THEN they NEED to have ultrasonic sensors, activated at .. say .. 1/2-metre intervals, because LIDAR may be blind to float-glass that isn't at a right-angle to it, but SONAR isn't blind to sheet-glass.
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( the things might harm the hearing of animals, hence the limiting it to a chirp-every-1/2-metre idea: minimize noise-pollution that we are "blind" to, see? )