Abstract: A transmitter assembly includes a sandwich made up of a three axis transmitter, driven by a transmitter driver, mounted on a permeable attenuator with a spacer interposed between the transmitter and the attenuator. The attenuator is mounted on top of a conductive plate. A compensation coil is provided and driven by a compensation coil driver that energizes the compensation coil to optimize compensation for magnetic field edge effects. A number of individual compensation coils may be arranged about the periphery of the conductive plate or permeable attenuator. The individual compensation coils in the modification may be activated in tandem or individually to compensate for non-uniform magnetic edge fields caused by he non-symmetrical configuration of, for example, three transmitter coils or, for example, a square permeable attenuator rather than a circular permeable attenuator.

Abstract: In a first embodiment, a single linear array of bi-cell optical detectors is arranged with each bi-cell optical detector having a rectangular aperture located a prescribed distance above the surface of the bi-cell optical detector. In the first embodiment, in calculating the position of a point source emitter, it is understood that each detector receives light from the point source emitter at a unique angle different from the angles at which the other detectors receive light from the point source emitter. A plot of detector ratios is made by taking the best fit line through the ratios from each detector and the location of the point where the detector ratio is zero yields the point of perpendicularity between the emitter and the linear detector array. Another embodiment contemplates a three dimensional detector having three linear arrays of bi-cell detectors arranged at the periphery of a measuring space mutually orthogonal to one another.

Abstract: A method of measuring position and orientation of an object in a space in six-degrees of freedom includes a three axis transmitter transmitting a magnetic field to be received by a three axis receiver. The transmitter transmits a pulsed DC transmit waveform. The waveform is preferably a symmetrical square wave with distinct non-overlapping axes and signal processing is accomplished such that the integrator is reset at the start of the rising edge transient period, the coil output signal is integrated throughout the rising edge transient and steady state periods, and the integration result is measured at the end of the steady state period, for each axis. The result is dramatically enhanced signal to noise ratio. The timing of measurements is chosen to reduce eddy current distortion while providing improved compensation for drift of the sensor with respect to the Earth's stationary magnetic field.

Abstract: A method of measuring position and orientation of an object in a space in six degrees of freedom includes a three axis transmitter transmitting a magnetic field to be received by a three axis receiver. The transmitter transmits a pulsed DC transmit waveform. The waveform is preferably a symmetrical square wave with distinct non-overlapping axes and signal processing is accomplished such that the integrator is reset at the start of the rising edge transient period, the coil output signal is integrated throughout the rising edge transient and steady state periods, and the integration result is measured at the end of the steady state period, for each axis. The result is dramatically enhanced signal to noise ratio. The timing of measurements is chosen to reduce eddy current distortion while providing improved compensation for drift of the sensor with respect to the Earth's stationary magnetic field.

Abstract: A transmitter consists of a plurality of magnetic transmitters, each of which is substantially planar and made of a spiral shaped conductor. The result is a transmitter having a substantially uniform cross-sectional current density along the radial direction of the spiral from the center to the periphery. Near the plane of a given spiral, magnetic vectors produced by such a conductor arrangement have improved angular characteristics as compared to prior art systems. This results in a larger region with useful vector crossing angles and operation of the system is enhanced as compared to prior art techniques. The transmitters produce magnetic fields which have a monotonically increasing intensity as one approaches the center of the transmitter spiral from any given direction. This feature simplifies and increases the accuracy of sensor position determination.

Abstract: A transmitter assembly includes a sandwich made up of a three axis transmitter, driven by a transmitter driver, mounted on a permeable attenuator with a spacer interposed between the transmitter and the attenuator. The attenuator is mounted on top of a conductive plate. About the periphery of the conductive plate or the permeable attenuator, a compensation coil is provided that is driven by a compensation coil driver. The compensation driver energizes the compensation coil in a way to optimize compensation for magnetic field edge effects. In a modification, a number of individual compensation coils may be arranged about the periphery of the conductive plate or permeable attenuator, with the configuration of the compensation coils being designed based upon the factors set forth above, namely, the number and configuration of the transmitter coils, the shape of the permeable attenuator, and the configuration of the conductive plate.

Abstract: A patterned mask is located at a distance from a linear detector array. A point radiating source illuminates the aperture to cast an image onto the array. A computer is employed to identify frequencies in the frequency domain to determine the image scale and shift along the detector array axis. Determination of the magnification of the aperture image is made employing frequency domain techniques, the aperture pattern being re-scaled to match that of the actual image, so that determination of pattern shift can be made. A first embodiment of the present invention has two variations, one of which employs the use of multiple single frequency components and phase methodology, the second of which uses multiple single frequency components as well as a variable frequency component. In a second embodiment, a composite image is also used except that only one single frequency component is used in addition to a non-periodic function.

Abstract: A magnetic field position and orientation measurement system contains, confines and re-directs the magnetic field from one or more transmitters such that the fields are attenuated in areas outside of the operating volume in areas where metallic objects are commonly found. An attenuator made of a highly permeable material such as ferrite or mumetal may be placed on top of a conductive plate. The permeable attenuator may be as thin as 0.001 inches. on top of the permeable attenuator, a transmitter system is placed including at least three transmitters. In one embodiment, the transmitter consists of a PC board carrying the transmitter. The transmitter system, the permeable attenuator and the conductive plate, where used, may only be from ½ inch to ⅝ of an inch in thickness combined. The permeable attenuator may have a flat, planar configuration. Alternatively, it may be made to resemble, in cross-section, a cake pan having a flat central region with uplifted peripheral edges.

Abstract: A magnetic field position and orientation measurement system contains, confines and re-directs the magnetic field from one or more transmitters such that the fields are attenuated in areas outside of the operating volume in areas where metallic objects are commonly found. An attenuator made of a highly permeable material such as ferrite or mumetal may be placed on top of a conductive plate. The permeable attenuator may be as thin as 0.001 inches. On top of the permeable attenuator, a transmitter system is placed including at least three transmitters. In one embodiment, the transmitter consists of a PC board carrying the transmitter. The transmitter system, the permeable attenuator and the conductive plate, where used, may only be from 1/2 inch to 5/8 of an inch in thickness combined. The permeable attenuator may have a flat, planar configuration. Alternatively, it may be made to resemble, in cross-section, a cake pan having a flat central region with uplifted peripheral edges.

Abstract: Position and orientation determination uses stationary fan beam sources and rotating mirrors to sweep fan beams. In a first embodiment, a single motor has an elongated drive shaft with mirrors mounted on it, the reflective faces of which lie either in common planes or face in opposite directions. Fan beams are generated by stationary laser beam sources aimed at each mirror. As the mirrors rotate, each stationary source is reflected off a particular mirror and into a measuring space in a predictable pattern of movement. Electrical circuitry is provided with knowledge of the rotative position of the mirrors at any given time. A sensor attached to the object to be measured detects time of arrival of impinging scanning beams. At least one of the fan-shaped beams is skewed with respect to other beams, and at least two of the fan-shaped beams have origins sufficiently separated to allow accurate triangulation of the position and orientation of the sensor over various regions of the measuring space.

Abstract: A system for position and orientation determination of a point in space employs, in a preferred embodiment, three scanning laser beams that rotate at a high rate of speed within a prescribed space. At least two of the beams are polarized and a sensor with two or three detectors is located within the prescribed space. In each embodiment, at least one of the detectors has an unobscured, clear view of all of the scanning light beams at all times and at least another of the sensors is partially obscured. In the preferred embodiments, at least one sensor is polarized as well. Computer means is provided to facilitate calculation of position and orientation of a point within the prescribed space.

Abstract: A magnetic field position and orientation measurement system contains, confines and re-directs the magnetic field from one or more transmitters such that the fields are attenuated in areas outside of the operating volume in areas where metallic objects are commonly found. A thin barrier made of a highly permeable material such as ferrite or mumetal is placed on top of a conductive plate. The thickness of the permeable layer is from 0.01 inches to 0.25 inches while the conductive plate, preferably made of an aluminum alloy, may preferably be from {fraction (3/16)} of an inch to ¼ inch in thickness. On top of the permeable barrier, a rhombic three axis transmitter is placed. In the preferred embodiment, the transmitter consists of a PC board carrying the transmitter. PC boards having thicknesses varying from 0.03125-0.125 inches may be employed.

Abstract: A device is disclosed for measuring the position (location and orientation) in the six degrees of freedom of a receiving antenna with respect to a transmitting antenna utilizing multiple frequency AC magnetic signals. The transmitting component consists of two or more transmitting antenna of known location and orientation relative to one another. The transmitting antenna are driven simultaneously by an AC excitation, with each antenna occupying one or more unique positions in the frequency spectrum. The receiving antennas measure the transmitted AC magnetic field plus distortions caused by conductive metals. A computer then extracts the distortion component and removes it from the received signals providing the correct position and orientation output to a high degree of accuracy.

Abstract: In a sourceless orientation sensor, the sensor measures the three orientation angles azimuth, elevation and roll in a fixed reference three-dimensional coordinate frame. The sensor utilizes a three-axis magnetic sensor to measure changes in the Earth's magnetic field in order to determine the azimuth and roll (or elevation) angles after the elevation (or roll) angle has been determined by other means. A first embodiment utilizes a separate sensor to measure the elevation (or roll) angle in a fixed reference three-dimensional coordinate frame while a three axis magnetic sensor is used to measure the Earth's magnetic field. The azimuth and the roll (or elevation) angles are then determined from these measurements. A second embodiment utilizes a combination of a three-axis accelerometer to sense the Earth's gravity to measure the absolute elevation and roll angles for slow motions and a two-axis rate sensor to measure the azimuth and elevation velocities in the sensor frame.

Abstract: A hybrid motion tracker captures the motion of a person. Magnetic field sensors and optical sources are placed on a person, each located on different limbs. A fixed transmitter emits electromagnetic energy and infrared light is transmitted from the optical light sources to the fixed optical sensors. The magnetic field sensors sense the magnetic field and a computer calculates each sensor's position and orientation relative to the fixed transmitter. The optical system's Position Sensing Detectors measure the transmitted infrared light and the computer calculates the position and orientation of each optical light source. The position and orientation of each sensor is used to reconstruct the person's motion in real time, which is sent to a host computer. The computer utilizes the optical system which is more precise than the magnetic field system to compensate for the magnetic field system and thereby achieve higher accuracies. The system is a hybrid system using both magnetic fields and infrared light.

Abstract: The position and orientation of remote sensors is determined using pulsed magnetic fields generated from a fixed location. Pulsed magnetic fields are sequentially generated from a plurality of spatially independent components defining a source coordinate frame. The pulsed magnetic fields are sensed by a remote sensor having a plurality of passive field sensing elements. Eddy current distortions are sensed separately and subtracted by the system. The system measures the effect of metallic objects present in the environment and dynamically adjusts the measured values accordingly. The sensed magnetic fields, free of eddy current distortion, are used in order to calculate the position and orientation of the remote object. The system shortens the duration of pulsed magnetic fields and operates correctly at much further distances for the same energy output as compared to known systems.

Abstract: A system for the determination of the distance and orientation of an object carrying at least three light sensors from a fixed reference point when the object is irradiated by at least three modulated scanning beams of known angular orientation, and rotational frequency. Timing circuitry located in the control processor determines the time interval .increment.t , between successive interceptions of the object by each of the beams. Knowledge of this time interval and the scanning beams' relative positions and angular orientations permits calculation of the object's spatial coordinates. The optical beams utilized are fan-shaped in cross-section. The method of operation is also disclosed.

Abstract: The motion of a person is measured in real time using magnetic fields. A magnetic transmitter and a number of magnetic receivers are placed at different points on the person. The transmitter transmits magnetic fields sequentially from three orthogonal coils. The magnetic field is received at each receiver, which consists of three orthogonal coils. The computer resolves the sequential position and orientation coordinates from each receiver into the person's movement, relative to the transmitter, from knowledge of where each receiver is placed on the person. Other embodiments measure the transmitter's position and orientation relative to a fixed location outside of the person. The computer then resolves the position and orientation data into the person's motion relative to the fixed location outside of the person.

Abstract: A system for the determination of the distance and orientation of an object carrying at least three light sensors from a fixed reference point when the object is irradiated by two modulated scanning beams of known angular orientation and rotational frequency. Timing circuitry located in the control processor determines the time interval .DELTA.t, between successive interceptions of the object by each of the beams. Knowledge of this time interval and the scanning beams' relative positions and angular orientations permits calculation of the object's spatial coordinates. The optical beams utilized are fan-shaped in cross-section. The method of operation is also disclosed.

Abstract: Position and orientation of receiving antennae with respect to magnetic field transmitting antennae are determined. The transmitter consists of two or more antenna whose dimensions are large compared to the distance to the receiver. The receiver consists of two or more antenna that are sensitive to the type of signal transmitted. A computer is used to control the transmitting and receiving elements and to convert the received signals into position and orientation.