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The targeting system relies on the printhead, camera and and the vehicle to be aligned and square. In the current prototype the mechanical attachments were designed to allow some mobility for calibration and testing. However, in future systems methods ensuring the mechanical mounts are always aligned would be useful.
Target height
The system is calibrated at a certain height to align positions in the camera frame to where the spray system hits. However, objects at different heights (distance to the camera lens) will appear as different sizes and different positions relative to the calibration. In initial testing the height differential was low, so this was not an issue. However, if it is desired to operate in conditions with varying heights this will need to be addressed.
Potential solutions:
Use a telecentric lens to optically remove this effect.
Estimate height of objects (stereo vision or another sensor) and adjust for this in software.