I am experimenting with and hope to use a VL53LOX rangefinder to help with determining the altitude at which to flare in an auto-landing. On the bench I observe that the unit can deliver reliable distance of up to 110cm, or about one meter.
Arduplane has two related parameters:
RNGFND_LANDING. If set to 1, then the autopilot will use the rangefinder for both the landing approach and flare.
RNGFND_MAX_CM. The maximum reliable distance in centimeters that the rangefinder can measure. I set this to 100cm (1 meter) based on its performance on the bench.
I understand that the landing approach will start far above 1 meter in altitude.
During the landing approach will the autopilot use barometric pressure for altitude until the rangefinder delivers a value of 1 meter or less?
The plane will use for altitude what the EK2 will consider more reliable generally the barometer but it could be also the Gps .
In theory the AP will switch to rangefinder as primary altitude when during LAND mode EK2_RNG_USE_HGT condition will be satisfied and the message “rangefinder engaged at xx m” is recorded in the log.
Yes:
It comes preconfigured in binary output at 115200 Bauds and we can change the mode by issuing these commands through the Benewake console (http://benewake.com/en/down.html110) or using Realterm:
The command of standard output is 42 57 02 00 00 00 01 06 The command of pix format output is 42 57 02 00 00 00 04 06
The pixformat send clear ascii distances in meter and we can read directly this format x.xx (cr-lf). Within this mode it can be used with ArduPilot by choosing Lightware Serial @ 115200 Bauds
You might have to change the scale to Centimeter:
Modify output unit to mm output: 42 57 02 00 00 00 00 1A Modify output unit to cm output: 42 57 02 00 00 00 01 1A
Looking at the WIKI, I think the TFMINI has not sufficient range, most of use cases are above 6 Meter … When using a rangefinder for landing the altitude given by the rangefinder is used only in the landing approach and to determine the flare point, and is designed to allow the aircraft to more accurately follow the glide slope and to flare at the right time.