Abstract

The present invention discloses a position determination method and arrangement for a movable element (8) in relation to a stationary element. The invention applies markings (9) on the movable element (8) which are formulated as bar codes in uniform or non-uniform intervals along a bar- or cylinder-shaped movable element (8). The coding uses at least two bars and spacings between the bars, and both the bars and spacings may have a wide or a thin width. By comparing the widths of the parts and also incorporating halving of a part into the calculations, the arrangement is able to define a bit sequence for a sensed marking (9). The markings (9) may be arranged in a rising natural number fashion. When the sensed symbols behind the markings (9), the intervals between the markings and lengths of each marking are known, accurate positioning along the movable element (8) is obtained. In one embodiment, the wider part is 2,5 times wider than the thin part. The optical sensor (3) may apply incremental tracking in determining the characteristics of the sensed image when the movable element (8) moves in view to the stationary element. Application areas comprise e.g. hydraulic and pneumatic cylinders in general, industrial machines, vehicular applications, and furthermore, health, rehabilitation and gym devices for various users and patients.

IPC Classes  ?

• G01D 5/36 - Forming the light into pulses
• G01D 5/347 - Mechanical means for transferring the output of a sensing memberMeans for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for convertingTransducers not specially adapted for a specific variable using optical means, i.e. using infrared, visible or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
• G01D 5/246 - Mechanical means for transferring the output of a sensing memberMeans for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for convertingTransducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trainsMechanical means for transferring the output of a sensing memberMeans for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for convertingTransducers not specially adapted for a specific variable using electric or magnetic means generating pulses or pulse trains by varying the duration of individual pulses
• G01P 3/38 - Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light using photographic means
• G01P 3/68 - Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light