Photos

Advantages

Compared to a quadrocopter with 4 rotors, an MK-Okto brings the following advantages:

• higher payload with up to 1kg (2.2 pounds)
• despite the higher payload no bigger (more dangerous) propellers or motors are being used
• redundancy: the Okto will still be able to fly with propeller damage or when it touches an obstacle.

Each motor is controlled by the electronics of the Okto.

Video vom MK-Okto

Motorization

• 8 * Robbe Roxxy 2827-34
• 8 * Propeller: 10" EPP
• Lipo 4S/3300mAh (flat make)

Guide to assembly

How is an MK-Okto built? Now some hints that could help with the assembly.

All images are clickable for a larger view

Frame

The frame basically consists of:

• Alloy arms (outriggers)
• shaped connection components and centerplates

Marking centerplates

First, the two centerplates should be marked, so that later on it will be obvious wher the front is.

The circular milliing is located at the lower left.

Mounting the 10mm bolts

On these (8) plastic bolts the brushless motor controllers will be installed later. Bolts are attatched with 8mm-plastic screws.

The bolts are mounted to the upper plate and point upwards.

Attatching the 15mm bolts

To these bolts the cam-mounting can be attatched later. Bolts are attatched with 8mm-plastic screws.

The bolts are attatched to the lower plate and point downwards.

Mounting the cover-holder

The dome will be mounted to these plastic pieces. They also serve as spacers between the plates.

Holders are fixed with 15mm plastic screws and nuts.

Preparation of the riggers

If the cables have to be inside of the arms of the Okto, holes might have to be drilled into the inner (shorter) arm. The latest version has the holes drilled already, so no further drilling is required.

The figure shows the position of the 6,5mm holes.

Mounting of the riggers

The 4 shorter riggers (arms) are fixed to the centerplate. The red riggers are for the front. Note the position of the holes on the bottom of each arm. If looking from above, the lower hole should be on the left side of the each arm. This will help with wiring later on.

4 15mm metal screws with "stop"-nuts are used for the inside. They have to be tightened well because of their decisive role for stability.

Now, 15mm rubber dampers have to be mounted. The FlightControl will be mounted onto those later on.

Wiring of the motor cables

For each of the motors, 3 wires with 52cm length (each) are used.

Tips:

• Mark the wires, so the corellation between motor and wire is not messed up during the process of wiring. Some motors come with colour-coded wires already attached.
• Stick or solder wires together before pulling them through. Or use a bent paperclip to pull each wire out of hole.
• if needed, attatch a string to the wires and pull it through first.
• Make a knot at the end, so the wire cant slip back out again.

Wiring of the buzzer cable

A small (0,5mm2), red and black cable goes through the rear rigger.

The buzzer is attatched here later and mounted to the rear Y-connector.

Y-connector

The Y-connectors are fixed with 15mm metal screws and stop-nuts.

Take care not to damage motor cables when putting screws through the riggers!

Velcro strips

This is used to attatch the batteries.

The stripe is fed through the designated slashes.

Electronics

The electronics and algorithms, running inside the microcontrollers, are the central component of a multicopter. Only through their sensors and fast adaptive controll flying is made possible.

It basically consits of:

• FlightControl -> "main cotroller with sensors" for the calculation of the copter's state

• BL-Ctrl -> fast drive and control of the brushless motors

• RC-receiver -> Interface between Transmitter (pilot) and FlightControl.

• LiPo-battery -> Powersupply

FlightCtrl

There still are some components which have to be attatched to the preassembled PCBs. In general, the preassembled version can be identified by its (red) colour.

"FC" is the abbreviation for FlightControl.

A circuit board (PCB) before and after assmbly of all the final parts (an example of the Flight-ctrl v1.2 shown):

The way and heading for the mounting of the FC is predefined:

• The arrow next to the switch has to point in direction of the front rigger (BL #1)
• horizontally
• uC (microcontroller) facing up!

Video about the assembly of the final parts (21,3MB)

Further information about the FC ME (MemsEdition)

BL-controller

The BL-Ctrl was designed especially for Mikrokopter.

Compared to common brushless controllers, the BL-Ctrl provides a fast data bus (i2c) to the FC and switches very fast to new target values. Common brushless controllers cannot be used.

The BL-Ctrls are adressed from 1-4(5-8) via jumpers (soldered).

Adress selection

Each motor requires a defined adress. That's why adresses from 1-8 are assigned.

With a BL-Ctrl V1.2, motor adresses can be set by a jumper (soldered).

rules:

General Infos about BL-Ctrl

BL-Ctrl V1.2

Adresses 5-8

Since the OktoKopter needs adresses up to 8, BL-Ctrls 5-8 need a special setup. In the set (from the shop), BL-Ctrls with special software are marked specially.

These BL-Ctrls are adressed by the following:

Power distribution board

The Okto distributor supllies all 8 BL-Ctrls with power and connects the i2c bus for communication.

The BL-controllers are mounted in the fitted slots and connected with cable bridges.

The TOP ist marked by a + (plus).

Arrangement of the BL-Ctrls

The BL-Ctrls are arranged as shown here.

• 

CAUTION: There is a small arrow on the power distibution board (gold). It has to be facing down and pointing to the REAR!

The microcontrollers of the Bl_Ctrl are on the TOP

Assembly of the bridges

8 bridges have to be assembled on the distribution board.

check for shortcut

The bridges may not have contact against each other or against plus or minus

Measure with a multimeter: against each other and against plus and minus it must have high resistance

Solder Elkos

The BL-Ctrls are connected via the wires of the Elko (capacitors). The Elkos are assembled from the top of teh distribution board.

There should be 2mm of air unter the Elkos (so the wire-ends are not touching the caps of the Elkos).

The Elko-wires are to be bent over and put (and soldered) through the + and - solder-pads of the BL-Ctrls.

MINUS (marked on each Elko) is on the INNER side (for inner Elkos) and on the OUTER side for outer Elkos.

a lot oh heat has to be used on the distribution board to make a perfect connection

Connecting the I2C-bus to the BL-Ctrls

The i2c bus (C&D) is connected via 2 silver wire-bridges.

The silver wire is stuck in the holes of the distribution board and bent over. After that teh ends of the wires are soldered to the "C" and "D" connection pads of the BL-Ctrls.

The distribution board should look like this now:

Connection wires of the power distribution board

The following wires are to be connected to the distributor:

• Battery plus and minus (2,5mm² + = red and - = black)
• I2C to FC: C and D (0,5mm² C = red and D = black)
• Supply FC (0,5mm² + = red and - = black)

always avoid possible shortcuts

I2C-bus connection

about 7cm 0,5mm²

Battery cables

about 15cm 2,5mm²

CAUTION: Ends have to be well-tinned so no tiny copper wires can stick off the strand.

Supply of the FlightCtrl

The power supply for the FC comes from the small + and - pads at the upper side of the power distribution board.

about 7cm 0,5mm²

Connection of motor wires to the BL-Ctrls

Now, the electronic components can be mounted to the frame

CAUTION: Motor 1 and 2 have to be in front!

The order is as follows:

• connect A = grey, B = blue, C = black on odd motor adresses (1,3,5,7) clockwise rotation

• connect A = blue, B = grey, C = black on even motor adresses (2,4,6,8) anticlockwise direction

If you don't use the standart motors, the order doesn't matter for now and might have to be changed later on during the motor test phase.

Connecting the FlightCtrl

Powersupply

Plus can be taken from behind the switch because the switch does not have to be assembled on the Okto. (it would only switch on/off the FC)

Later - the Okto will be switched on/off just by (un-)plugging the battery

Wires should be twisted a little to eliminate compass-errors comping from interfering fields.

Connection I2C to the FC

Attatchment of the RC-receiver

The receiver-cable is soldered to the 3 pads on the FC.

Connecting the buzzer

Mounting the FC

The FC is mounted in the way that the small arrow points to the front. plastic nuts can be screwed ontop of the rubber damper-threads optionally to place the FC a little higher.

The small arrow shows the front.

The electronics should look like this now:

Connecting and mounting of the motors

The motors are mounted with the screws they come with.

motor cables are soldered and covered with shrinking tube.

Battery wires

The battery cable is pulled through the loop on the centerplate.

The battery plug (deans male) is soldered to the wires (plus is marked on the plug) and the wires are covered again with shrinking tube for protection against shortage.

The battery might have to be (re-)configured with a female Deans-plug.

Here again - tin well for protection against short circuits.

The battry plugs are tightened with zip-ties.

DO NOT shorten the battery contacts!

Final mounting

Installing the FlexLanders (XL)

The landing gear is attatched by 20mm Screws (steel)

Installing the plate for a camera-mount

10mm-spacers are mounted under the lowest spacers

Another option would be to use 8mm vibration-dampers (the threads of the 15mm spacers might have to be shortened first)

To this plate a camera-mount could be installed later.

Installing the battery

The Battery is placed under the camera-plate and secured with Velcro strips

Starting Up

Prior to flight the Flight-Ctrl has to be set up as "Octo" - otherwise only 4 motors would turn on. To do that, the ALT-Key has to be held while clicking on "Settings" in the Mikrokopter-Tool. Then, the Mixer-Configuration "Octo.mkm" can be loaded

Informations about mixer-configurations

Make sure that the Undervoltage-setting is correct or you may damage your LiPo.

• Recommanded settings:

• 3s-Lipo: 9,9V
• 4s-Lipo: 13,2V

Safety

Read before using the Mikrokopter:

• Safety first

• Use and safety of LiPos

Flight and Handling

handling - turning on - calibration etc.

See also the Safety instructions

---

• KategorieAnleitung KategorieEnglish