Apparatus for measuring inertial specific force and angular rate of a moving body
First Claim
1. Apparatus for measuring the specific force and angular rate of a moving body, by means of a plurality of accelerometers mounted on mutually perpendicular axes and cyclically driven by drive means in mutually perpendicular planes to produce output signals comprised of the specific force and angular rate, characterized in that:
- each accelerometer defines a force-sensing axis and a mass, each accelerometer is mounted for vibratory movement along a first vibration axis which is substantially perpendicular to its force sensing axis in its respective plane;
each accelerometer is vibrated by said drive means along its first axis;
each accelerometer is joined to a counterbalancing mass for counterbalancing the mass of the accelerometer; and
each accelerometer is connected to processor means for generating, from the output of the accelerometer and the angular rate "ω
" of vibration of the accelerometer, the specific force and angular rate vector of the moving body using the function "sgn cos ω
t".
2 Assignments
0 Petitions
Accused Products
Abstract
Apparatus for measuring inertial specific force and angular rate of moving body by means of a plurality of accelerometers mounted on mutually perpendicular axes, each accelerometer being mounted for vibratory movement along its respective axis. The apparatus further includes a drive for vibrating each accelerometer to produce output signals and a signal processor for deriving from the accelerometer output signals the specific force and angular rate for the respective axes. Enhanced performance is achieved by utilizing pairs of accelerometers vibrating along each axis combined with a preseparation circuit that separates the components of the accelerometer output signal having specific force information from components having angular rate information.
141 Citations
62 Claims
-
1. Apparatus for measuring the specific force and angular rate of a moving body, by means of a plurality of accelerometers mounted on mutually perpendicular axes and cyclically driven by drive means in mutually perpendicular planes to produce output signals comprised of the specific force and angular rate, characterized in that:
-
each accelerometer defines a force-sensing axis and a mass, each accelerometer is mounted for vibratory movement along a first vibration axis which is substantially perpendicular to its force sensing axis in its respective plane; each accelerometer is vibrated by said drive means along its first axis; each accelerometer is joined to a counterbalancing mass for counterbalancing the mass of the accelerometer; and each accelerometer is connected to processor means for generating, from the output of the accelerometer and the angular rate "ω
" of vibration of the accelerometer, the specific force and angular rate vector of the moving body using the function "sgn cos ω
t". - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. Apparatus for measuring the angular rate of a moving body by means of a plurality of accelerometers which are mounted on mutually perpendicular axes and which are cyclically driven by drive means in mutually perpendicular planes to produce output signals representative of the angular rate of the moving body, characterized in that:
-
each of said accelerometers has a force-sensing axis and generates an output signal "a" representing acceleration of the accelerometer along said force-sensing axis, each of said accelerometers being mounted for vibratory movement along a vibrating axis which is substantially perpendicular to said force-sensing axis in its respective plane; each of said accelerometers is vibrated along said vibrating axis in its respective plane at a predetermined frequency "ω
" by a tuning fork, said tuning fork having first and second prongs which are adapted to vibrate at a predetermined natural frequency, each accelerometer being mounted for vibratory movement on said first prong, said second prong including a counterbalancing mass to cause the two prongs to vibrate at said predetermined natural frequency, each tuning fork including an electrical driving member carried on one prong and an electrical pick-off member carried on the other prong, there being an electrical feedback loop from said pick-off member to said driving member to form therewith an electromechanical oscillator whose oscillations are sustained by said feedback loop; andsaid accelerometer output signals are converted by a processor to derive a signal corresponding to the angular rate vector "Ω
" from a product signal equal to "a sgncos ω
t" and the integral of said product signal over the cyclic period, and to derive the specific force vector "F" from the integral of "a" over the cyclic period.
-
-
16. An accelerometer assembly particularly useful for measuring the angular rate and specific force of a moving body, said assembly having a processor characterized by "a sgn cos ω
- t" where "a" is the output of the accelerometer and "ω
" is the cyclic frequency at which the accelerometer is driven, comprising;a supporting member; an accelerometer mounted on the body for vibratory movement along an axis of vibration, said accelerometer having a mass and being mounted on said supporting member to be rotatable about a rotational axis perpendicular to its axis of vibration; acceleration means for generating an output signal representing acceleration of the accelerometer along a predetermined force-sensing axis; drive means for vibrating said accelerometer along said axis of vibration at an angular frequency, said drive means oscillating said supporting member through a small angular motion about said rotational axis; and a counterbalancing mass, carried by said supporting member on the opposite side of said rotational axis of said accelerometer, for counterbalancing the mass of the accelerometer. - View Dependent Claims (17, 18, 19, 20, 21, 22)
- t" where "a" is the output of the accelerometer and "ω
-
23. An accelerometer assembly particularly useful for measuring the angular rate of a moving body, comprising:
-
two accelerometers carried by said moving body; accelerometer means for generating accelerometer output signals representing acceleration of each accelerometer along a predetermined force-sensing axis, each accelerometer being mounted for vibratory movement along an axis of vibration substantially perpendicular to said force-sensing axis; drive means for vibrating said accelerometers at an angular frequency along said axis of vibration; and signal processing means for separating from said accelerometer output signals an angular rate signal representing the angular rate of the moving body, said processing means including; (a) multiplying means for multiplying each of said accelerometer output signals by a zero-mean periodic function of said angular frequency; (b) rate integrating means, operatively connected to said multiplying means, for generating a rate integrated signal representing the integration of the resulting product of said periodic function and said accelerometer output signals over the period of said periodic frequency; and (c) rate sample means, responsive to said rate integrated signal, for generating the angular rate of said moving body. - View Dependent Claims (24, 25)
-
-
26. An apparatus for generating a signal representing the angular rate motion of a structure, comprising:
-
a first accelerometer including means for generating a first output signal representing acceleration along a first force-sensing axis; a second accelerometer including means for generating a second output signal representing acceleration along a second force-sensing axis; alignment means for aligning said first accelerometer with respect to said second accelerometer, such that said first force-sensing axis is substantially parallel with said second force-sensing axis; vibration means operatively connected to the structure and said alignment means for angularly vibrating said first and second accelerometers with respect to the structure at an angular frequency and in a direction substantially perpendicular to said first and second force-sensing axis; and signal processing means responsive to said first and second output signals for generating a rate signal representing the angular rate motion of the structure about an axis perpendicular to the plane of said force-sensing axes and said vibrating direction and a specific force signal representing the linear acceleration of the structure along said force-sensing axes. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
-
-
54. An angular rate sensing accelerometer structure of the type having a processor characterized by the mathematical function "a sgn cos ω
- t" where "a" is the output of the accelerometer and "ω
" is the cyclic frequency at which the acclerometer is driven so as to compute the angular rate and specific force of the body to which the acclerometer structure is attached, comprising;a housing; a shaft having an axis freely rotatably mounted in said housing; a support member secured to said shaft; two accelerometers each of which is secured to said support member; and vibrating means for vibratorily moving said shaft through a predetermined angular displacement about said axis. - View Dependent Claims (55, 56, 57, 58)
- t" where "a" is the output of the accelerometer and "ω
-
59. An angular rate sensing accelerometer structure comprising:
-
a housing; a shaft having an axis rotably mounted in said housing; a first support member; a first accelerometer secured to said support member; first flexure means for securing said first support member to said housing such that said first accelerometer can move in a direction normal to said shaft axis; a second support member; a second accelerometer secured to said second support member; second flexure means for securing said second support member to said housing such that said second accelerometer can move in a direction normal to said shaft axis; vibrating means for rotationally vibrating said shaft; and
,linkage means connected between said shaft and said first and second support members for vibrating said accelerometers along an axis substantially normal to said shaft axis. - View Dependent Claims (60, 61, 62)
-
Specification