System and method for a three-axis MEMS accelerometer
First Claim
1. A method of determining three components of an applied inertial force with respect to an orthogonal coordinate system, said method comprises the steps of:
- providing a semiconductor sensor chip having side 1 and comprising a frame element, a proof mass element and an elastic element mechanically coupling the frame and proof mass element;
selectively positioning only three stress-sensitive IC components integrated into three local areas of the elastic element;
orienting the orthogonal coordinate system such that X and Y axes are located in the plane of side 1 and Z axis is perpendicular to side 1;
applying a known inertial force to the sensor chip along X, Y and Z axes;
determining the matrix of offsets and matrix of sensitivities of the stress-sensitive IC components to the orthogonal components of the known applied force;
determining three orthogonal components of the unknown applied inertial force by solving with digital processing a system of three equations containing the three orthogonal components of the unknown applied force, matrixes of offsets and sensitivities of the stress-sensitive IC components to orthogonal components of the known inertial force vector.
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Abstract
A system and method for inputting motion measurement data into a computationally based device are provided. In a first version three-axis accelerometer determines components of an inertial force vector with respect to an orthogonal coordinate system. The accelerometer includes a sensor die made of a semiconductor substrate having a frame element, a proof mass element, and an elastic element mechanically coupling the frame and the proof mass. The accelerometer also has three or more stress-sensitive IC components integrated into the elastic element adjacent to the frame element for electrical connectivity without metal conductor traversal of the elastic element.
111 Citations
13 Claims
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1. A method of determining three components of an applied inertial force with respect to an orthogonal coordinate system, said method comprises the steps of:
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providing a semiconductor sensor chip having side 1 and comprising a frame element, a proof mass element and an elastic element mechanically coupling the frame and proof mass element; selectively positioning only three stress-sensitive IC components integrated into three local areas of the elastic element; orienting the orthogonal coordinate system such that X and Y axes are located in the plane of side 1 and Z axis is perpendicular to side 1; applying a known inertial force to the sensor chip along X, Y and Z axes; determining the matrix of offsets and matrix of sensitivities of the stress-sensitive IC components to the orthogonal components of the known applied force; determining three orthogonal components of the unknown applied inertial force by solving with digital processing a system of three equations containing the three orthogonal components of the unknown applied force, matrixes of offsets and sensitivities of the stress-sensitive IC components to orthogonal components of the known inertial force vector.
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2. A three-axis accelerometer for determining components of an inertial force vector with respect to an orthogonal coordinate system, the accelerometer comprising:
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a sensor die made of a semiconductor substrate comprising; a frame element; a proof mass element; an elastic element mechanically coupling the frame and the proof mass, wherein the inertial force applied to proof mass induces stress in the elastic element; more than three stress-sensitive IC components, which are used for creating more than one sets of three stress-sensitive IC components and integrated into local areas of the elastic element; a digital signal processing circuit for processing of signals from stress-sensitive IC components; whereby stress-sensitive IC components generate signals resulting from the stresses in the elastic element and at least one set of three stress-sensitive IC components is used for determining an unknown applied force vector components and the remaining sets of three stress-sensitive IC components are used for increasing the accuracy and reliability of the three-axis accelerometer. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of determining three components of an unknown applied inertial force with respect to an orthogonal coordinate system and increasing accuracy of three-axis accelerometer, said method comprises the steps of:
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providing a semiconductor sensor chip having side 1 and comprising a frame element, a proof mass element and an elastic element mechanically coupling the frame and proof mass element; providing more than three stress-sensitive IC components each integrated into a local area of the elastic element; orienting the orthogonal coordinate system such that two axes are located in the plane of side 1 and the third axis is perpendicular to side 1; applying a known inertial force to the sensor chip along the orthogonal axes for calibration; determining the matrix of offsets and matrix of sensitivities of all stress-sensitive IC components to the orthogonal components of the known applied force; creating sets of independent systems of three equations based on a number of non-repeating combinations from the number of stress-sensitive IC components in threes;
each independent combination of three stress-sensitive IC components corresponds to each independent systems of three equations;
each independent system of three equations contains three unknown variables corresponding to orthogonal components of unknown applied force, (1×
3) matrix of offsets and (3×
3) matrix of sensitivities of the corresponding stress-sensitive IC components to orthogonal components of the known inertial force vector;determining three orthogonal components of the unknown applied inertial force by solving at least one independent system of three equations; increasing accuracy of determining three components of an applied inertial force by solving other independent systems of three equations and by averaging the results of independent solutions. - View Dependent Claims (13)
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Specification