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Sep 17 2010

We get a new Tx/Rx and the Hexakopter flies waypoints!

Last week we had ordered a DX7 2.4 GHz Spektrum and an AR7000 DuaLink 7 channel receiver transmitter/receiver set from an online company. Unfortunately they had to send back their entire stock of Spektrum Tx/Rx due to a binding issue. On Monday Jonathan went down to Hobby Town USA and bought the set so that we could work on it during the week. By Tuesday morning, Jonathan had the transmitter charged so that we could work on binding it to the Hexakopter. First we had to pair the transmitter with the receiver, which we accomplished by powering the Rx with a small 5V NiCaD and pressing the bind button on the back of the Tx. Once the LED on the Rx glowed orange we tested it by hooking up a servo and moving the appropriate stick on the Tx.

Surprisingly, there was little work to do in order to connect the new receiver to the Flight Control board. We separated the main receiver from the external receiver. Then we clipped off one end so that we could solder the wires to the Flight Control board. Using a picture from the Mikrokopter Wiki we were able to solder the connections without a problem. Once we finished wiring the receiver we turned on the Hexakopter and the transmitter. However we soon found out via the “alarm clock style” buzzing from the Hexakopter that it was not receiving any signal. After a few minutes of trying to figure out what could be the issue, I changed the receiver setting on the Mikrokopter Tool from multi-signal (PPM) to spektrum satellite. This fixed the connection issue and allowed us to set up the altitude and GPS control.

Thursday we decided to test the Hexakopter and the new transmitter. First we tested the altitude control.  It was set up through the Mikrokopter Tool to be an adjustable altitude lock. We set this up so that once the altitude lock was set, you could adjust the height of the Hexakopter by moving the throttle stick up or down - a neutral stick meant that the Hexakopter was to hold position. After a few tries we managed to get the Hexakopter into altitude lock without a problem. We did notice however, that when the altitude lock was engaged near ground level (around 8 meters) the Hexakopter started to oscillate between around the locked height. We believe that this was caused by the propeller backwash and decided that any further flights would not engage the altitude control near the ground for extended periods. Afterwards we attempted to test the system's waypoint software. We started with the GPS lock mode, which held the Hexa at a position determined by when a 3-way switch on the Tx was moved to the middle position. The GPS lock mode had little issues and was easy to engage. However the main issue came when attempting to set waypoints. We could get it to fly to a single position by specifying a waypoint and switching the 3-way switch to GPS home mode but we were unable to get it to fly multiple waypoints.

Finally after some research on the Mikrokopter.us forums, we were ready to fly a set of waypoints. The issue was that we were not setting altitude lock and GPS lock before attempting to load. On Friday we set out to Herbert Run to test if the Hexa could fly a set of waypoints.