There is provided a current sensor for monitoring electrical disturbances on an electrical circuit having an electrical conductor. The first and second vehicles are drawn together by retracting the extendable tensile element into the first vehicle until contact therebetween, after which roll axes of the first and second vehicles become substantially aligned responsive to a further retraction of the extendable tensile element into the first vehicle and a resulting tension in the extendable tensile element. The motors are supplied through power converters. Automatic threshold adaptation within multiple areas of the scene results in different possible thresholds in different areas based on the amount of segmentation noise in each area. Each page buffer is coupled to at least one bitline, the internal output line, and a data input line physically distinct from the internal output line, and configured to pull the internal output line to an output drive voltage in response to a bitline voltage on one of the bitlines coupled to the page buffer. The device can function in both a static mode and a traffic-adaptive mode.