公开(公告)号：US5361635A

公开(公告)日：1994-11-08

申请号：US46338

申请日：1993-04-12

Applicant: James R. Woodruff

Inventor： James R. Woodruff

IPC: G01P15/08 ,  G01P15/13 ,  G01P15/18

CPC classification number: G01P15/0894 ,  G01P15/131 ,  G01P15/18

Abstract: A servo accelerometer permits compliant suspension with a pair of flexures by using a plurality of tunnel current position sensors each respectively associated with a corresponding pair of electrostatic drive electrodes. The tunnel current position sensors and the electrostatic drive electrodes are positioned to control undesired movement of the proof mass about a first axis which is normal to the input axis of the accelerometer. In another embodiment, three tunnel current sensors and three pairs of drive electrodes are used to control movement of the proof mass about the first axis and a second axis.

Abstract translation: 伺服加速度计通过使用分别与相应的一对静电驱动电极相关联的多个隧道电流位置传感器来允许具有一对挠曲的柔性悬架。 隧道当前位置传感器和静电驱动电极被定位成控制证明质量块围绕与加速度计的输入轴垂直的第一轴线的不期望的运动。 在另一个实施例中，使用三个隧道电流传感器和三对驱动电极来控制证明质量块围绕第一轴线和第二轴线的运动。

公开(公告)号：US4365512A

公开(公告)日：1982-12-28

申请号：US216194

申请日：1980-12-15

Applicant: James R. Woodruff

Inventor： James R. Woodruff

IPC: G01P7/00

CPC classification number: G01P7/00

Abstract: An angular rate instrument adapted for mounting to a given object for measuring the rate of turn of the latter is disclosed herein. This instrument utilizes an angular accelerometer to sense angular acceleration to which the instrument is subjected and a circuit for integrating the difference between this signal and a reference signal to produce an integrated output signal corresponding to the rate of turn of the object. The angular rate instrument also utilizes a null circuit for producing the reference signal in response to and dependent on low frequency error signals which appear at the output of the signal integrating circuit. The null circuit uses a capacitor to provide the reference signal and means for maintaining the charge on the capacitor during power interruptions so as to prevent losing the reference signal as a result of such interruptions.

Abstract translation: 本文公开了适于安装到给定对象以测量后者的转弯速度的角速度仪器。 该仪器使用角加速度计来感测仪器所经受的角加速度，以及用于积分该信号与参考信号之间的差的电路，以产生对应于物体的转动速度的积分输出信号。 角速率仪器还利用零电路来响应并依赖于出现在信号积分电路的输出端的低频误差信号产生参考信号。 空电路使用电容器来提供参考信号，以及用于在电源中断期间保持电容器上的电荷的装置，以防止由于这种中断而丢失参考信号。

公开(公告)号：US06269698B1

公开(公告)日：2001-08-07

申请号：US09340559

申请日：1999-06-28

Applicant: James R. Woodruff

Inventor： James R. Woodruff

IPC: G01P1510

CPC classification number: H03H9/24 ,  G01P15/097 ,  G01P2015/0828

Abstract: A mechanical resonator having interconnected vibrating beams and counter balances whereby transfer of energy from the vibrating beams is essentially eliminated.

Abstract translation: 具有互连的振动梁和平衡器的机械谐振器，从而基本上消除了来自振动梁的能量传递。

公开(公告)号：US5503018A

公开(公告)日：1996-04-02

申请号：US987947

申请日：1992-12-08

Applicant: Brian L. Norling ,  James R. Woodruff

Inventor： Brian L. Norling ,  James R. Woodruff

IPC: G01P1/00 ,  G01P15/08

CPC classification number: G01P1/003 ,  G01P15/0894

Abstract: A tunnel current position sensor has a first sensing electrode coupled to a compliant beam for providing force relief to the sensor. The beam is connected in fixed relationship with a first object. A second sensing electrode is coupled to a second object. The compliant beam elastically deforms to prevent damage resulting from crashing of the electrodes.

Abstract translation: 隧道当前位置传感器具有耦合到柔性梁的第一感测电极，用于向传感器提供力释放。 梁与第一物体固定关系。 第二感测电极耦合到第二物体。 柔性梁弹性变形，以防止由于电极的撞击造成的损坏。

公开(公告)号：US4779463A

公开(公告)日：1988-10-25

申请号：US3483

申请日：1987-01-13

Applicant: James R. Woodruff

Inventor： James R. Woodruff

IPC: G01P15/13 ,  G01P15/08

CPC classification number: G01P15/132

Abstract: A servo type accelerometer including a main support base, a pendulum assembly and a servo arrangement is disclosed herein. The pendulum assembly includes a pendulum and means supporting the pendulum for limited rotational movement through a normal resting plane about a fixed axis within that plane and relative to the base in response to and as a result of the pendulum being subjected to acceleration forces normal to the resting plane. The servo arrangement cooperates with the pendulum for monitoring the presence and magnitude of these acceleration forces, if present. A particular feature of the accelerometer disclosed resides in specifically designed flexures for supporting the pendulum and a technique for preventing these flexures from being placed in a state of compression and possibly being damaged thereby. Another feature resides in the way in which the entire pendulum assembly is supported to the base and still another feature resides in the particular way in which the torque coil forming part of the servo arrangement is mounted to the pendulum.The present invention relates generally to accelerometers and more particularly to a number of different improvements in a pendulous type of servo accelerometer with a flexure suspension.The typical pendulous type of servo accelerometer comprises a main support base, a pendulum assembly and a servo arrangement. The pendulum assembly may be divided into three parts, a pendulum, a support member for the pendulum which itself is supported by the main support base, and means for attaching the pendulum to its support member in a way which permits limited rotation through a normal resting plane about a fixed axis within that plane and relative to the support base. This movement is in response to and as a result of the pendulum being subjected to acceleration forces normal to the resting plane. The servo arrangement cooperates with the pendulum for monitoring the presence and magnitude of these acceleration forces, if present.More specifically, as the pendulum tends to move away from its resting position in response to the acceleration forces being monitored, a torque coil, which forms part of the servo arrangement and is mounted to and is part of the pendulum, and which is immersed in a magnetic field, is energized with an electric current sufficient to prevent the pendulum from moving from its normal resting plane. The amount of current necessary to do this proportionate to the acceleration forces being monitored and therefore by monitoring these currents the acceleration forces themselves can be monitored.In the typical flexure-suspended pendulous type of servo accelerometer described above, its pendulum is attached to the support member, in a manner which permits limited rotational movement, by means of a pair of spaced-apart, flat flexures which lie within the normal resting plane when the pendulum is at rest and which are sufficiently resilient to permit limited rotational movement of the pendulum. While these flexures are perfectly satisfactory for their intended purpose so long as the only acceleration forces applied to the pendulum are those normal to the resting plane, that is, the acceleration forces being monitored, other acceleration forces, for example, those directed along the axis of the pendulum normal to its pivot axis can place the flexures in a state of compression. Unless this is prevented, the flexures could buckle, crumble or otherwise break as a result of these compression loads.It is an object of the present invention to provide an uncomplicated and yet reliable way of preventing the support flexures of the type recited immediately above from being placed in a state of compression when their associated pendulum is subjected to non-monitored acceleration forces that would otherwise place the flexures in a state of compression. As will be described in more detail hereinafter, in a preferred embodiment this is accomplished by providing a secondary flexure associated with each primary support flexure. Each secondary flexure is designed to be placed in a state of tension when the pendulum is subjected to these undesirable non-monitored acceleration forces so as to prevent its associated primary support flexure from being placed in a state of compression. In a most preferred embodiment, the overall accelerometer utilizes two spaced-apart primary support flexures and a secondary flexure associated with and located in close proximity to each primary flexure.In a preferred method of making the pendulum assembly forming part of the accelerometer of the present invention and some prior art pendulum assemblies, the pendulum arm itself (the moving member which supports the torque coil), its support member (the stationary element) and the interconnecting flexures are preferably formed as an integral unit from a wafer of fused silica. Differences in the thermal expansion of the flexure and the material making up the base of the accelerometer tends to distort the stationary support member forming part of the overall pendulum assembly and degrade the performance of the accelerometer. One approach which has been suggested in the prior art to minimize this effect is to attach the stationary element of the pendulum assembly to a metal part made from a special alloy having, as nearly as possible, the same low coefficient of expansion as the pendulum assembly itself. However, the temperature coefficients of the materials are not exactly the same, and there is still performance degradation from differential thermal expansion.Another object of the present invention is to provide an uncomplicated and yet reliable way to overcome the problems of the differential thermal expansion recited immediately above. As will be seen hereinafter, in the preferred embodiment of the present invention, this is accomplished by mounting the stationary support member forming part of the overall pendulum assembly to the main support base by means of a pair of spaced-apart flat leaf springs, each of which is connected at one end to the support member and at its opposite end to the main base with both leaf springs being disposed within planes normal to the resting plane of the pendulum and normal to the axis of movement of the pendulum. In a most preferred embodiment, as will also be seen, one of these two leaf springs bends oppositely at each end for reasons to be described and the other leaf spring is designed to have a shorter bending element than the first leaf spring, again for reasons to be discussed.Still referring to the typical pendulous type of servo accelerometer in the prior art, another problem associated with this type of accelerometer results from the fact that the previously recited torque coil is supported by its associated pendulum arm. As a result, temperature changes induce stresses into the pendulum as a result of differences in thermal expansion between the two.It is the further object of the present invention to minimize the problem just described by mounting the torque coil to the pendulum arm at discrete, spacedapart points to permit flexing of the torque coil to relieve thermal stresses. In a preferred embodiment, there are three such points which are equally spaced apart about the periphery of a section of the torque coil or torque coils.The present invention will be described in more detail hereinafter in conjunction with the drawings wherein:FIG. 1 is a diagrammatic illustration, in plan view, of a pendulous type of servo accelerometer designed in accordance with a number of different features of the present invention; andFIG. 2 is a sectional view of the accelerometer illustrated in FIG. 1, taken generally along line 2--2 in FIG. 1.Turning now to the drawing, part of an overall pendulous type of servo accelerometer designed in accordance with the present invention is generally indicated by the reference numeral 10 in FIG. 1. This accelerometer is shown including a main support base 12 constructed of, for example steel, and a housing which is generally indicated at 14 and which extends up from base 12. A pendulum assembly 16, designed in accordance with the present invention as will be seen hereinafter, is supported within housing 14 above main support base 12 by a pair of spaced-apart support members 18A and 18B connected directly to and extending up from base 12. These support members are typically constructed of the same material as base 12 and, in fact, may be formed as an integral unit with the base. As will be seen hereinafter, overall accelerometer 10 also includes a servo arrangement which cooperates with pendulum assembly 16 for monitoring the presence and magnitude of certain acceleration forces, if present, applied to the accelerometer in a particular direction.Pendulum assembly 16 may be divided into three parts, (1) a flat, thin pendulum 20, (2) a flat, thin pendulum support 22 and (3) four flexures 24A, 24B, 24C and 24D, which interconnect the pendulum and pendulum support in the manner to be described below. In an actual working embodiment, these three parts are integrally formed from a thin wafer of fused silica. The flexures 24 are made thinner than the pendulum and pendulum support by means of chemical etching or other suitable means so that they support the pendulum for limited rotational movement relative to the pendulum support in the manner to be explained immediately below.Pendulum 20 is itself comprised of a forwardmost arm and torque coil end 26 and a support end 28 which is comprised of four distinct legs 28A, 28B, 28C and 28D. The pendulum support 22 includes an arrangement of legs 22B and 22D adjacent to legs 28B and 28D and sections 22A and 22C adjacent to legs 28A and 28C.As can be seen from FIGS. 1 and 2, the entire pendulum assembly 16, that is, pendulum 20, pendulum support 22, and the four flexures 24, lie within a common resting plane. The four flexures are located across a common fixed axis generally indicated by dotted lines at 30 in FIG. 1 and hold pendulum arm 20 to pendulum support 22 while also permitting limited rotational movement of the pendulum through its normal resting plane about axis 30. As will be seen below, the pendulum support is fixedly maintained in its resting plane above base 12 by leaf springs 32 and 34 which connect the pendulum support directly to support members 18A and 18B as discussed in detail hereinafter.As indicated above, overall accelerometer 10 includes a servo arrangement which cooperates with pendulum assembly 16 to monitor the presence and magnitude of certain acceleration forces applied to the accelerometer. The specific acceleration forces to be monitored are those that act on end section 26 of the pendulum normal to its resting plane. The servo arrangement includes side-by-side torque coils 36 (see FIG. 2) wound within associated support bobbins 38 mounted to the end section 26 of pendulum 20 in a manner to be described hereinafter. The torque coils are immersed within a magnetic field provided by magnets 40 having pole pieces 42 supported within magnet housings 44, as best illustrated in FIG. 2. As is also best seen in this Figure, metal targets 46 are carried by and on opposite sides of pendulum section 26 while position-sensing coils 48 are disposed in confronting relationship with the metal targets, as shown. These sensors which are supported by suitable means 50, the metal targets, the means defining the magnetic field itself, and the torque coils along with an electronic circuitry including flexible current lead wires 51 form the servo arrangement.It is to be understood that, with certain exceptions to be noted, accelerometer 10 as described thus far including the pendulum assembly and servo arrangement is well-known in the art and thus has not been described in detail. As discussed above, the pendulum is supported for limited rotational movement through its resting plane in response to acceleration. When the pendulum is subjected to acceleration forces normal to this plane, it tries to move from its resting plane. At the same time, the torque coils are energized with a sufficient amount of current from a suitable source through leads 51 which in combination with the magnetic field, the metal targets 46 and sensors 48 maintains the pendulum in its resting plane precisely positioned between the two sensors. The amount of current required to accomplish this is proportionate to the acceleration forces applied to the pendulum and therefore by monitoring these currents the acceleration forces can be monitored. This technique by itself is not new and, hence, will not be described in further detail. It is only important to emphasize here that the acceleration forces being monitored are those forces or force components applied to pendulum 20 in a direction normal to its resting plane.As indicated above, with certain exceptions, overall pendulum accelerometer 10 is well-known in the art. One exception resides in the particular arrangement of flexures 24. Heretofore, a typical pendulum corresponding to pendulum 20 has been supported to its pendulum support corresponding to support 22 by means of two flexures only, specifically flexures 24A and 24C. As a result, the overall accelerometer could be subjected to acceleration forces that would place these flexures in a state of compression as described above, thereby causing the flexures to crumble, break or otherwise fail. In accordance with one feature of the present invention, the additional flexures 24B and 24D are arranged in the manner illustrated in FIG. 1 so as to be placed in a state of tension by acceleration forces that would otherwise place the flexures 24A and 24C in a state of compression. In that way, the flexures 24B and 24D prevent the flexures 24A and 24C from actually being placed in compression.A second difference between accelerometer 10 and those known in the art resides in the particular way in which pendulum support 22 is maintained in its stationary position. As indicated above, the pendulum support is connected to members 18 by means of leaf springs 32 and 34. As indicated above, certain pendulum assembly parts which include the support, the flexures, and the pendulum arm, are preferably manufactured as a single unit from a wafer of fused silica. This material is to be contrasted with the material making up base 12, which has a different coefficient of thermal expansion. Differences in the thermal expansion of the flexure material and the base material tend to distort the stationary part of the pendulum assembly, specifically pendulum support 22 and degrade the performance of the accelerometer. As indicated above, one method suggested heretofore to minimize this effect was to attach the stationary part of the pendulum assembly to a metal part made of a special alloy having, as nearly as possible, the same low coefficient of expansion as the flexures. However, the temperature coefficients of the materials are not exactly the same and there is still performance degradation from differential thermal expansion. In accordance with another aspect of the present invention, leaf springs 32 and 34 are used to support the stationary part of the pendulum assembly, that is, pendulum support 22, to support members 18 in a manner to be described immediately below.As illustrated best in FIG. 1, the two flat leaf springs 32 and 34 extend within planes normal to the resting plane of pendulum assembly 16 and also normal to axis 30. This permits expansion of the pendulum assembly (e.g., the fused silica) relative to the accelerometer base 12 and supports 18A and 18B. Moreover, one of these springs, specifically spring 34 bends oppositely at each end to permit linear movement perpendicular to the plane of the leaf spring.Relative thermal expansion of the pendulum material and the material of the base causes one end of flexure 34 to move relative to the other end, in a direction perpendicular to the original plane of the flexure. The end sections of this flexure are constrained from rotation by their attachment to other members, so the end sections are then in parallel, but displaced, planes. Near one end, the center section of the flexure bends toward the plane of the other end; near this other end the center section bends back to join that end in its plane which is parallel to, but displaced from, the plane of the first end, so the center section bends oppositely near its opposite ends. The other leaf spring, specifically leaf spring 32, has a shorter bending element to accommodate slight alignment changes and also provides sufficient stiffness to linear motion parallel to the hinge axis to prevent low frequency vibration of the mass supported by these leaf springs.Still another difference between accelerometer 10 and those known in the prior art resides in the way in which torque coils 36 and their respective bobbins 38 are mounted to pendulum 20. Specifically, the torque coil and bobbins are connected to the pendulum at three points only which points are equally circumferentially spaced about the annular section 26. These points are generally indicated at points P.sub.1, P.sub.2 and P.sub.3 in FIG. 1. The bobbins are mounted to the pendulum by suitable and readily providable bonding means. The P.sub.1 point of connection is illustrated in FIG. 2. Note from this latter figure that the bottom end of each bobbin (its six o'clock position in FIG. 1) is not connected to the pendulum. Connecting the torque coils and their bobbins to the pendulum in this manner permits flexing of the torque coil to accommodate thermal expansion differences between the torque and the fused silica pendulum part.

公开(公告)号：US06484578B2

公开(公告)日：2002-11-26

申请号：US09398719

申请日：1999-09-20

Applicant: James R. Woodruff ,  Steven A. Foote

Inventor： James R. Woodruff ,  Steven A. Foote

IPC: G01P1508

CPC classification number: B81B3/0081 ,  B81B2201/0235 ,  B81C2201/014 ,  B81C2201/019 ,  G01P1/023 ,  G01P15/0802 ,  G01P15/097 ,  G01P2015/0814 ,  G01P2015/0828

Abstract: A pendulous accelerometer wherein the active reaction mass is pendulously mounted external to a fixed support structure and may include sensor cover of covers in the total active reaction mass.

Abstract translation: 一种下摆加速度计，其中所述活性反应物质被下摆地安装在固定的支撑结构外部，并且可以包括在所述总活性反应物质中的盖的传感器盖。

公开(公告)号：US5450762A

公开(公告)日：1995-09-19

申请号：US320565

申请日：1994-10-11

Applicant: James R. Woodruff ,  David W. Wine

Inventor： James R. Woodruff ,  David W. Wine

IPC: G01L1/10 ,  G01L1/16 ,  G01L1/18 ,  G01L1/00

CPC classification number: G01L1/162 ,  G01L1/106 ,  G01L1/183 ,  Y10S73/01

Abstract: A reactionless single beam vibrating force transducer utilizes counterbalances at opposite ends of the beam that rotate in directions opposite to the ends of the vibrating beam to reduce rotational and normal forces transmitted to the end supports for the beam. The proportions of the counterbalances relative to the size of the beam may be chosen to reduce forces in a direction normal to the beam to zero at the expense of some rotational moments at the end of the beam support, or to reduce moments at the expense of some normal force. The relative amounts of residual rotational moments and normal force can be adjusted to suit particular applications. Flexures may also be utilized to reduce the rotational moments transferred to the beam support even further.

Abstract translation: 无反应的单梁振动力传感器在梁的相对端处利用平衡，其在与振动梁的端部相反的方向上旋转，以减少传递到梁的端部支撑件的旋转和法向力。 可以选择平衡相对于梁的尺寸的比例，以将梁的垂直方向的力减小到零，这是以波束支撑端部的某些旋转力矩为代价的，或以牺牲 一些正常的力量。 可以调整残余转动力矩和法向力的相对量，以适应​​特定应用。 还可以使用弯曲来进一步减少传递到梁支撑件的旋转力矩。

公开(公告)号：US5339698A

公开(公告)日：1994-08-23

申请号：US72903

申请日：1993-06-07

Applicant: Michael J. Robinson ,  James R. Woodruff

Inventor： Michael J. Robinson ,  James R. Woodruff

IPC: G01L1/16 ,  G01L1/00

CPC classification number: G01L1/162

Abstract: A vibrating beam force transducer is comprised of an oscillating sensing element having a frequency output indicative of the force applied to the sensing element. The sensing element has a variable electrical resistance which can vary in accordance with temperature fluctuations over the operating range of the transducer.A drive circuit is electrically coupled to the sensing element for causing the sensing element to oscillate at a resonant frequency that is a function of the force applied to the sensing element. The drive circuit includes a source of DC voltage, which is utilized for altering the electrical characteristics of the drive circuit in response to variations in the electrical resistance of the sensing element.

Abstract translation: 振动梁力传感器包括具有指示施加到感测元件的力的频率输出的振荡感测元件。 感测元件具有可变电阻，其可以根据换能器的操作范围上的温度波动而变化。 驱动电路电耦合到感测元件，用于使感测元件以作为施加到感测元件的力的函数的谐振频率振荡。 驱动电路包括直流电压源，其用于响应于感测元件的电阻的变化而改变驱动电路的电特性。

公开(公告)号：US06745627B1

公开(公告)日：2004-06-08

申请号：US08651927

申请日：1996-05-21

Applicant: James R. Woodruff ,  Peter J. Hesketh

Inventor： James R. Woodruff ,  Peter J. Hesketh

IPC: G01P1510

CPC classification number: G01P15/0802 ,  G01P15/097 ,  G01P2015/0814 ,  G01P2015/0828

Abstract: A vibratory transducer (22) for an accelerometer (2) having a pair of parallel beams (50, 52) with first and second fixed end portions, and a pair of electrodes (62, 64) positioned adjacent to the beams for generating an electrostatic force to transversely vibrate the beams at a resonant frequency. The vibration frequency of the beam is generally related to axial (i.e., compression or tension) forces applied to either one of the fixed ends of the beam so that the magnitude of the force applied can be measured by changes in the vibration frequency. The electrodes and the beams each have a plurality of fingers (82, 80) extending laterally outward so that the beam fingers and the electrode fingers are intermeshed with each other. The intermeshed fingers reduce the transducer's sensitivity to changes in applied voltage, thereby increasing the accuracy of the frequency signal. In addition, the intermeshed fingers enable the transducer to operate effectively at pressure levels substantially above vacuum to permit gas damping of the proof mass.

Abstract translation: 一种用于加速度计（2）的振动换能器（22），其具有一对具有第一和第二固定端部的平行梁（50,52），以及一对邻近所述梁定位的电极（62,64），用于产生静电 力以共振频率横向振动光束。 梁的振动频率通常与施加到梁的任一个固定端的轴向（即压缩或张力）相关，使得施加的力的大小可以通过振动频率的变化来测量。 电极和光束各自具有横向向外延伸的多个指状物（82,80），使得光束指状物和电极指彼此相互啮合。 相互啮合的手指降低了传感器对施加电压变化的敏感度，从而提高了频率信号的精度。 此外，相互啮合的手指使传感器能够在基本上高于真空的压力水平下有效地运行，以允许气体阻尼检测质量块。

公开(公告)号：US06248610B1

公开(公告)日：2001-06-19

申请号：US09307257

申请日：1999-05-06

Applicant: Ronald B. Leonardson ,  James R. Woodruff

Inventor： Ronald B. Leonardson ,  James R. Woodruff

IPC: H01L2100

CPC classification number: G01P15/097 ,  G01P15/0802 ,  G01P2015/0828

Abstract: An accelerometer formed from a semiconducting substrate and first and second active layers coupled to the opposite surfaces of the substrate. The substrate has a frame and a proof mass suspended from the frame by one or more flexures for rotation about an input axis in response to an applied force. The active layers each include a vibratory force transducer mechanically coupled to the proof mass for detecting a force applied to the proof mass. With this configuration, the transducers are located on either side of the substrate, which improves the differential design symmetry of the force detecting apparatus. This reduces the common mode non-linear response characteristics of the accelerometer, particularly in high dynamics applications, where high performance is required.

Abstract translation: 由半导体衬底形成的加速度计和耦合到衬底的相对表面的第一和第二有源层。 衬底具有一个框架和一个证明质量块，通过一个或多个挠曲件从框架悬挂，以响应于所施加的力围绕输入轴线旋转。 有源层各自包括机械耦合到检测质量块的振动力传感器，用于检测施加到检验质量块的力。 通过这种构造，换能器位于基板的两侧，这改善了力检测装置的差分设计对称性。 这降低了加速度计的共模非线性响应特性，特别是在需要高性能的高动态应用中。