The application deals primarily with the guidance and positioning of a travelling automatic servicing device (16) relative to a plurality of operating stations (12), e.g. of a spinning machine, which are to be serviced thereby. Aspects of the communication of information between the device and the stations are also dealt with insofar as they are associated with the guidance and positioning features of the invention. The developments are applicable broadly to control of relative movement of parts other than those primarily illustrated.
