Achieving optimal performance with the HoverflyGPS requires a few simple steps before use.
You should first download and read the User's Guides for both the HoverflyPRO and HoverflyGPS. Get the Guides here.
Step 1 - INSTALL
Complete the installation of the HoverflyPRO and HoverflyGPS as specified in the User's Guides.
This includes updating to the latest firmware on BOTH the HoverflyPRO and HoverflyGPS. These boards need to be running the same version of the firmware. Get the Firmware Update Client here.
TIP: You need to mount the GPS antenna away from EMI sources as shown in the manual. We use a short mast made of fiberglass on the ERISTA and SCRIPTA.
Step 2 - CALIBRATE
Complete the three calibrations using the Setup Client. Get the Setup Client here.
TIP: Temperature and Accelerometer calibrations are performed by plugging the USB cable into the HoverflyPRO and switching the DIP switch to position 1. The temperature calibration can take a long time. You can use a hair dryer or heat gun approximately 0.5 meters away during this calibration to raise the temperature of the gyroscope quicker. YOU MUST be very careful not to induce vibrations from the blowing air or heat any components or wiring too high. Quicker is not always better.
TIP: Compass calibration is performed by plugging the USB cable into the HoverflyGPS and switching its DIP switch to position 2. You need to complete this calibration as far away from EMI interference as possible. We use along USB cable and go to the test field to do this calibration. Bring a friend and make him spin the aircraft around while you walk the computer around. You should spin around a few times (2 at least) even though the program says turn around once. Once is fine but twice is better. We will probably change the Setup client instructions.
IMPORTANT: You should use a USB cable without a ferrite bead to do the magnetometer calibration. The ferrite bead can cause anomalies.
Step 3 - TUNE PRIMARY GAIN
Tune the Primary gain in gyro only mode (Auto-Level off) so that you are just below the value when the craft seems to twitch or oscillate rapidly. The value in the Setup Client for Primary gain is irrelevant. You should concentrate on the feel by adjusting the gain channel (typically the Gear channel). This is explained in the HoverflyPRO manual. Once this the Primary Gain is adjusted land and switch to Auto-Level mode and set its Gain to be equal to the Primary Gain.
Step 4 - TUNE AUTO LEVEL
Complete this on a calm day with little or no wind.
Power the craft with all switches in the off or "0" position. This puts the craft in gyro only mode with no features activated. Lift off and get the craft stable. Activate Auto-Level (AL) and trim the craft. Land in AL and unplug the battery. Plug the battery in again and lift off with AL off. Get the craft stable again and turn on AL. If you need to trim again, you will need to land, power cycle, and repeat. Continue this process until the craft does not drift except with the wind when AL is activated.
Step 5 - TEST POSITION HOLD
Starting with the battery unplugged switch all switches on the transmitter to their OFF position or "0". Plug the battery in powering the craft. Wait until the GPS LED is Green or even better Blue.
Lift off and move away about 10-20 meters. Gain altitude to 10-20 meters and activate Position Hold (PH). Give the craft time to find its new position. Most of the time the GPS location and the craft need to converge on a location which can be up to 3 meters away from where the PH was activated. Adjust the throttle for altitude (unless you have previously tuned the Altitude Hold gain and have now activated it). The craft should stay in a 3 meter diameter circle (the resolution of commercial GPS).
Step 6 - TEST RETURN-TO-HOME
Move the craft many meters away from the launch position (where you arm the HoverflyPRO). Activate PH and wait a minute. Now activate Return-to-Home while maintaining altitude with the throttle. The craft will quickly approach the Launch location and then slow down when near. The craft will then slowly return to within 3 meters of the launch position.
If the craft is circling around the PH position then you will need to check the mounting location of the GPS antenna and more importantly re-calibrate the compass. Most of the the time the circling affect is caused by the compass bearing having an error.
Another reason for circling or poor PH and RTH performance is AL trim. You may need to re-calibrate the accelerometers
More tips will be added over time.