Article directory
25.1 Testing and Setup of Optical Flow Sensors
25.2 Cheerson CX-OF Optical Flow
25.2.2 Connecting to the autopilot
25.2.3 Additional instructions
25.3 Hex HereFlow Optical Flow Sensor
25.4 PX4FLOW Optical Flow Camera Board
25.6 UPixels UPFlow Optical Flow
25.7 ARK Flow Open Source Optical Flow and Distance Sensor
Preface
Copter , Plane and Rover support optical flow sensors. These are camera modules that use ground texture and visible features to determine the aircraft's ground speed.
Select a link below for information on available sensors.
25.1 Testing and Setup of Optical Flow Sensors
There is too much space, so I will write another introduction:
25.2 Cheerson CX-OF Optical Flow
The Cheerson CX-OF optical flow sensor is lightweight and low-cost and can be used to improve horizontal position control, especially in GPS signal-deprived environments.
25.2.1 Where to buy
The sensor is available from several retailers including Banggood.com and AliExpress . Search for " CX-OF spare parts " to find more retailers.
These alternatives have also proven effective:
These alternatives may work, but have not been proven:
25.2.2 Connecting to the autopilot
The optical flow sensor should be installed on the bottom of the rotorcraft with the camera lens facing downwards. The side of the sensor marked " V2.0 " should be facing the front of the aircraft. The picture above is incorrect because the autopilot 's arrow is pointing down, while the sensor's " V2.0 " label is near the top.
Connect the sensor's TX and VSS (aka GND ) pins to one of the autopilot 's serial ports. In the picture above, the sensor is connected to the Pixhawk 's Telem2 port.
Connect the sensor's VDD (aka VCC or 3.3V ) to the 3.3V supply. The Pixhawk switch port is used in the picture above , but the power pins of the SPKT/DSM port can also be used.
Set FLOW_TYPE = 4 .
If using Serial2/Telem2 , set SERIAL2_PROTOCOL = 18 ; if connecting to other serial ports, use the corresponding SERIALx_PROTOCOL parameter.
25.2.3 Additional instructions
As with the PX4Flow sensor , using this sensor's autonomous modes (including Loiter and RTL ) requires a rangefinder.
FlowHold does not require the use of a rangefinder.
The sensor has been successfully tested at a height of approximately 40m .
Performance can be improved by setting sensors position parameters . For example, if the sensor is mounted 2cm forward and 5cm down from the frame's center of rotation , set FLOW_POS_X to 0.02 and FLOW_POS_Z to 0.05 .
25.2.4 Testing and Setup
For setup guidelines, see Optical Flow Sensor Testing and Setup .
Please note that the recommended EK2_FLOW_DELAY or EK3_FLOW_DELAY value for this sensor is 80 .
25.3 Hex HereFlow Optical Flow Sensor
There is too much space, so I will write another introduction:
25.4 PX4FLOW Optical Flow Camera Board
There is too much space, so I will write another introduction:
25.5 OpenMV for optical flow
There is too much space, so I will write another introduction:
25.6 UPixels UPFlow Optical Flow
There is too much space, so I will write another introduction:
25.7 ARK Flow Open Source Optical Flow and Distance Sensor
There is too much space, so I will write another introduction: