Orientation tracking system and method
Inventors
Galea, Anna M • LeRoy, Kristen J. • Hirschman, Gordon
Assignees
Publication Number
US-8953154-B2
Publication Date
2015-02-10
Expiration Date
2032-07-26
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Abstract
An orientation tracking system including a first tracking system subject to drift. A second tracking system is configured to provide an output for calibrating the first tracking system to reduce the drift of the first tracking system. The second tracking system includes at least one inclinometer, each inclinometer including a light source adjacent one side of the inclinometer, a light sensor adjacent an opposing side of the inclinometer, and a light obscuring material within the inclinometer for obscuring the light between the light source and light sensor to indicate an orientation of the inclinometer.
Core Innovation
The invention is an orientation tracking system that includes a first tracking system subject to drift and a second tracking system that provides an output for calibrating the first tracking system to reduce that drift. The second tracking system comprises at least one inclinometer that includes a light source on one side, a light sensor on the opposing side, and light obscuring material inside the inclinometer which obscures the light between the source and sensor to indicate the inclinometer's orientation.
The system may include three orthogonally oriented inclinometers, each potentially implemented as a hollow toroid containing the light obscuring material, which can be a solid ball or a light absorbing fluid such as ink. The inclinometers can include one or more fluids and gases that aid in stabilizing the obscuring material. The light source may be a light emitting diode (LED), and the sensor may be a photodiode or phototransistor. The second tracking system's output is used to calibrate the first tracking system, which is subject to drift, thus enhancing overall accuracy.
The problem solved by this invention arises from the limitations of conventional orientation tracking systems, especially in challenging environments like flight decks where electromagnetic interference, line-of-sight requirements, or noise cause inaccuracies. Conventional systems relying on magnets, ultrasonic, infrared, video, or MEMS inertial mass sensors suffer from limitations such as drift, bulky components, slow operation, or interference. The invention addresses these issues by providing a drift-calibrating second tracking system using inclinometers designed with optical sensing to operate reliably in high electromagnetic environments and mitigate drift through continuous calibration of the first tracking system.
Claims Coverage
The patent includes multiple independent claims covering different embodiments of the orientation tracking system and method, each focusing on the integration of a first tracking system subject to drift and a second tracking system featuring inclinometers with optical sensing for drift calibration.
Orientation tracking system with optical inclinometer calibration
An orientation tracking system composed of a first tracking system subject to drift and a second tracking system that calibrates the first system. The second tracking system includes at least one inclinometer equipped with a light source on one side, a light sensor on the opposite side, and light obscuring material inside the inclinometer to indicate its orientation by obstructing the light path.
Inclinometer design featuring a hollow toroid containing light obscuring material
Each inclinometer includes a hollow toroid structure containing the light obscuring material, such as a solid ball or opaque fluid, to detect orientation optically by obstructing light between a light source and sensor.
Three orthogonally oriented inclinometers in calibration system
The second tracking system includes three inclinometers arranged orthogonally to each other to provide three-axis orientation information (roll, pitch, yaw) for improved calibration of the first tracking system.
Head mountable orientation tracking apparatus
A head-mounted system comprising both the first tracking system subject to drift and the second tracking system with at least three optical inclinometers, the latter configured to calibrate the former and reduce drift, suitable for tracking head orientation.
Method for orientation tracking involving first and second systems with optical inclinometer
A method comprising providing a first tracking system subject to drift and a second tracking system including at least one optical inclinometer with a hollow toroid containing light obscuring material, a light source, and a light sensor to calibrate the first tracking system and reduce drift.
The independent claims focus on an orientation tracking system and method that integrate a drift-prone primary tracking system with a secondary calibration system employing optical inclinometers designed with light sources, sensors, and light obscuring material within a hollow toroid. The claims cover configurations with one or multiple inclinometers arranged orthogonally, head-mounted apparatus, and the method of calibration to reduce drift.
Stated Advantages
Reduced drift in orientation tracking measurements by calibrating a drift-prone first tracking system using the second tracking system's output.
Reliable operation in high electromagnetic environments where conventional magnetic or ultrasonic tracking systems perform poorly.
Use of optical sensing in the inclinometers provides low power consumption and resistance to electromagnetic interference.
Enhanced accuracy and stability by combining data from inertial sensors with inclinometer outputs, enabling effective noise and drift compensation.
Documented Applications
Tracking the orientation of flight deck personnel in military environments to provide directional sound cues even when wearing hearing protection.
Immersive training simulators such as medical and driving simulators requiring accurate head or body orientation tracking.
Military applications requiring precise head orientation measurement in challenging electromagnetic environments.
Home entertainment gaming systems that need exact user location and orientation.
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