Method and apparatus for dynamic 6dof measurement
OwnerViswanathan Madhavaninventor
Life of this patent
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Abstract
A method and apparatus is disclosed that modulates the position of one target tracked by a position measuring instrument, measures the path of the target, fits the parameters of a mathematical representation of the time varying path to the path of the target measured as a function of time, and obtains the position, orientation and velocity of the object on which the apparatus is mounted. Key aspects of the modulating nest and the improved method for determining the best fit mathematical representation of the path of the target resulting from the combined effect of the modulation and the motion of the object are disclosed.
Claims36
A method for measuring six degrees of freedom of an object (all three positions and all three orientations), and for directly estimating its velocity, over a time interval, by
- using one position measuring device to measure a time sequence of positions of one target over the time interval,
- using a modulating nest affixed to the object to vary the position and/or orientation of the target with respect to the object over the time interval, along a modulation path,
- causing the sequence of points measured by the position measuring device to lie on a static target path when the object is stationary, said static target path being modified into a dynamic target path by the movement of the object, said dynamic target path being mathematically represented as a function of spatial variables and of time, said mathematical representation containing parameters that are related to the position and orientation of the static target path and the velocity of the object,
- identifying the values of the parameters of the mathematical representation of the dynamic target path that best fit the measured path segment,
- inferring the position and orientation of the static target path as well as the average velocity of the object over the time interval, from the parameters of the best fit mathematical representation of the dynamic target path, and
- obtaining the average position and orientation of the object, from those of the static target path.
An apparatus comprised of a device containing a fixed path and a means for holding and moving a target in a highly repeatable manner along this path,
- which is used to modulate the position of the target, which is recorded by a position measuring device,
- and a processing means for analyzing the measured path using software that takes as input a mathematical representation of the geometry of the path and identifies parameters of the best fit representation of the path,
- for the purpose of determining the position, orientation and velocity of any object to which the apparatus is affixed.
A system, comprising
- at least one modulating nest with at least one rigid path and means to move at least one target along the one or more paths
- and at least one processor that is either the same as that of the at least one position measurement system, or communicatively linked to it
- a memory communicatively coupled to the processor and holding an instruction set executable on the processor to cause the system to
- maintain, in the memory device, mathematical information about the geometry of the at least one paths
- maintain, in the memory device, one or more sets of instructions for determining the rigid body transformation of the path that best fits the points measured by the position measuring system,
- evaluate the position and orientation of the path by fitting the path to the measured positions of the target, and
- evaluates, records and displays the position and orientation of one or more other points on the object based on their known spatial relationships to the modulating nest.
Dependencies are inferred from the claim text.