Patent Description:
Automatic control systems are widely used in construction machines. The use of automatic control systems in construction machines improves the accuracy of work performed using construction machines, cuts fuel and construction material consumption, brings down skill requirements for operating construction machines, and reduces fatigue of construction machine operators. For example, automatic control systems are used to control grader and bulldozer blades, asphalt and concrete pavers, and excavator buckets. Such automatic control systems are typically used to hold the operative organ of the machine at a desired height to track a design project. To estimate the current height of the operative organ, different sensors are employed, such as Global Navigation Satellite System (GNSS) sensors, laser sensors, ultrasonic sensors, etc. The drawbacks of such sensors include infrequent update rate, delay in response time, and poor short-term stability. To solve these issues, the sensors are often integrated with inertial sensors, such as angular rate sensors (gyroscopes) and/or accelerometers, installed on the machine.

Unfortunately, construction machines are subject of shock and vibration impacts with high level amplitudes that are caused by the working movements of the construction machines, and such impacts negatively affect the inertial sensors. This problem is particularly prevalent for bulldozers and excavators. The impacts are often caused by stones either hitting a blade or bucket or falling into a vehicle's base mounting (for example, between a track and rollers). Similar impacts can also be caused by a hydraulic rod, if there is an air gap at the pivot point to the blade. Rollers themselves moving on tracks (especially at the point of track shoes connection) also create vibration impact. The influence of such impacts, especially in the <NUM> or higher frequency range, negatively affects the proof mass stability, which is a measuring element of inertial sensors of micromechanical types (e.g., MEMS - micro electro mechanical system). This is the micromechanical sensor (MEMS sensor) that is the most widely utilized due to its high accuracy, reliability, compactness, and low cost.

Shock and vibration impacts on the construction machine can result in errors in a sensor's output signal. Fortunately, sensors have a selectivity to impact frequencies. There are frequencies to which the proof mass is sensitive and frequencies to which the proof mass is insensitive. Both accelerometers and gyroscopes are built on the basis of a mechanical oscillating/vibrational circuit with some internal frequencies. If in the spectrum, there are harmonics equal to the resonance frequency, an error is generated. It is desirable that such frequencies need to be mechanically filtered. Accordingly, a shock absorption system that prevents impacts of such frequencies from being transferred to the sensor is desirable. <CIT> discloses systems and methods for isolated sensor device protection. In one embodiment, an isolated sensor device comprises: a housing having an isolation chamber; an isolator sealed within the isolation chamber; an inertial sensor assembly sealed within the isolation chamber, the inertial sensor assembly coupled to an inner surface of the isolation chamber by the isolator; and at least one progressive impact interface applied to a periphery of the inertial sensor assembly, wherein the at least one progressive impact interface extends outward from the inertial sensor assembly towards the inner surface. <CIT> discloses an elastomeric vibration and shock isolation for inertial sensor assemblies. An inertial sensor system has a base, an inertial sensor, and an isolator mount. The isolator mount fastens the inertial sensor to the base, and the isolator mount includes a bolt and first and second vibration absorbing members. The bolt is inserted through the inertial sensor and the base, the first vibration absorbing member is between the bolt and the inertial sensor, and the second vibration absorbing member is between the inertial sensor and the base. The isolator mount isolates the inertial sensor from vibration, shock, and/or acoustic noise transmitted from a host system through the base.

In accordance with various embodiments, a three-axis inertial sensor damper suspension apparatus is provided that acts as a mechanical filter and prevents shock and vibration impacts on a construction machine from being transferred to one or more inertial sensors used by an automatic control system of the construction machine.

In accordance with one embodiment, an inertial sensor suspension apparatus that is mountable on a construction machine for preventing impacts on the construction machine from being transferred to one or more inertial sensors comprises a pocket, a lid, a core disposed in the pocket and covered by the lid, one or more inertial sensors attached to the core, a plurality of elastomer insertions attached to the core and forming an upper wedge between the core and the lid and a lower wedge between the core and the pocket, and a coupler that provides controlled connection of the pocket and the lid to compress the plurality of elastomer insertions using a force corresponding to a target resonance frequency for the inertial sensor suspension apparatus.

In accordance with another embodiment, a system comprises a construction machine having an operative organ, one or more inertial sensors configured to measure at least one of acceleration or angular rate of the operative organ of the construction machine, and an inertial sensor suspension apparatus for preventing impacts on the construction machine from being transferred to the one or more inertial sensors, the inertial sensor suspension apparatus. The inertial sensor apparatus comprises a pocket, a lid, a core disposed in the pocket and covered by the lid, wherein the one or more inertial sensors are attached to the core, a plurality of elastomer insertions attached to the core and forming an upper wedge between the core and the lid and a lower wedge between the core and the pocket, and a coupler that provides controlled connection of the pocket and the lid to compress the plurality of elastomer insertions using a force corresponding to a target resonance frequency for the inertial sensor suspension apparatus.

These and other advantages of the embodiments will be apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings.

According to an embodiment of the present invention, the three-axis inertial sensor damper suspension system utilizes the principle of a passive mechanical oscillating system, and includes a heavy metal core with inertial sensors fixed to its face. The core can be cubic shaped. All the eight cube corners are pyramidal-truncated, with the elastomer layer being placed onto them. Latex rubber or silicon rubber with a low factor of residual deformation (compression set) can be used as the elastomer. The elastomer serves as a spring to produce oscillations and a damper to further attenuate those oscillations (two-in-one). The elastomer is initially pressed/strained with a certain force to provide a desired resonance frequency of the suspension. The resonance frequency is determined from an amplitude-frequency response (AFR) used for describing characteristics of an oscillating system and efficiency of a suspension system in suppressing shock and vibration impacts. The parameter components of the suspension can be calculated and then specified in testing on a vibration work bench. This allows the AFR to be estimated, such that the AFR meets the requirements on resonance frequency, and proves the suppression efficiency of the suspension system.

In an advantageous embodiment, the core is inserted vertically down into a pocket (gap), in which bottom angles are formed as counterparts to the four truncated corners of the bottom of the core. The cubic core and the pocket are closed by a lid, and on the bottom side of the lid there are also angles formed as counterparts to the four truncated corners on the top of the core. The lid can be screwed by a central coupling screw at a target moment controlled by a torque screwdriver. The lid and coupling screw can then be locked by side screws (counter screws). It is to be understood that directions up, down, vertical are conditional and relative to the core and the three-axis suspension system and are used herein for descriptive purposes. The three-axis suspension system can be used at arbitrary orientations in a construction machine and efficiently works at any direction of shock impact and vibration effects.

According to an advantageous aspect of the present invention, the top and bottom truncated corners of the core, as well as their counterparts in the pocket and lid serve as a wedge system. The vertical force of the central coupling screw is transferred into a hold-down/clamping pressure on the elastomer corners. The resonance frequency is proportional to the pressure, the pressure is proportional to the screw force, and finally the screw force is proportional to the torque moment. The torque moment thus defines suspension's resonance frequency. Accordingly, torque moment can be controlled to achieve a target resonance frequency of the suspension system in control the AFR of the suspension system to mechanically filter shock and vibration impacts so as not to transfer the impacts to the inertial sensors.

<FIG> illustrates a cubic-shaped core having elastomer inserts installed on the core's corners according to an embodiment of the present invention. As illustrated in <FIG>, a three-axis inertial sensor damper suspension apparatus includes a core <NUM> and eight insertions <NUM>. The core <NUM> can be shaped as a cube with pyramidal-truncated corners, as shown in <FIG>. The insertions <NUM> are respectively installed onto the truncated cube corners of the core <NUM>. It is to be understood that although only one of the insertions <NUM> is numbers as "<NUM>" in <FIG> for sake of clarity, the description of the insertions <NUM> herein applies similarly to the insertions installed at all of the corners of the core <NUM>. The same approach is used for other elements in the figures as well.

The core <NUM> is advantageously made from a high density material that provides a heavy weight relative to the size of the core <NUM>. For example, the core can be made from stainless steel, brass, or bronze, but the present invention is not limited thereto. The insertions <NUM> are made of an elastomer with a low stiffness ratio, low property change within an industrial temperature range (e.g., -<NUM>. +<NUM>), and low residual deformation i.e. low material shape changes after removing force impact. In an advantageous embodiment, the elastomer used for the insertions <NUM> is natural rubber (latex) or a type of silicon rubber. Aligning pins <NUM> are formed on the underside of each insertion <NUM>. Aligning pins <NUM> on the underside of each insertion <NUM> are inserted into corresponding holes <NUM> in the truncated corners of the core <NUM> and held in place in the corresponding holes <NUM> by friction during assembly. On each of the six faces of the core <NUM>, recesses <NUM> and holes <NUM> are formed to fasten printed circuit boards (PCBs) with inertial sensors. The core <NUM> also includes a tubular central opening <NUM> that passes through the top and bottom faces of the core <NUM>. The central opening <NUM> passes through the top and bottom faces of the core and forms a hollow channel through the center of the core <NUM>.

<FIG> illustrates installation of PCB with inertial sensors onto faces of the core <NUM>. As illustrated in <FIG>, boards <NUM> with inertial sensors are installed on a number of the faces of the core <NUM>. The holes <NUM> in the faces of the core <NUM> can be threaded screw holes, and the boards <NUM> can be installed on the faces of the core <NUM> with recesses <NUM> by tightening screws <NUM> through holes in the boards <NUM> and into the screw holes <NUM> in the faces of the core <NUM>. The boards <NUM> are printed circuit boards (PCBs) with inertial sensors. Each board <NUM> has a connector <NUM> to output electrical signals from the inertial sensors and to input and provide power to the board <NUM>. The connector <NUM> on each board <NUM> can connect to a computer system of a construction machine. The computer system of the construction machine provides power to the boards <NUM> via the connectors <NUM> and receives electrical signals providing measurements of the inertial sensors output by the connectors <NUM>. Both digital and/or analog inertial sensors can be used on board <NUM>. Analog sensors typically output analog voltage or current via connector <NUM>. This signal is then digitized by means of an analog to digital converter (ADC). Digital sensors have an ADC inside the chip and output a digital pulse signal on connector <NUM> according some standard digital interface, e.g., serial peripheral interface (SPI), I2C, etc. A digit from the ADC represents an actual physic value (acceleration, angular rate) and is further processed in central processor unit (CPU) of computer system according a target math processing algorithm. Depending on the type and number of the inertial sensors, there can be one, two, three, or more boards <NUM> installed on respective faces of the core <NUM>. In an advantageous embodiment shown in <FIG>, three identical boards <NUM> are installed on respective faces of the core, with a single axial inertial sensor installed on each board <NUM>. Together, the three boards <NUM> provide three-axis measurements (XYZ) generating a full-scale vector of angular rate or acceleration. The use of such a vector is a standard approach in integrating inertial sensors with different sensors. For example, a typical target math algorithm to couple inertial and GNSS positioning data can be based on a Kalman Filter (KF) approach. The three boards <NUM> need to be installed on orthogonal planes (i.e., the angle between the planes is <NUM>°). Accordingly, as shown in <FIG>, the three boards <NUM> are installed on three orthogonal faces of the core <NUM>. The use of three boards <NUM> with uniaxial inertial sensors installed on three orthogonal faces of the core <NUM> provides a three-axis, centrally-symmetrical suspension system that is efficient in all of the three axes.

In other possible embodiments, two-axial inertial sensors, or a three-axial inertial sensor can be used. In such embodiments, the number of boards <NUM> can be correspondingly reduces. For example, in a case in which two-axis inertial sensors are used, two boards <NUM> can be installed on respective faces of the core <NUM>. In a case in which, a three-axis inertial sensor is used, one board <NUM> can be installed on a face of the core <NUM>.

<FIG> illustrates a pocket <NUM> in which the core <NUM> is placed according to an embodiment of the present invention. As shown in <FIG>, bottom internal corners of the pocket <NUM> are formed with counterparts <NUM> to the insertions <NUM> installed on the truncated corners of the core <NUM>. The counterparts <NUM> formed in the bottom internal corners of the pocket <NUM> are pyramidal shaped and correspond to the shape of the insertions <NUM> installed on the pyramidal-truncated corners of the core <NUM>, such that a flat triangular surface of a corresponding insertion <NUM> rests on a triangular surface of each counterpart <NUM>. As shown in <FIG>, there are four counterparts <NUM> corresponding to the insertions <NUM> on the four bottom corners of the cubic-shaped core <NUM>. A threaded boss <NUM> is installed at the center of the bottom internal surface of the pocket <NUM>. The threaded boss <NUM> provides a threaded hole in which a screw can be tightened. The sides of the pocket <NUM> that correspond to faces of the core <NUM> on which boards <NUM> with inertial sensors are installed are formed with windows <NUM> and <NUM> that allow wires to run to/from the connectors <NUM> of the boards <NUM>. The windows <NUM> and <NUM> are cutouts in the sides of the pocket <NUM> that accommodate the connectors <NUM> of the boards <NUM> so wires can be connected to the connectors <NUM> when the core <NUM> is installed within the pocket <NUM>. Each side of the pocket is formed with threaded holes <NUM>. In the embodiment of <FIG>, two threaded holes <NUM> are provided on each side of the pocket <NUM> for a total of eight threaded holes <NUM>. The general requirement for the pocket <NUM> is mechanical strength, and there are no specific requirements to its weight (compared to the core <NUM>). In an exemplary embodiment, the pocket <NUM> can be produced using an aluminum alloy by a die casting method.

<FIG> illustrates assembly of the three-axis inertial sensor damper suspension apparatus according to an embodiment of the present invention. As shown in <FIG>, the core <NUM> with the installed insertions <NUM> and boards <NUM> is placed into the pocket <NUM> and covered by a lid <NUM>. The lid <NUM>, like the pocket <NUM>, can be made of an aluminum alloy. A bottom flange formed by the insertions <NUM> on the four bottom corners of the core <NUM> lies on the corresponding counterparts <NUM> formed in the bottom internal corners of the pocket <NUM>. The lid <NUM> is formed with four counterparts in the internal corners of the bottom side of the lid. The counterparts of the lid are similar to the counterparts <NUM> in the pocket <NUM>. The four counterparts of the lid <NUM> correspond to the insertions <NUM> installed on the four upper corners of the core <NUM>. The counterparts of the lid <NUM> cover an upper flange formed by the insertions <NUM> on the four upper corners of the core <NUM>. The lid <NUM> is formed with a central opening <NUM> that aligns with the central opening <NUM> of the core <NUM> when the lid <NUM> covers the core <NUM>. The threaded boss <NUM> of the pocket also aligns with the central opening <NUM> of the core <NUM> when the core <NUM> is placed in the pocket <NUM>. A coupling screw <NUM> passes through the central opening <NUM> of the lid <NUM> and the central opening <NUM> of the core <NUM> and is screwed into the threaded boss <NUM>. The moment (MZ) <NUM> of tightening coupling screw <NUM> is controlled by a torque screwdriver. In particular, the moment <NUM> of coupling screw <NUM> is controlled to be equal to a specific value defining a target spring factor K of the suspension. Once coupling screw <NUM> is tightened and controlled to have a specific desire moment <NUM>, screws <NUM> are tightened to lock coupling screw <NUM> to prevent spontaneous twisting (screwing or unscrewing) of screw <NUM>. This locks coupling screw <NUM> at the desired moment <NUM>, which keeps the spring factor of the suspension at the target spring factor K. As shown in <FIG>, screws <NUM> are tightened through threaded holes in the lid formed perpendicular to the central opening <NUM> to lock coupling screw <NUM>. Then, screws <NUM> are tightened through threaded holes <NUM> of the pocket <NUM> to lock the lid <NUM> into the pocket and prevent spontaneous movements of the lid <NUM>. For example, eight screws <NUM> are used to lock the lid <NUM> in the embodiment of <FIG>. Spontaneous movements of the lid can be caused by random impacts resulting in generating large moments of impulse due to the considerable weight of the core <NUM>. This may result in the lid <NUM> being displaced and a single coupling screw <NUM> will not typically be enough to prevent displacements of the lid <NUM>.

<FIG> illustrates an assembled a three-axis inertial sensor damper suspension apparatus <NUM> according to an embodiment of the present invention. In the assembled suspension apparatus <NUM>, the core <NUM> is placed within the pocket <NUM> and covered by the lid <NUM>. Coupling screw <NUM> passes through the central opening <NUM> of the lid <NUM> and the central opening <NUM> of the core <NUM> and tightened into the threaded boss <NUM> of the pocket <NUM> to a specific desired moment <NUM>. Coupling screw <NUM> is locked into place by screws <NUM>, and the lid <NUM> is locked into place in the pocket <NUM> by screws <NUM>.

<FIG> shows a top view of the suspension apparatus <NUM> cut by a plane B-B <NUM>. <FIG> shows an internal section of the suspension apparatus <NUM> along the plane B-B <NUM>. As shown in <FIG>, top and bottom flanges formed by the insertions <NUM> form corresponding top and bottom pyramid wedges <NUM> and <NUM>. Wedges <NUM> and <NUM> transform the force of coupling screw <NUM> into a pressure that compresses the elastomer insertions <NUM>. In particular, the vertical force of the coupling screw <NUM> is transferred into a clamping pressure on the top and bottom wedges <NUM> and <NUM> that compresses the elastomer insertions <NUM>. When coupling screw <NUM> is tightened, the counterparts of the lid <NUM> compress the top wedge <NUM> formed by the upper elastomer insertions <NUM> and the bottom wedge and the bottom wedge <NUM> formed by the lower elastomer insertions <NUM> are compressed against the counterparts <NUM> of the pocket <NUM>. The resonance frequency of the suspension is proportional to the pressure compressing the elastomer insertions <NUM>, the pressure is proportional to the force of the coupling screw <NUM>, and the force of the coupling screw <NUM> is proportional to the torque moment <NUM> which is controlled to be a desired value when the coupling screw <NUM> is tightened. Accordingly, the torque moment <NUM> of coupling screw <NUM> defines the suspension's resonance frequency. In this way, all gaps related to tolerances, manufacturing non-idealities of components of the suspension apparatus <NUM> are taken up, the necessary spring factor is provided, and hence, the target amplitude-frequency response (AFR) needed to suppress vibration and shock impacts is achieved.

It can be noted that manufacturing tolerances for elastomer parts are considerably greater than that of metal parts. This is due to the physical nature of the elastomer, technology related to manufacturing the elastomer, and curing and shrinkage of the elastomer. However, the arrangement of the elastomer insertions <NUM> to form the wedges <NUM> and <NUM>, according to an advantageous embodiment of the present invention, solves the problems that may arise due to the manufacturing tolerances of the elastomer parts.

<FIG> illustrates an example of an amplitude-frequency response (AFR) the suspension apparatus <NUM> according to an embodiment of the present invention. As shown in <FIG>, the AFR of the suspension apparatus <NUM> should have a gain factor of one for low frequencies where the useful signal is present. The useful signal refers to the object acceleration and/or angular rate measured by the inertial sensors. Due to the gain equal to one for low frequencies, there is no deterioration or amplification of the useful signal and the accuracy of the measurements of the inertial sensors is preserved. At higher frequencies, there is a resonance peak <NUM> and then attenuation of the gain factor almost to zero, which eliminates any effects of shock and vibration impacts on the measurements by the inertial sensors. The frequency at which the resonance peak <NUM> is reached is the resonance frequency. The closer the AFR is to zero in frequencies above the resonance frequency, the better.

The resonance frequency is a parameter of the AFR, and should be fixed. To maximize attenuation in the field of high frequencies (above the resonance frequency), the resonance frequency should be as small as possible, but the resonance peak <NUM> should not be in the low frequency area in which the desired signal is present, so as not to deteriorate or amplify the desired signal. In addition, the resonance frequency is to be high enough to prevent natural vibrations produced by the construction machine's engine, transmission, and chassis from being in the resonance peak <NUM> area, and also to prevent suction of external energy and hence permanent oscillation of the core <NUM>. For most construction machines the frequency spectrum of natural vibration has a range of <NUM>. <NUM> so a resonance frequency within the range of <NUM>-<NUM> meets such requirements. In this case, the suspension apparatus <NUM> will transfer dangerous impact energy from the area of frequencies of <NUM> to a safe range of <NUM>-<NUM> and dissipate this energy there. In order to transfer dangerous high-frequency impact energy to the safe range, the wedges <NUM> and <NUM> formed by the elastomer insertions <NUM> act as a spring to produce oscillations in the safe range due to the impact energy and act as a damper to attenuate those oscillations. Behavior of oscillations in the safe range is defined by the Q-factor. In this case, the Q-factor is the amplitude of the AFR at the resonance peak <NUM>. The greater the value of the Q-factor, the better the dissipation of energy in the safe range and stronger the attenuation in the area of <NUM>. The Q-factor should be as large as possible. For example, in exemplary embodiments of the present invention, the Q-factor is <NUM> or greater and mostly defined by elastomer physical properties. Both already mentioned latex and silicone rubbers are examples of materials which provide good Q factor.

At the output of each inertial sensor there is an analog electric narrowband low pass filter with typical bandwidth of <NUM>. The filter rejects electrical noise and provides a narrowband spectrum for further digitization (discretization and quantization) in ADC. The same filter prevents a resonance peak <NUM> from affecting sensor measurements. Accordingly, when the suspension apparatus <NUM> dampens vibrations to transfer high-frequency impact energies to the resonance frequency (or a safe resonance frequency range), the electric filter prevents the oscillations of the suspension apparatus from affecting the sensor measurements. It is important to control the position of the resonance peak <NUM> relative to the frequencies of the construction machine's vibrations, as described above. That is, the position of the resonance peak <NUM> should be set so as to prevent vibrations produced by the construction machine's engine, transmission, and chassis from being in the resonance peak <NUM> area. The electrical filter protects the desired signal from the inertial sensors from short-term effects, but is inefficient when powerful periodic vibrations are prevalent. So in exemplary embodiment, a resonance frequency within the range of <NUM>-<NUM> may be used to avoid amplification of natural vibration by resonance peak area and passing them to sensor output.

The following equation shows a dependence of the resonance frequency f<NUM> of peak <NUM> on the mass M of the core <NUM> and the total spring factor K of the suspension apparatus <NUM>: <MAT> Accordingly, given the mass M of the core <NUM> and the target resonance frequency f<NUM> for the AFR of the suspension apparatus <NUM>, a target total spring factor K of the suspension apparatus <NUM> is calculated using the above expression. A value of the torque moment <NUM> of coupling screw <NUM> is determined that will result in the calculated target total spring factor K, and the tightening of coupling screw <NUM> is controlled by a torque screw driver to apply the torque moment <NUM> of the determined value. The dependency of the spring factor K from the torque moment <NUM> cannot be shown with a simple analytic equation because of the difficulty in modeling elastomer properties. Accordingly, the torque moment <NUM> necessary to achieve desired resonance frequency f<NUM> can be chosen experimentally by testing the suspension system on a laboratory vibration table. The torque is incrementally changed and each swing time AFR, such as the AFR shown <FIG>, is measured and its peak frequency is compared with desired value. The greater the mass M in the denominator of the above equation, the less the total spring factor variation ΔK will affect variation Δf of the resonance frequency f<NUM>, since ΔK is divided by M: <MAT> Moreover, the requirements to sustaining the accuracy of the total spring factor K of the suspension apparatus <NUM> and adjustment accuracy (mostly adjustment of moment MZ <NUM>) of the suspension apparatus <NUM> at the manufacturing floor are also reduced. Maximal mass M of the core <NUM> reduces the requirements to absolute value of the spring factor of the elastomer insertions <NUM> which typically cannot be very low due to the technological process of elastomer manufacture as well. This is because frequency f<NUM> is proportional to ratio between K and M. The more M the more K will be acceptable for the same f<NUM>. In order to achieve maximal mass M of the core <NUM>, the core may be made from a high density material, such as stainless steel, brass, or bronze, as described above. Due to the advantageous of maximal mass M of the core <NUM>, the dimensions of the core <NUM> can be defined by permissible internal sizes of the whole apparatus <NUM>.

<FIG> illustrates an example of external view of an inertial measurement unit (IMU) housing with the suspension apparatus <NUM> inside. As shown in <FIG>, the IMU has a housing <NUM>, usually made from die casted aluminum alloy, and electrical connector <NUM> that provides a cable connection to read inertial data measured by the inertial sensors.

The IMU <NUM> is mounted on a construction machine, such as a bulldozer, grader, asphalt or concrete paver, excavator, etc. The inertial sensors measure acceleration and/or angular rate of an operative organ (e.g., blade, bucket, etc.) of the construction machine. The inertial sensors can be used in coupling with other sensors, such as GNSS, laser sensors, supersonic sensors, etc., to track a height or position of the operative organ of the construction machine. The measurements of the inertial sensors can be sent as electrical signals to an automated control system of the construction machine. The suspension apparatus <NUM> prevents shock and vibration impacts on the construction machine from being transferred to the inertial sensors.

Claim 1:
An inertial sensor suspension apparatus (<NUM>) mountable on a construction machine (<NUM>) for preventing shock and vibration impacts on the construction machine (<NUM>) from being transferred to one or more inertial sensors, comprising:
a core (<NUM>); and
one or more inertial sensors (<NUM>) attached to the core;
a pocket (<NUM>) in which the core (<NUM>) is disposed;
a lid (<NUM>) covering the core;
a plurality of elastomer insertions (<NUM>) attached to the core (<NUM>) forming an upper wedge (<NUM>) between the core (<NUM>) and the lid (<NUM>) and a lower wedge (<NUM>) between the core (<NUM>) and the pocket (<NUM>); and
a coupler (<NUM>) providing controlled connection of the pocket (<NUM>) and the lid (<NUM>) to compress the plurality of elastomer insertions (<NUM>) using a force corresponding to a target resonance frequency for the inertial sensor suspension apparatus (<NUM>).