Thursday, June 20, 2013

The first mission platform video

Just now beginning to tune both gimbals (and tune the assoicated dampening systems).

Here's some early test video from the first two gimbal systems:


Packing for the Bush

I had to sort through how to pack all the UAS components in a way that facilitated relatively easy transport, but also allowed for very quick forward deplopyment. The goal was a system that could be airborne within 5mins of arrival at any location. Step one was a smaller, more portable ground station. Here's V2.0 of the GCS:



Now, smaller, easier to carry, and designed in a water proof Pelican case.

Note the checklist to the right, now used before and during every flight, which was developed over several months of flight testing (i.e. anytime something nearly, or actually resulted in an incident or accident, the checklist was updated :) ).

Packing the UAV required some trade-offs. If the landing skids are disasembled, the whole UAV can fit in the single fairly small silver case to the right of this photo, but would take 15 mins to deploy (and introduce risk as it might be easy to miss a bolt while assembling in the field. I opted to use two cases for transporting the UAV:

The case in the right of this photo is an OEM design that can hold the complete UAV if the landing skids are disassembled

The top section of the UAV is packed in the OEM case. The landing skids are packed, completely assembled with one of three mission gimbal/camera combinations in the left case.
The UAV can be assembled, and completely pre-flighted, along with the GCS in under 5 mins.

 Batteries and associated peripherals got there own case for safety reasons. This case holds enough batteries for upwards of 3 hours of flight time!
The handheld controllers also have a dedicated case (along with room for spare cameras, lenses, etc)

Wednesday, June 19, 2013

Primary Mission Camera

The main mission cameras we're using are Sony NEX's  (NEX5s and NEX7s). I needed a very high quality gimbal that not only supported the NEX line of cameras, but had the capacity to handle bigger DSLRs and camcorders if need be. It was surprisingly hard to find an off-the-shelf BLDC-based solution, so I ended up have one custom fabricated.

Note the integrated avionics package mounted on the rear of the gimbal. It includes necessities like onboard HDMI to composite video conversion, and two separate DC busses to power the various components of the camera, gimbal and downlink systems.



Cameras, Gimbals, Mission Avionics


After several weeks of flight testing and tuning, I finally had a fully mission-capable end-to-end system, which included the UAV and both the Handheld Controller (i.e. RC controller integrated with handheld video) and a full blown Ground Control System.

It was time to start integrating the mission gimbals and cameras. The first of three camera/gimbal combinations was the GoPro with a direct drive brushless DC motor based Gimbal (using a SimpleBGC based gimbal controller).

To make it easy to swap camera/gimbal combinations in the field, I decided to dedicate a landing skip set (DJI calls them BiPods) to each camera/gimbal combination because BiPods can be swapped off the S800 with 90 seconds, with no tools required.

Also included are all the DC buses and video downlink subsystems (which vary from camera/gimbal combination to camera/gimbal combination).

The GoPro mount is the simpliest, although it still has two indepentend DC busses and a 5.8Ghz xmitter.

Heres the 1st BiPod, configured with the GoPro mount:




Developing the Production 'Copter

After proving out the end-to-end flight control SW, systems and procedures, it was time to begin integration testing with the mission platform, a modified DJI S800.

I had an S800 built by a local shop using an off-the shelf Flight Controller (a DJI Wookong) and did a bunch of baseline testing with it (endurance, climb rate vs battery charge, stability-vs-CG, etc, etc).



Next, I torn down the S800, rebuilding it with an Arducopter-based flight control system, and developing a custom mounting system that would ultilmately support the range of camera/gimbal/avionics packages I was planning to develop.  First step was getting an S800 flying with an APM. If you look carefully, you'll see the rudimentary camera gimbal and GoPro developed for testing both the platform, as will as the mounting system.



Battery Charging

It didn't take many sortes to realize battery logistics required some planning and development.

I decided to introduce field re-charging early in R&D process so I could develop processes and procedures, and ultimately a platform for managing batteries in forward deployments.

Even though my R&D copter used relatively small 3 and 4 cell batteries, I had a system built that was capable of rapid charging the 8000MaH monster batteries I suspected I would ultimately be using. I did this because I also needed more sophisticated computer aided battery charging tech early in the R&D process (for accurate performance and endurance characterization),  and figured I might as well design for the ultimate field deployment.

 Here's the 2000W portable dual charging system I had built. Not only was it helpful for my early testing (produces tons of useful data), but this portable system has the capacity to quickly charge multiple of the 6 cell 8000MaH monster batteries I eventually ended up using with the mission 'copter:


I combined this with an portable generator to enable multiple sortes while out on the test range (which has no access to power)
Developing Ground Control Infrastructure

Initial tests of the FW550+APM+Video downlink were run to understand both manual control, and rudimentary auto flight. Here's the handheld controller I used in these early tests, along with an attached video down link system I developed:






After early flight tests, it was time for more sophisticated automated flight tests, including guided (aka semi-autonomous) and fully autonomous modes.

I developed v1.0 of my portable Ground Control Station (GCS) to facilitate these tests. With integration of a bunch of peripherals via  internal power buses, video and USB, this GCS enabled in-flight control of all aspects of UAV operation. It provided real-time mapping of vehicle location (using Google Earth Maps), access to real-time telemetry data, video feed, flight plan programing, vehicle mode control, etc, etc.

Over the course of several weeks, I was able to gradually expand the mission envelope to include both semi autonomous, and fully autonomous (i.e. autonmous execution of multiple waypoint flight plans) operation of the R&D copter.


Some early video from field tests of the end-to-end platform....