brushless camera stabilization rig, I am designing a 3-axis brushless gimbal that is going to be mounted on a multi-rotor, most probably a quadcopter.

The idea behind the whole thesis is that it can be used for SAR (Search and Rescue) purposes. As a member of a SAR party, you want a unobstructed view of your surrounding environment, but a additional pair of eyes in the sky could be very helpful as well. Google Glass is one of the few available HUD (Head Up Display) platforms that gives you the ability to view a HUD screen whilst still having a unobstructed view of your surrounding. The screen doesn’t have to be very big if the camera payload is a infrared camera that looks for someone’s heat signature, something like that would be easily identifiable on the Google Glass’ screen.

The idea is to have a quadcopter that is flying above you, and you can control the gimbal simply by moving your head around. Additionally a position lock function would be very useful. Now this is no simple task, but it is something I would like to add to the whole system. The control algorithm will be based on a trigonometric mathematical model of the orientation of the gimbal, the heading of the quadcopter and the direction in which the gimbal is facing. All of this information will be provided by a GPS, Pressure sensor and compass, and the base controller will be a Arduino Mega 2560.

When a position lock is activated, the gimbal should face the camera lens so that the general area below the quadcopter stays in view, despite the movements of the quadcopter. Naturally the head movements of the controller will have no effective input to the system in this state. The controller then has a visible image of a certain area without having to maintain head control over the gimbal.

If this project is successful, it could prove to be a basis on which UAV (Unmanned Aerial Vehicle) assisted SAR operations are conducted and can be improved.

Gimbal Control by Means of Google Glass – A Undergraduate Thesis

3D Printed three-axis gimbal next to its Google Glass controller
3D Printed three-axis gimbal next to its Google Glass controller

When the time came to decide on a topic for my undergraduate thesis I was clueless. Fortunately for me I had the amazing opportunity to get involved with a awesome company called Simera Technology Group. There I had my first experience of a real-world engineering business environment.

My boss had recently purchased a pair of Google Glasses for the company to play around with and do development on, and it was on that topic that he suggested I try and integrate some form of head movement control with a gimbal and Google Glass. I was ecstatic about that idea, being presented the opportunity to play with Google Glass and to use it in my thesis seemed almost unreal. Nevertheless I was still petrified. I don’t know anything much about gimbals, despite being an avid multi-rotor enthusiast, and I know even less about Android development. But I knew it was a opportunity to show the world, but most importantly, myself, what I am capable of.

And so begins my journey with Google Glass, Android development, Arduino board, sensors and all kinds of other thingies that any geek, nerd or techy dreams about.

A 3-Axis Gimbal with a 32-bit Alexmos gimbal controller I was working on at Simera