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Unobstructed FOV | Since the OFS generates movement vectors based on differences between scans, it’s important that stationary objects like landing gear or wires remain outside of the FOV of the sensor. |
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Cable/Connector Access | It’s important to be able to probe signal wires and test the device, so cable/connector access is important |
Minimum height | Please refer to the manufacturer specification for minimum height that the optical flow will work, and ensure that the optical flow is always above that height when resting on the ground. This ensures that the OFS will continue to give good data all the way until landing. |
Parallel to the ground, facing downwards | This should be pretty self explanatory. When the drone is level, the OFS should also be level and facing towards the ground. |
In general, it can also be desirable to have tho OFS centered at the center of rotation of the aircraft, so that any rotation (yaw) can be rendered as pure rotation. If this is not possible, offsets for the optical flow sensor can also be added but they must be known to centimeter level. If you do not add offsets - the drone will attempt to rotate around the optical flow sensor, which may not be the natural center of rotation of the drone. This increases other sensor errors (especially GPS), and can cause unpredictable behaviour.
When pairing the optical flow with a rangefinder, it may be desirable to mount them close to each other (so data is more similar), but this is not a hard requirement.
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