| 摘要 |
A number of methods and apparatus for measuring the position of an object relative to a reference are disclosed wherein a sensor for measuring the position of an object relative to a reference, comprises: a reference component and a displacement component, the displacement component being moveable linearly, rotatably, or both, relative to the reference component; and an input port for receiving a pressurized fluid, wherein: the reference and displacement components are configured such that a fluidic flow resistance through a predetermined flow path varies in a predetermined way as a function of a linear position, an angular position, or both, of the reference component relative to the displacement component; the reference and displacement components are configured such that the object can engage with the sensor in such a way that a linear displacement, an angular displacement, or both, of the object relative to the reference causes a corresponding linear displacement, angular displacement, or both, between the reference and displacement components; the sensor further comprises a detector adapted to obtain a measure of the flow resistance or of a change in the flow resistance and thereby measure a linear position, an angular position, or both, of the object relative to the reference; and the reference and displacement components are configured to allow detection of at least three different flow resistances associated respectively with at least three different linear positions, at least three different angular positions, or a combination of at least three different linear and angular positions, of the object relative to the reference. In an arrangement, a pressurized fluid is used to drive rotation of a cylinder around a piston and to bias the cylinder longitudinally. Ducts are provided in the cylinder and arranged so at to provide pulses of the fluid out of the cylinder through a reading port, the pulses being such as to uniquely identify the position of the cylinder relative to the piston and thereby of the object relative to the reference. |
