As I have said in my first post, MAVs need flight controllers to stabilize them in flight. These flight controllers have complex algorithm's that run recursively. Usually these systems only take advantage of the four propellers to stabilize the system. Until one of my professors showed me a blog post about a new stabilization technique for MAVs, I also thought using propellers was the only way to stabilize MAVs.
Like insects, this new system changes the center of mass of the system to stabilize the craft. This technique was developed by a team in the LIMBS Laboratory of Johns Hopkins University. The team of researchers who came up with this system, first examined how moths stabilize in flight. below is a video showing how a moth uses his moth to move the center of mass to have a stable flight.
Researchers used the same idea to stabilize a quad copter. To make an abdomen that has enough mass for the quad copters, the team of graduate students made a gimbal for the battery. Below is a picture of how the final design looked like.
Notice the battery attached with a servo below the copter. Credit Alican Demir.
With the battery being placed on a servo, the group of researchers were able to stabilize the quad rapidly. A video of the final design is in this blog. After I noticed this new technique for stabilizing in flight, I realized that many more MAVs will begin to have this technology.
Welcome to my blog! In this blog I am going to share interesting research on the development of Micro Air Vehicles (MAVs). I myself am also doing some design and research on MAVs therefore in the future I will also post about my own design and research results.
In my first post I will be briefly talking about the history of quad-copters (from the family of MAVs). I will end with talking about the flight controller that I use.
De Bothezat Helicopter, Edison National Historic Site Archives
Although most quad-rotors we see today are unmanned, there was a time when these copters were designed specifically for human use. After the first airplane design was successful, the government allocated some money on vehicles that could take off and land vertically. George de Bothezat received funding for his design in the early 1920s. A picture of the built design is show on the right. Quad copters are 6 degree of freedom systems. Although the De Bothezat helicopter flew in 1922, the government shut down the program because it was really difficult to control a quad copter. In the beginning of the video below you can see a De Bothezat Helicopter flying.
As you can see, the De bothezat helicopter is not very stable and it keeps on turning counter clockwise around it's z axis. Today, two of the propellers, in every quad copter, turn in the opposite direction to keep the craft stable. If all four turn the same way, then the forces would add up turning the whole copter. Below is a picture that shows the direction of the propellers on a quad copter.
Ardpilot.com
Since the size of electronics have become smaller we can now mount flight controllers on top of small quad copters. These flight controllers solve the difficult stabilization equations and make it easier for us to control the quads. This article gives a very good introduction on flight controllers. It shows the different flight controllers that are available and their advantages.
Ardupilot.com
For my design I chose to use the arducopter flight controller. The ardupilot flight controller is an open source board that has a very active developer community. This developer community fixes bugs with the current firmware, adds new features and releases the new firmware. The ground station Graphical User Interface (GUI) also gets updates and looks very modern and runs fairly fast. A picture of the ardupilot board is shown on the right. Some of the features of the flight controller is listed below.
Arduino compatible with an integrated Atmega chip.
3 axis gyro and accelerometer
Barometer to sense the altitude
4 Mb datachip on board to log flight details
GPS and telemetry inputs.
On one of my next posts I plan to explain the GUI and its features.
