Is an Optical Flow Worth Fitting?

Archive
1

Hi,

I am scratch building my first autonomous hexacopter using APM 2.5. I understand the principles of the optical sensor but cannot find much information online regarding its performance when used with APM:Copter 3.1 and the 2.x hardware.

My flying will be outdoors in daytime. I would like to know if the position holding performance gains make it a worthwhile sensor to fit?

My current view is that the lack of info / videos suggest not - am I correct in this assumption?

Thanks in advance,

Zeke.

2

Hi Zeke,

Unfortunately PX4Flow is not currently supported by APM:Plane, APM:Copter, and APM:Rover firmware.

The PX4 team has information of how to use the sensor with PX4FMU and Pixhawk (no APM support) and the PX4 firmware:
pixhawk.org/modules/px4flow

3

I think, he was talking about the old optical flow sensor, not the PX4FLOW.

Sent from my Ainol Novo 7 Fire using Tapatalk

4

Oh sorry, this is the information we have in the wiki:
copter.ardupilot.com/wiki/optical-flow-sensor/

5

That Wiki link has gone dead, is there a wiki currently for APM optical flow?

Joel Silverman

6

@silvermanphoto,
If you are going to DIY you need to be a little more aggressive when searching for information and not give up so easily: http://copter.ardupilot.com/wiki/common-optional-hardware/common-optical-flow-sensors-landingpage/
Regards,
TCIII GM

7

TCIII,
can you confirm what last 3.2.1 APM version cover optical flow sensor? Ma be you know any custom version wit OF_loater covering shared for all??

8

The Optical Flow block estimates the direction and speed of object motion from one image to another or from one video frame to another using either the Horn-Schunck or the Lucas-Kanade method.
To compute the optical flow between two images, you must solve the following optical flow constraint equation:

I
x
u+I
y
v+I
t
=0
.

I
x
, I
y
, and I
t
are the spatiotemporal image brightness derivatives.
u is the horizontal optical flow.
v is the vertical optical flow.