- History of the Mikrokopter
- Mikrokopter - A rough Overview
- Why MikroKopter?
- Some theory
- Extra functions
- Practicing with the Simulator FMS
- The MikroKopter is ready. What next?
- Calibration before first use/modification or new firmware
This page gives you a rough overview about the Mikrokopter (MK).
History of the Mikrokopter
On 24.10.2006 Holger Buss and Ingo Busker brought MK to life with a great community of Mikrokopter pilots. Only 6 months later, the Mikrokopter hovered steadily, like an "airnail" and flew agile through the air like a bird.
In a short time frame further, components were added. By now it is even possible to run half-autonoumos flights. The Mikrokopter is strong. It can carry the weight of a camera or sensors. For more sportive pilots the Mikrokopter offers enough agility to fly loops (over pitch and roll-axes).
Mikrokopter - A rough Overview
Notice: before your first flight, make sure you have a RC model casualty insurance!! While reading you might have some questions. The fastest way to get answers are:
read the FAQ
search the Forum
look at the MikroKopter Replicas
- open up a thread in the forum
ask in the IRC.
Why should I become a member of the MikroKopter community? This question ist not easy to answer. There are many projects that deal with Quadrocopters and all got their advantages and disadvantages. A big plus of the Mikrokopter-scene is the great support. It has helped many beginners. Maybe the right question is: Why not?
A frequently asked question is: how can a quadrocopter fly at all? Actually, it is quite simple...
There are two different propeller-rotations. The front and back propeller turn clockwise, while the left and right propellers spin counter-clockwise. To hover, all propellers rotate at the same speed. When doing so, the forces between the clockwise props on one hand, and the counter-clockwise props on the other hand, are balanced out. This makes the quadrocopter hang steady in the air.
To be able to fly in one direction, the quadrocopter will be brought out of balance. The speed of the propeller that opposes the desired direction is increased. This makes the quadrocopter tip over in a certain direction. Example: to fly forward, the back-propeller has to turn faster. This is called "pitch" or "nick". In this MK community "nick" is the preferred name for the forward/backward-movement. Left and right movements are called "rolls".
The opposite (vertical) axe is called "yaw", but in German and Dutch it is referred to as "gieren". To be able to yaw you need a force to turn around. This force is created by changing the speeds between the forward/backward props and the left/right props. Example: to yaw clockwise, the forward/backward propellors will turn faster and the left/right propellers will slow down a little. This makes the quadrocopter turn clockwise, while maintaining the same height.
For a stable flight, you need a controller. The main task of such a controller is to make sure that the Mikrokopter remains steady in the air. It uses data from several sensors and calculates the speed for each individual propellor and it also compensates for external disturbances like wind. The controller is programmed with (open-source) software that holds all logic to keep the Mikrokopter balanced.
The components of a MikroKopter will be explained below. For more information, click the links.
Things you might need if you start from scratch
Here you find a list of all required items.
The Flight Control
The Flight-Control (Flight-Ctrl) is the main board of the MikroKopter. It contains the main processor and all the sensors that are necessary for a stable flight.
Of all sensors, the rotation speed sensors are most important. The software uses them to determine the position in the air and to compensate for external influences. For every axis (x,y and z) a rotation speed sensor is needed, so three sensors all together. Usually these rotation speed sensors are called Gyroscopes or Gyros and they measure changes in degrees per second.
Another sensor is the acceleration sensor. It senses the acceleration in all of the three axis. The vertical acceleration sensor is also able to measure the angle of the mikrokopter towards the earth. Usually they are referred to as Accellerometers or ACC. You can fly without them, but with these sensors you are able to automatically get the MikroKopter back to level flight. This way you can let go of the joysticks and the MikroKopter will stay at its position. Without these sensors, the Mikrokopter will keep on flying in a prescribed angle. This kind of flying is called "Heading Hold".
A height sensor can be placed on the Flight-Ctrl as an option. This gives you the ability to keep flying at the same height all the time.
When hooked up to a PC, the Flight-Ctrl can be read and set with the MikroKopter-Tool.
There are two different versions of Flight-Ctrl and here are the differences:
All other features are equal.
FlightCtrl - More Information
en/FlightCtrlManual - Building manual for Version 1.0
FlightCtrlManual_V1_1 - Manual for building manual for Version 1.1
The Brushless Controller
In total there are four Brushless Controllers (BL-Ctrl) needed for the MikroKopter. Each controller controls one brushless motor. Brushless motors don't use brushes for energy-distribution to the rotor. In contrary to the motors with brushes, the magnets are rotating while the coils do not. That's why you can't use a DC current, AC current with precise pulses is needed to drive the motors. This AC current is provided by the BL-Ctrl.
A standard Brushless Controller will not work in a MikroKopter. The BL-Controllers are connected to the main board with a bus system (I2C) and each controller is given a unique address that is used by the main processor to communicate with the BL-controller. It is possible to control the BL-controller with a standard RC-receiver. PPM signal input is available (but not for the use in a Mikrokopter).
- Controller: AVR ATMEGA8 of Atmel
Placed with six 60 Amps MosFets
integrated current measurement
- Current limitation at the DC current-side
- Designed for approx.110W at 11.1V or 150W at 14,8V (10A contineous)
- Peak current approx.220W at 11.1V or 300W at 14,8V (20A peak)
- two LEDs (Okay and Error)
- Battery voltage sensing with low-voltage detection
- Software is totally in C
- As setting point either the rpm can be controlled or set (per PWM)
- several inputs for setting point
- Size (L x H): 43mm x 21mm
The actual version 1.1 is available as emty PCB or with all components in place. The older version 1.0 isn't available anymore. The old version needs a separate firmware for each controller with separate addresses. Since version 1.1 the addresses are adjustable via jumpers (shortcircuits).
BrushlessCtrl - The most important information
BL-Ctrl_Manual - Manual for version 1.0 with pictures; also usable with questions about version 1.1
BL-Ctrl_V1_1 - tips for version 1.1
In general, a Quadrokopter needs four brushless motors. The following motors have proven to be usable and function very well with the BL-Ctrl:
Two Clockwise (CW) propellers and two CounterClockWise (CCW) propellers are needed.
- Front = Motor #1 and Back = Motor #2 clockwise
- Right = Motor #3 and Left = Motor #4 counterclockwise
When starting and stopping the Mikrokopter, you can observe the direction of each propeller. Beginners should buy a few extra props; the standard EPP1045 (10" length, 4.5" travel after 1 complete turn) which most of us use usually break easily when crashing into hard objects.
- EPP 1045
- X-Ufo Props
The receiver receives the orders given by the pilot and converts them to electrical signals which in turn are read by the Flight-Control. MK require a receiver with a summing signal. This signal contains information about all the channels sent by the transmitter and it must be available as an output on the receiver to feed the FlightControl mainprint. This summed signal will be processed by the Flight-Control software into separate channels and will be used to drive the MikroKopter.
To control a MikroKopter you will also need a transmitter. Any commercial RC-transmitter with at least four channels will do. Each axis of a joystick is seen as one channel (f.e. up-down). So two joysticks with two movable axis each are sufficient.
More channels can be controlled with turning or moving potentiometers, or by flipping switches. These can be used to control height, switch lights or control camera-movement.
Visit these links for more info on transmitters:
The frame is the 'skeleton' of the MikroKopter. There are almost limits to your imagination. The motor-motor distance can vary between 35 cm and 60 cm, depending on motor and propellor size. It is advisable for beginners to start with a standard 40cm frame made of aluminium square profiles. 40cm is the distance between the center of each motor (which means the legs are a bit longer, eg. 42 cm).
en/Frame-building - Small overview about building a frame.
Uusually Lithium-Polymer batteries or LiPos are used as the main power source. These batteries differ from other types because of their light weight and high capacity. Handling these batteries is not without danger, so some rules have to be kept in mind. LiPo's need a special charger because the charging procedure differs a lot from other types (like NiCad and NiMh). The cells should not be overcharged, neither should they be discharged to deep.
To keep the charge difference between cells to a minimum, a balancer must be used. This balancer might be integrated in the charger, or a separate balancer should be attached. All LiPo-packs feature a connector for a balancer.
For a MikroKopter LiPo-packs with three or four cells are used. They have a voltage of 11,1 V or 14,4 V.
- Commonly advised:
.Advisable: LiPo 3s 11,1V ca2100mAh, 20C
LiPo-Akkus - More information about LiPos and how to use them.
Currently there are some extra functions available for the MikroKopter:
GPS - GPS-Compass-Modifications of some MK-Users
Everything you need to build a MikroKopter. Most of it is available at the MK-Shop.
Here you find a list of all things you need to start from scratch
FlightCtrl (main board)
- 4x BL-Ctrls (Motor controller)
1x SerCon (for programming and setting)
4 Motors Motoren
- Receiver and cristal (see available channels )
Frame materials (f.e. alu-square-profile and CenterPlate)
Propeller EPP1045 (at least 10 sets)
- Propellor adaptor or Propsaver (fitting the motor)
LiPo-battery (advisable: 2 pieces)
- Mounting material (screws etc.)
Cables for the cabling between Flight-Ctrl and the 4 BL-Ctrl
Connectors (see Steckverbinder), tiewraps, shrinktubing and some more...
Other buy-once articles:
- Transmitter and cristal (see available channels)
LiPo-charger with balancer
Practicing with the Simulator FMS
The Flight Model Simulator (FMS) is a free software program, which can be used to learn flying before using the "real" MikroKopter.
A basic MK configuration doesn't fly like a helicopter. It hoovers much more stable in the air. The big fun with simulation software is that it doesn't frustrate you too much when your virtual MK crashes. It is even possible to use your own RC-transmitter for control using the PC's soundcard (microphone input).
The MikroKopter is ready. What next?
Your MK is ready and you're dying to take your first flight? This flight can easily end up in the ground.
Please take your time and a look at Mikrokopter Learning to Fly.
Calibration before first use/modification or new firmware
Perform ACC Calibration:
It is *very* important that the MK is as horizontal and still as possible, shim it up so the arms are perfectly level, then program EEPROM by moving left stick to upper right corner. (max throttle + max right yaw)- you'll hear audible confirmation.
ACC only needs to be calibrated once, after that you can start from an embankment or sloping surface without problems. The saved values will be loaded at every bootup.
Perform magnetic Calibration:
Safety is important to protect you and your enviroment.
Here you find the Safety instructions and checklists before start
Always switch on the transmitter first, then the MikroKopter. The MikroKopter has to be positioned level on a stable ground. The green LED of the Flight-Ctrl lights up, the red Led is off and the buzzer is quiet. The green Leds of each BL-controller is lit, and the red LEDs are off. If the buzzer beeps, the received signal is interrupted or the battery voltage is low.
At power on, all four motors and controllers will be briefly tested. This test routine causes the propellers to move a bit at low speed, so your fingers will stay on when you accidentally touch them. A funny 3-tone frequency check completes this test, meaning all 3 coils of the motor are alive and are not short-circuited.
- Is the spinning direction of each motor correct ? (front/back: clockwise, left/right: counter-clockwise)
- Are the correct propellers installed on the correct motors? (yes there is a difference between clock and counter-clock propellors)
Is the attribution of the channels set correct in MikroKopter tool?
Are the led-indications on the FlightCtrl and all four Bl-Controllers correct?
Calibrate sensors and choose Setting
Note: the throttle should not be inverted: minimum throttle means stick points to pilot = lowest throttle. Now you have to calibrate the sensors: press the throttle/yaw joystick in the upper left corner for a while, until the buzzer beeps and the green Led turns off. At this moment:
the controller considers the actual gyro-sensor values as "levelled". This calibration is needed because the sensors are temperature sensitive and the movement of each axis of the acceleration sensor can differ a bit. The MikroKopter will always try to maintain the position it has at the moment of calibration when flying, because it accepts that position as level. That means, the more it is out-of-level, the more correction will be needed by the pilot to maintain position. While performing the calibration, the actual "Setting" (amount of beeps represents the setting-number) can be choosen by the Nick-roll-joystick as follows:
2 3 4
1 x 5
x x x
Explanation: NickRoll joystick Left Centre = Setting1; Left Up=Setting2, Centre UP=Setting3, etc. Again: keep the throttle-yaw joystick upper left and the Nick-Roll joystick at the same time to any of the positions mentioned above. It also works the other way around, first choose the setting with Nick-Roll, keep the joystick there and calibrate with throttle-yaw. (old-Papa) Starting from version 0.6x, you can upload calibration data into the Eeprom with throttle-yaw upper right. At next calibration with throttle-yaw upper left, calibration data will be downloaded from the Eeprom. This way it is possible to start flying from surfaces which are not spiritlevel.
For beginners it is advisable to start with setting 3. In this setting, the joystick movements are not too sensitive.
To switch motors on, move the throttle-yaw joystick into the lower right corner, until the motors are spinning. At a given throttle-value the level-controlling function of the FlightCtrl will start functioning. To switch motors off: press throttle-yaw into the lower left corner for a while, until the motors stop.
In the picture below the joystick positions and settings selection are visually explained:
NOTE: to avoid launch failures, caused by wrong attribution of channels, you should mount (attach) Mikrokopter on the ground before your first take-off and check if the channel attribution is correct. This is absolutely necessary when you flashed new software, played around with the settings via bluetooth etc. It will save you a lot of props
Do not to hold the Mikrokopter with your hands - you could be injured by the rotating propellers. For instruction video on how to test without propellers look here http://youtu.be/PU7uL55piz4
Because of the high joystick sensitivity, a beginner should set Nick and Roll to "exponential". Refer to the manual of your transmitter on how to do this. Beware of the sensitivity so keep joystick movements small! Choose a sufficiently large area for your first flight, take off swiftly (don't stay to long near the ground, this causes a lot of instable turbulences) and try to keep your MK steady at approx. 1 meter height. Concentrate on the heigth first. Land gently when the Mikrokopter turns in a wrong direction. When you're confident to keep the MikroKopter at a certain height, add some directional steering by trying to keep the nose pointed away from you by yawing the MK. Concentrate on height and yaw first. Only when you are happy with the results, start using the nick/rol joystick. Move your MK a bit further away. Land. Gently take-off. Come back. Land. And celebrate your first successful flights!
A Mikrokopter is not a toy! Responsibility, patience, the willingness to read the documentation and a casualty insurance are all required before any flying is done. Please consider this very seriously. Never start without any insurance. Make sure to apply to your local governmental rules, especially when flying near airports. Never fly above people and stay away from children.
More about insurances can be read in this FAQ.
In chatrooms you can meet us at:
- Channel #mikrokopter
- Channel #mikrokopter-en (english)
Mikrokopter Wiki Team Channel
- Channel #mk-wiki
You find the chat under this adress: http://forum.mikrokopter.de/chat/chat.php
also look under Shops