Discussions

I have my APM1 based UAV working now, it's been quite a journey so I thought I would post some of what I learned since many others are probably going to be buying APM1 now that it's half price (right after I bought mine of course :-)

I'm writing this since I know many of you are not very experienced with R/C, let alone something like APM.  The wiki instructions are well written and helpful, but they may lack details needed by people with little experience.

First lesson is, be very careful what you order from 3DR since you can't change or cancel the order once it is placed.  Do your research carefully first, better yet connect with others in your area who are experienced and seek their advice.  I ordered the APM1 by mistake.  Since it appeared at the top of the list, I wrongly assumed it was the latest and greatest.  But, it's been all worthwhile in the end :-)

I would advise ordering the best GPS that is compatible with your board, the magnetometer, and the 3DR telemetry kit right from the start.  Trust me, you're going to want the telemetry.  It doesn't cost much and it's really cool!

Also, probably goes without saying, but if you have no experience with R/C, best to get yourself a basic plane and learn to fly R/C first, before even trying to work with APM/Arduplane.  And yes, start with fixed wing first.  Fixed wing is a lot more forgiving than copters.  If you choose a good slow-flying plane, you will have a lot more time to react if something goes wrong than you will with a copter.

When setting up your R/C, one thing that bites many people is putting a connector on LiPo batteries.  Work with only ONE wire at a time.  It's very easy to short the wires, causing big sparks and damage to the battery (and your ego :-)  This goes for all of the electronics.  Check polarity and connections CAREFULLY before applying power.  If you get things reversed, you can fry the board and ruin your whole day.  This has *never* happened to me of course :-)

Assembling and soldering the board (I bought the kit) isn't difficult, but if you've never soldered before,  practice on some dummy parts before touching APM.  If you're intimidated by soldering, you might just want to pay the extra $50 and buy the assembled board.  You will need a fine tip soldering iron and fine solder.  You may want to start with just the basic board, bring it up first and then add the magnetometer and battery monitor.

First thing to check after assembly and before power-on is the CLI switch.  See below.

For whatever reason, my board was shipped with the switch in the AFT position (to the left in the picture).  APM will not connect with MP (Mission Planner) in that position, it needs to be forward (in the flight direction, as shown in the picture).

Before proceeding, you will need a complete R/C setup with speed controller, LiPo battery, receiver and servos.  It is safest to start without a motor connected to the speed controller, or if you must, make sure the motor and prop are securely mounted and the plane is weighted down and the prop clear before proceeding.  Once you power up APM1, it can suddenly cause the motor to go to full throttle.  Hopefully I don't have to paint a picture of how ugly that can be if you're not prepared for it :-)  Lightweight objects can be sucked into a propeller which can cause damage.  Don't run the motor without a prop, it isn't good for them.

Download and install of the MP software shouldn't pose any problems.  However, getting my system to recognize APM via the USB connection was at first difficult.  On some systems, other USB drivers may interfere with the APM driver.  Best bet is to use a system with as little add-on hardware and software installed as possible.  If you can't get it to recognize APM, try a different computer.  In my case, I had installed the PX4 Toolchain before MP, and there were apparently conflicts.

Use the APM Planner with MAV 1.0.  I still don't know why the MAV 0.9 version is still available, but it is likely because of some backward compatibility issues.  My setup has worked fine with MAV 1.0.

Pay close attention to the COM section of the MP interface, make sure the COM port and baud rate are set correctly before you attempt to connect.  Baud rate should be 115200 unless you have a *very* old computer.

I did not see any problems with the upload of the firmware once the COM port issues were resolved.

Connecting the R/C equipment should not pose any problems.  Again, if you're not familiar with R/C equipment, get familiar first.  None of it will make any sense if you don't know anything about channel assignment and servo connections.  Follow instructions on calibrating your radio, this is very important.

Hopefully once you connect you will see the MP interface come alive, yay!!!  Test stabilize mode to make sure everything is working.  VERY IMPORTANT -- CAREFULLY check the control directions in stabilize mode.  I've been flying R/C for over 30 years and my first flights had the rudder reversed.  What you get is DE-stabilize mode in that case :-)  The direction the control surfaces move is not really intuitive like it is for normal R/C.  For normal R/C, when standing behind the plane, left stick should move the rudder left, for example.  In stabilize mode, if you roll the fuselage to the right, the rudder should move to the LEFT to bring the model back to straight and level flight.  Elevator/pitch control is a bit more intuitive.  Move the nose down and the elevator should move UP to compensate.  Double/triple check this before you fly.  Recheck it any time to make changes, no matter how minor.  Better still, check it before every flight as they advise.

I wouldn't advise messing with failsafe mode until you get the basics working, maybe not even then :-)

Flying

Check and re-check everything already mentioned.  Level the plane carefully.  I use a bag of rice to set the fuselage on, allowing me to level it on any surface.  Get a cheap 2-axis level from the hardware store, glue it onto a small flat piece of wood, plastic or metal big enough to sit flat on a part of the plane that is level with the wings and fuselage.  Check both Manual mode, doing a normal R/C radio check, and Stabilize mode throws and directions.

Make sure you have the 'flight mode' control on your transmitter ready at hand.  Especially for first flights and first attempts to transition from manual to stabilize or any other mode, keep a finger on that switch at all times.  Let me repeat that, AT ALL TIMES!  Until you get everything dialed in, you may get unexpected results at any time.  Things may start out OK, but then go sour in an instant.  If you have your finger ready on the switch, you can instantly switch back to Manual mode and recover the aircraft.  I have had just about everything conceivable go wrong, but I have not crashed yet because I have followed this rule.

Hopefully your first flights will be uneventful :-)  I have noticed that it is difficult (if not impossible) to get the plane to fly perfectly under Stabilize or FBW modes.  In particular, my plane would consistently lose height under FBW mode.  I wouldn't worry about this too much, as long as the plane is basically stable. KEEP YOUR FINGER ON THAT SWITCH, even after Stabilize/FBW seems to be working.  I still occasionally got weird results at times and had to go back into manual just before disaster :-)  My plane behaved much better on the first RTL attempt, it was quite stable and did exactly what it is supposed to.  Follow the instructions on tuning, not much to add there.

Adding Sensors

For me at least, adding the magnetometer wasn't really noticeable.  I didn't experience any problems.  Just follow the directions.  The battery monitor was a different story.  I chose to use the on-board battery monitor.  It works, but it has issues that have to be worked around.  Long story short, keep the battery monitor disconnected during APM power-up and initialization.  Once the lights stop blinking, you can connect the monitor circuit to the battery and everything should work.

The telemetry worked as described, but be very careful about the connections.  Check each end carefully.  Since the red wire is in the center, it is easy to reverse the connector.  Follow the instructions, but there is a step omitted at the end.  You have to 'connect'!  May be obvious to some, but many people get to the end of the instructions (myself included) and say, "OK, what now???" :-)  Remember the COM/baud setting interface?  If everything is working, you should now see two COM ports on the drop-down.  Choose the new one, which you should get after the ground-side telemetry board is connected to your PC via USB, and hit "Connect".  You should see the usual connection messages and the flight display come alive as normal.

Mission Planning

The instructions for this are good, just a few things to add.  Once you're ready to try setting waypoints and using AUTO mode, go into "Flight Planner".  Click on the little double arrow at the bottom of the screen to see the Waypoints inteface:

You will now see a list of your waypoints as below.

My first attempts to fly waypoints were successful.  However, one of the first things I tried was the JUMP command, which failed miserably.  Still don't know why this doesn't work, but don't expect it to.  You can manually cause the same thing to happen.  Go back to the "Flight Data" interface.  You will want to get familiar with the tabs across the lower-left window.  Go to "Actions", here you will find many useful controls once you are in-flight.  This is where the telemetry becomes crucial.  If you have telemetry, you can change the waypoints or issue new commands while the aircraft is airborne.

To manually do a JUMP (go back to WP1 and start over), use the "Restart Mission" button.

On the upper left, the "Do Action" button and the drop-down menu to its left allow you to cause the aircraft to "Loiter" or "Return to Launch" (RTL) at any time. To return to the waypoints programmed, you have to hit the "Auto" button and then "Restart Mission".  If in doubt, the waypoint display (The 0>0 display to the immediate right of the arrow above) on the HUD should confirm what the plane is trying to do.  This shows "distance to next waypoint" > "waypoint number".

In the "Flight Data" screen, right click on the map.  You should see the pop-up menu as shown below.

Try "Fly to Here".  The aircraft should head for the point indicated.  Great stuff!!!

Hopefully this should help get you started.  I know some of this is basic stuff, but trust me, some will find it useful :-)

Be safe and have fun.

Cheers,

Gary