Project Logs

Collapse

• Final product design outline

  Giovanni Durso • 09/28/2014 at 04:15 • 0 comments

  The goal of my project is to provide a system that consists of a docking cone with wires that your batteries including their respective balance leads will be connected to that mounts to the bottom of multirotors. Inside the cone there will be a wide angle webcam, sonar and a single board computer. Onboard computer connects to a flight controller over UART using mavlink packets and it is expected that the flight controller is using the arducopter firmware version 3.1 rc7 (or a version that has sonar support for your chosen flight controller). 

  (Prototype rendering of the system)
  Currently I am designing it for the F550 frame from hobbyking which is a knock off of the DJI H550 frame with a set of tall springy landing skids (they are useful for rough landings and have saved my hex  a few times) ,but the design can be easily adjusted to fit other frames by changing the parameters(height, width, angle and spacing of connection rings) of the docking cones.
  The system may not be suitable for small multirotors as it weighs approximately 500g, but this weight could be reduced in later versions as I am not optimizing for weight due to tight time constraints and prototyping.

  Integration with arducopter

  At a later date when the project is more mature I am going to make further modifications to the arducopter software to add in configurations to allow easier external control and integrate my offboard controller more into the firmware to allow easier integration for people who want to use this system.

• Current testing progress and results!

  Giovanni Durso • 09/28/2014 at 04:13 • 0 comments

  As part of my testing a rig has been set up in the front yard involving a rope between the roof and a tree in the yard which allowed me to test the copter repeatedly and ensure that any changes I made don't destabilize the craft or cause fly aways. Once the software has been proven to not cause problems and the copter had managed to perform its task while tethered a few untethered flights were performed in a reserve far away from people, power lines and buildings.

  
  It has been a slow and long process ,but finally I have managed to achieve a set of results that can be considered a working prototype system. The copter has been able to reliably detect and center itself over the target them bring itself down onto the target with a 10cm error outdoors which should be fine as the docking station is being designed to deal with that much error. Currently the system is a little slow with actuating itself over the target but this is past of slowly building up confidence in the system and taking it slow for safety reasons both for the copter and myself.
  

  Possible improvements:
  I can also improve my results when I switch over to a better state estimation when I can finish off the EKF design and I think velocity based control  for the positional control will work better than attitude based. As well as implementing a sliding mode controller rather than cascaded PID loops

• Prototype docking station design

  Giovanni Durso • 09/28/2014 at 04:04 • 0 comments

  In order to achieve the task of docking a multirotor for recharging a custom docking station had to be designed. Several designs were considered against the requirements in order to select the most appropriate.

  Read more »

• Visiual detection of landing target

  Giovanni Durso • 09/28/2014 at 03:46 • 0 comments

  Vision can be a very complex problem and when you add in the requirements and restrictions from the multirotor it can be very hard to find a suitable algorithm.

  Read more »

• Simulation of autonomous landing

  Giovanni Durso • 08/21/2014 at 02:23 • 0 comments

  Using the free vrep simulation environment and my access to matlab and simulink via the university the simulation model of the copter has been developed and I can work on designing vision based control algorithms without the risk of crashing copters.

• Flight tests of autonomous platform

  Giovanni Durso • 08/21/2014 at 02:07 • 0 comments

  The autonomous platform was assembled based on the design documents and all the electronics were validated in the lab. Once the system was confirmed to be working the platform was taken out to the ACFR test area on the Marulan farm.

  A number of tests were performed and the pixhawk running the arducopter firmware performed as expected.

  Preliminary testing of the visual system was started ,but the software integration requires more work and the addition of more failsafes to deal with fail cases

• Selection of onboard computer and autopilot

  Giovanni Durso • 08/21/2014 at 02:04 • 0 comments

  After considering the options avalible the three best possible solutions which are very close are the udoo, odroidx2 and the BBB.

  The odroidx2 is the most powerful processing unit by far it is almost twice as powerful as the udoo and almost 7 times as powerful as the BBB (assuming that all the cores are fully utilised) it also has twice and four times the offering of ram as the others.

  The downsides of the odroidx2 is that it does not have tha ardunio envrionment avalible on the udoo but since the FC(pixhawk) is receiving the sensor data it does not need many gpio pins itself. Also the selected sonar sensors have the option to use pulsewidth or serial transfer. It also has 4 uart, 3spi and 8i2c ports avlialbe so there is plenty of interfaces. The biggest downside is lack of good documentation and higher complexity to get things running due to having to deal with the linux to gpio interface.

  But odroid x2 + console cable + wifi = much more powerful processing for vision / control modelling

  With the pixhawk doing stabilisation/reading sensors and parroting the data over the uart

  The selected autopilot will be either an APM or a Pixhawk

  If the official APM is used then there is no real benefit to choosing it over the Pixhawk but if the arduflier or some other knock off version is considered instead than it may be worth it financially choosing it over the pixhawk

  The final selected autopilot is the pixhawk due to the higher processing power which allows an extended kalman filter to be implemented which can lead to better state estimation. Another benefit of the pixhawk is the extra ports avalible for external sensors to be integrated with the software framework

• Selection of multirotor platform

  Giovanni Durso • 08/21/2014 at 02:03 • 1 comment

  I have a lengthy design document for the selection and design of the copter system being used in my development. Some select sections have been posted here for documentation purposes and the document will be included with my project. 

  (link to lengthier design document)

  Read more »

View all 8 project logs