A position encoder uses a track encoded with a pattern of bit-widths in accordance with a sequence. The sequence may be any sequence having unique subsequences, and may be a pseudo-random noise (PRN) sequence such that each N-bit subsequence occurs only once on the track. Sensors detect transitions between the bits and bit-widths as the track moves with respect to the sensors to provide in-phase and quadrature-phase pick-off signals. The pickoff signals are summed and absolute value thresholded. The absolute value thresholded sum signal is sampled when the quadrature pairs are in the "00" or "11" quadrants, and latched when the sum signal goes high to distinguish between wide and narrow bit widths. The latch is shifted into a shift data register for use in determining the position of the encoder track. In the case of a PRN sequence having a length of 2.sup.N bits, the position may be an absolute position when the number of valid bits in the shift data register is at least N. The position may be an incremental position when the number of transitions detected is less than N.
LEDs are driven by pseudorandom number sequences unique to the LEDs, respectively, and emit light having light intensity change corresponding to their respective pseudorandom number sequences. The light from the LEDs enters a PSD. The PSD outputs currents having levels corresponding to intensity of bright spot images occurring at incident positions of the light and the incident positions. Matched filters subject the outputs of the PSD to correlation operation processing, thereby separate outputs corresponding to each LED, and then supply the outputs to a decoding circuit. The decoding circuit generates an output signal for each light source photographed, which signal comprises information on the position on a plane of incidence of the PSD and an identifying number of the light source. The positions of the LEDs are determined by using the output signal.
It is an object of the present invention to provide a moving body system which can determine a moved position of a moving body such as a guided vehicle or a stacker crane wherever it is on a moving path, which can stop the moving body anywhere, and which can quickly move the moving body to a stopped position. The present invention provides a moving body system including a guided vehicle 1 moving along running rails 2, 2 constituting a moving path and a detected member 20 laid along the running rails 2, 2. The detected member 20 includes a large number of mark members 21, 21, . . . in a direction in which the guided vehicle 1 moves. The guided vehicle 1 includes a first detecting sensor 11 and a second detecting sensor 12 which detect the mark members 21, 21, . . . of the detected member 20.
It is an object of the present invention to provide a moving body system which can determine the moving position of a vehicle, stacker crane, or other moving body wherever on a moving path having a branching portion or a joining portion the moving body is, the system being able to precisely stop the moving body at any position and enabling the moving body to move fast to a stop position. A moving body system includes a vehicle 1 moving along running rails 2, 2 constituting a moving path having a joining portion and a detected member 20 laid along the running rails 2, 2. The detected member 20 includes a large number of mark members 21, 21, . . . in a direction in which the vehicle 1 moves. The vehicle 1 includes a first detecting sensor 11 and a second detecting sensor 12 which detect the mark members of the detected member 20.
