Patent Description:
Detecting underground objects is a challenge since such objects are not visible to the human eye. Such underground objects may also present a threat. Underground objects include, for example, buried rocks, underground cavities, air pockets, and archaeological artifacts (e.g., buried buildings, buried mills and the like). Underground objects may also be changes in ground composition which may pose a threat to heavy equipment and personnel, such as muddy terrain, swamps, quicksand and the like.

A known method for detecting underground objects is seismic mapping. In this method, devices known as geophones, which can detect and record seismic responses of the ground over time are positioned in the ground in an area of interest. Geophones are in general inserted into the ground and set up in an array format. One or more seismic sources are then used to generate seismic waves over a period of time in the area of interest. The seismic sources can be manually or hydraulically activated hammers. The seismic waves are substantially reflected and diffracted by objects, open spaces and general differences in ground composition. The geophones which were placed in the ground are synchronized with one another and detect the seismic responses of the area of interest based on the reflections and diffractions of the seismic waves received. Algorithms are then used to extract the underground structure of the area of interest as well as the presence and position of any objects or open spaces in the ground. These algorithms substantially reconstruct a map of the ground under the area of interest.

<CIT>, entitled "Alternative vibrator actuator source", directs to a vibratory seismic source for delivering acoustic energy into the earth. The acoustic energy is to be sensed by geophones for seismic prospecting. The source includes a plurality of linear motors arranged in a grid. Each linear motor includes a rod. Each rod is arranged to move vertically to contact the ground with a lower end of the rod. A control system controls the movement of the rods such that movement of the rods is synchronized with each other and the rods vibrate the ground and deliver acoustic energy thereto.

<CIT>, entitled "Seismic Source/Receiver Probe for Shallow Seismic Surveying" directs to a systems for evaluating underground structures and objects, particularly relatively shallow underground structures and objects, using a unitary apparatus including a seismic source and a receiver transducer within a common housing or frame. A unitary seismic probe includes a ground contacting structure that incorporates a wedge or a blade and an actuator attached to the ground contacting structure. The actuator includes a solenoid, a spring, a hammer and a stop structure attached to one end of the ground contacting structure. A Sensor is attached to the ground contacting structure at an opposite end. The probe assembly, functions to both generate a pressure wave into the ground, and to sense the ground for resulting wave motion. The probe is positioned such that the blade or wedge is in contact with the ground. With the solenoid de-energized, the spring lifts the hammer up. Once the solenoid is energized, the resulting magnetic field reacts with the hammer, forcing it down and compressing spring, until the end of the hammer strikes an anvil. The sensor measures the resulting vibrations in the soil.

<CIT>, entitled "Device and Method for Continuous Data Acquisition" directs to a seismic source mounted on a truck, which includes a baseplate. The baseplate includes wheels for staying in contact with the ground while the truck moves along an acquisition line, so that the acoustic energy is continuously imparted to the ground. Sensors or receivers are used to record the reflected energy and may include hydrophones, geophones and/or accelerometers. Sallas et al directs to a method for separating source signal from received signal based, in part, on an optimal least square filter solution (e.g., Weiner-Kolmogorov filter) in the presence of white noise, applied in the frequency domain.

<CIT>, entitled "Seismic Prospecting with a Continuous Seismic Source", directs to a continuous seismic source in the form of a drum being towed by a truck. The drum source is towed by a vehicle. Conventional detectors or geophones are disposed in an array and are interconnected by wires. The output from the array enters a signal-conditioning unit, which amplifies the signal. The signal is than transmitted by a radio transmitter which codes and modulates the signal. The signals transmitted from the several arrays are received in the towed vehicle by a receiver. These received signals are multiplexed and relayed to a base office. The signals received at the base office are correlated by a correlator, which multiplies each sample of the source signal by the corresponding sample of each array signal and by each of the following samples of each array signal, up to a limit incorporated in the device and representing the maximum seismic travel-time of interest.

<CIT> as well as US Patents <CIT> and <CIT> disclose systems for seismic investigations that are mounted on vehicles and are operable when the vehicles are not in motion.

US Patent <CIT> teaches a seismic unit that is operable when mounted on a moving vehicle. By the use of a collection of elements contained within a rolling drum, non-focused seismic waves may be generated.

It is an object of the disclosed technique to provide a novel seismic source apparatus. In a first of its aspects, the invention provides a seismic source apparatus, configured to be maneuvered by a vehicle over a terrain and operable on the move, i.e., while the vehicle is in motion, said seismic source apparatus comprising:.

Also provided is a seismic source apparatus, configured to be maneuvered by a vehicle over a terrain and operable while in motion, said seismic source apparatus comprising:.

As disclosed herein, seismic surveying studies, method of seismic measurements or any other methods of the invention, as well as any of the apparatuses and systems of the invention are configured, operable and implemented to carry out the seismic investigation while the vehicle carrying the seismic source unit or a vehicle pushing or pulling a platform carrying the seismic source unit is on the move, namely is in motion. The terms suggest carrying out a seismic measurement while the vehicle carrying the seismic source unit is moving along a path on the terrain while the seismic waves are generated and the seismic measurement is carried out. Putting it differently, neither the vehicle nor the source platform is in a state of arrest or at a stationary status when the seismic waves are generated or detected.

Despite the vehicle or platform being on the move, the energy transfer element maintains a continuous and intimate contact with the terrain. In other words, the element remains in contact with the terrain throughout the travel route along which seismic waves are generated and detected. The expression "intimate contact" means a direct non-mediated contact between the outer surface of the energy transfer element, being in some embodiments a source drum, as defined, and a region of the terrain on which the element travels. An intimate contact is maintained despite holes or crevices or elevations or bumps and the like on which the element travels. To permit such a contact, the energy transfer unit is of a size that enables following the fine contour of the terrain. By utilizing an energy transfer element that maintains intimate contact with a region of the terrain, the present configuration of a system of the invention enables movement over the terrain that is uninterrupted while the seismic wave is generated and travels through the energy transfer element to the ground, permits for continuous generation and detection of seismic waves, and at the same time, effectively isolates the platform or vehicle from vibrations generated during seismic wave generation, by providing a decoupling assembly or elements that are provided between the energy transfer element and the platform or vehicle.

This unique configuration provides a seismic apparatus that is operable while the carrier vehicle is in motion.

As stated herein, the motion of the seismic source unit while the vehicle is in motion or on the move is said to be independent of the motion of said vehicle and/or said source platform. In other words, while the seismic source unit is pulled or pushed or otherwise carried by a moving vehicle or platform along a certain path and is therefore bound to the path traveled by the vehicle or platform, the seismic source unit has a degree of motion freedom to rotate about an axis, tilt, be raised or lowered to remain in contact with the retrain, all while moving along or about at least one selected axis, e.g., that is determined inter alia by the travel path of the vehicle or platform, within a predetermined range. As demonstrated in the figures, the energy transfer unit, being in some configuration a source drum, is coupled with the vehicle or platform and using the decoupling assembly to translate, rotate or both, about at least one of X, Y or Z axis of a reference coordinate system, at least within a selected or predetermined range (e.g., rotate within a range of angles, translate within a range of distances); thus exhibiting degrees of motion freedom from the vehicle and any unit mounted thereof.

In some configurations of an apparatus of the invention, the energy transfer element is a source drum, configured to translate, rotate or tilt while moving on the terrain.

As disclosed herein, the seismic source unit includes one or more masses (or weights), one or more masses, in a form of a double ended piston with the masses attached to ends thereof or in a form of an electromechanical unit. The double ended piston may be an hydraulic piston or a pneumatic piston.

In some embodiments, the seismic source unit includes a hammer and an anvil coupled with said energy transfer element, said hammer being configured to strike said anvil.

The hammer includes a hammer head and two track rollers mounted on a track rollers axis and over a camshaft,.

The motion de-coupling assembly may comprise a <NUM>-link suspension. In some configurations, the motion de-coupling assembly includes at least one decoupling element selected from a <NUM>-link suspension, a universal joint, a suspension piston and a push-pull spring.

In some embodiments, the source platform is a towed cart coupled with said vehicle via said motion de-coupling assembly. In some embodiments, the source platform is mounted on one of a manually maneuvered vehicle, a remotely maneuvered vehicle, a towed vehicle or cart and an independently maneuvered vehicle.

In another aspect of the technology disclosed herein there is provided a system comprising a vehicle or a moving platform, a seismic source apparatus according to the invention that is mounted on said platform or vehicle and one or more seismic detection unit.

The seismic detection unit may be any such detection unit known in the art. In some embodiments, the detection unit is or comprises a laser source. The laser source may be a multibeam source. In some embodiments, the laser source is or comprises a plurality of laser beams.

In some embodiments, the laser source is configured to illuminate an area of interest of the terrain. In some embodiments, the laser source directs a plurality of laser beams to generate an assemblage of laser spots on the area of interest.

Also provided is a method for generating a seismic map of a terrain region, the method comprising:.

As known in the art, a seismic map or seismic data refers to information relating to the amplitude, frequency and phase of a seismic wave, which propagates through a region of interest, as manifested by vibrations in the region of interest, and specifically of tilt vibrations, as a function of distance from a detector and time. The system of the invention enables to remotely generate a seismic map for a region of interest without an imager being in physical contact with the ground at the region of interest. The seismic map may be a single point, a 1D map or a 2D map of the region of interest and can be employed to detect underground objects.

In some embodiments, the detection unit is or comprises a laser source as disclosed herein. The laser source may be a multibeam source. In some embodiments, the laser source is or comprises a plurality of laser beams.

In methods of the invention, the step of detecting comprises detecting of seismic waves that are reflected or diffracted or by detecting a seismic interaction of the seismic waves with by objects, open spaces and modulations in ground composition.

Further described is a motion decoupling assembly for use in a seismic source apparatus. The motion decoupling assembly comprises a seismic source unit and a seismic detection unit, the motion decoupling assembly comprising one or more decoupling elements associating said seismic source unit to a moving platform or vehicle carrying said seismic detection unit, wherein the motion decoupling assembly is configured to isolate said seismic detection unit from vibrational energy generated by said seismic source unit,.

The assembly may be such that the one or more decoupling elements are selected from a <NUM>-link suspension, a universal joint, a suspension piston and a push-pull spring.

Embodiments, descriptors and embodiments of the above are further provided below and are generic and encompass other configurations and permutations which enable apparatuses, systems and methods of the invention.

The disclosed technique overcomes the disadvantages of the prior art by providing a seismic source apparatus which includes a seismic source unit. The seismic source is mounted on a source platform, which is maneuvered over terrain. For example, the source platform is maneuvered (e.g., towed, pushed or side pushed) by a vehicle, where the vehicle may include a seismic surveying system. Alternatively, the source platform unit independently maneuvers over the terrain, for example, the source platform is mounted on a manually maneuvered vehicle, a remotely maneuvered vehicle or an independently maneuvered (e.g. robotic) vehicle. In general, seismic source units include an energy transferring element, such as a hammer face, a rolling drum or a platform, and a seismic energy source such as a movable mass or an ultrasound transducer.

The movable mass may be defined as an object, one, or more, having a predefined mass, which is positioned within the seismic source unit, and may apply force due its mass and/or motion, directly, or indirectly, on an energy transfer element. The moveable mass may apply force, thus, transferring energy, to the energy transfer element continuously, or along predefined intervals (e.g. defined in advance, or on spot decisions).

The energy transfer element is an element that may be configured from one, or a plurality of subsections, which are configured to receive the energy received from the moveable mass (one, or more), and subsequently transfer the energy received, or part thereof, by applying the force on the terrain. The energy transfer element transfers the energy produced by the seismic source unit to the ground. In operation, when the seismic source unit transfers energy to the ground, the seismic source apparatus generates mechanical vibrations and motions. These mechanical vibrations and motions may be transferred to the source platform. Accordingly, when the source platform is maneuvered by a vehicle, which includes a seismic surveying system, these mechanical vibrations and motions may be transferred to the vehicle and thus to the seismic surveying system. Consequently, they may hinder the detection of seismic waves. To maximize the transfer of energy to the ground, the energy transferring element should be in continuous contact with the ground, regardless of the terrain (e.g., holes, crevices, elevations and the like) over which the source moves.

A seismic source apparatus configured to be maneuvered by a vehicle over terrain according to the disclosed techniques includes at least one seismic source unit mounted on a source platform, the seismic source unit is configured to generate seismic waves, and comprises at least one motion de-coupling assembly, which is provided to reduce or prevent vibrational energy generated by the seismic source unit to be transferred to the source platform, and wherein the at least one motion de-coupling assembly is configured to enable motion of said seismic source unit while the vehicle is in motion or on the move, independent of the motion of said vehicle, said source platform, or both, along and/or about at least one axis, at least within a determined range.

As used herein, the vibrational energy is generated by way of vibrations formed due to the operation of the seismic source unit and which are typically directed at all directions, including at the direction of the platform or vehicle on which a detection unit is mounted. Thus to reduce, minimize or prevent the vibrations or vibrational energy from reaching the detection unit, decoupling assemblies or decoupling elements are used. By placing the decoupling elements at specific regions of a system of the invention, as defined, the detection unit is shielded or isolated from such traveling vibrations, enabling continuous and uninterrupted detection of the seismic waves.

As further elaborated below, a motion de-coupling assembly may be implemented, for example, with a parallel <NUM>-link suspension, a spring, a suspension piston, a rotary joint, a universal joint, a bellow joint, a bearing or a hinge. Thus, while the seismic source apparatus is mechanically maneuvered over the terrain, the seismic source unit is in continuous contact with the ground, with degrees of motion freedom relative to the source platform or vehicle. Consequently, transfer of mechanical vibrations and motions from the seismic source unit to the source platform, or vehicle and to the seismic surveying system mounted thereon, is reduced or prevented.

It is noted that a seismic source apparatus according to the present invention may be included in a system comprising a seismic detection unit, and the seismic detection unit which may be a laser source, an array of lasers or any other detection means as known in the art.

Reference is now made to <FIG>, which is a schematic illustration of an exemplary seismic surveying system, generally referenced <NUM>, employed to detect and image underground objects, constructed and operative in accordance with another embodiment of the disclosed technique. <FIG> depicts a typical scenario in which a system according to the disclosed technique is employed. System <NUM> includes a seismic source unit <NUM>, a multibeam laser source <NUM> and an imager <NUM>. Multibeam laser source <NUM> and imager <NUM> are mounted on vehicle <NUM> and seismic source unit <NUM> is mounted on a cart <NUM> (i.e., the source platform is a cart), which is towed by vehicle <NUM>. Multibeam laser source <NUM> and imager <NUM> may be mounted on a controlled gimbal on vehicle <NUM> (e.g., on a mast attached to vehicle <NUM>) such that the multibeam laser source <NUM> and imager <NUM> may be directed toward a selected azimuth and elevation directions. Vehicle <NUM> is associated with a reference coordinate system <NUM>.

In some embodiments, the detection unit used in systems of the invention is or comprises a laser source which may generate a single beam or a multibeam that is directed at various points of an area of the terrain to be surveyed. In some embodiments, the laser source is configured to illuminate an area of interest of the terrain. In some embodiments, the laser source is or comprises a plurality of laser beams. Irrespective of the form or selection of laser sources used, the laser source is configured and operable to direct a plurality of laser beams to generate an assemblage of laser spots on the area of interest.

In some embodiments, the laser source is a multibeam laser source. A multibeam laser source may any such source known in the art. An exemplary multibeam source is subject of International Patent Application No. <CIT>, or any US counterpart or national phase application thereof.

In <FIG>, seismic source unit <NUM> is depicted as being mounted on a cart <NUM> being towed by vehicle <NUM>. It is noted that this is an example only, which is brought herein for explanatory purposes only. In general, the seismic source unit <NUM> may be maneuvered (e.g., towed, pushed or side pushed) by vehicle <NUM>.

In operation, vehicle <NUM> drives or is maneuvered along a road <NUM>. As shown in <FIG>, ground <NUM> includes a plurality of underground objects such as a rock <NUM>, an ancient wall <NUM> and a plurality of rocks 172A, 172B and 172C. As vehicle <NUM> drives along the road <NUM>, the seismic source unit <NUM> generates at least one seismic wave <NUM> in the ground <NUM>. Seismic wave <NUM> propagates in the ground <NUM>, including an instantaneous area of interest <NUM>. The multibeam laser source <NUM> illuminates an instantaneous area of interest <NUM> by directing a plurality of laser beams to generate an assemblage of laser spots (not labeled in <FIG>). The assemblage of laser spots covers (i.e., at least substantially) the surface of the instantaneous area of interest <NUM> as demarcated by a set of dotted lines <NUM>. System <NUM> scans the area of interest with laser spot assemblage as the vehicle <NUM> progresses along the road <NUM>. As the vehicle <NUM> progresses along the road <NUM>, imager <NUM> receives speckle patterns corresponding to each laser spot in the assemblage of laser spots as demarcated by a set of dotted lines <NUM> and acquires a defocused image of the received speckle patterns. The general configuration of the multibeam laser source <NUM> and the imager <NUM> can be referred to as an optical geophone array which is capable of detecting the presence of seismic waves at a very high resolution and sensitivity. This in turn enables the system <NUM> depicted in <FIG> to be used in real-time seismic surveying.

As mentioned above, the seismic source unit <NUM> is mechanically maneuvered by the vehicle <NUM>. According to the disclosed technique, the seismic source and vehicle <NUM> exhibit degrees of motion freedom therebetween, such that the vibrations and motions induced on the multibeam laser source <NUM> and imager <NUM> by the seismic source unit <NUM> are reduced (e.g., relative for to the vibrations and motion induced when seismic source is mounted on vehicle <NUM> or when no such degrees of motion freedom exist) or prevented. As further elaborated below, the seismic source unit <NUM> includes a source drum. The source drum is coupled with cart <NUM> such that the source drum is able using a de-coupling assembly (not shown) to either translate, rotate or both, about at least one of Xv, Yv or Zv axis of a reference coordinate system <NUM>, at least within a selected or predetermined range (e.g., rotate within a range of angles, translate within a range of distances). Thus, the source drum exhibits degrees of motion freedom from the vehicle <NUM>, and thus from the multibeam laser source <NUM> and the imager <NUM>.

Reference is now made to <FIG> and <FIG> which are schematic illustration of a portion of an exemplary seismic source apparatus, generally referenced <NUM>, constructed and operative in accordance with another embodiment of the disclosed technique. It is noted that only a portion of seismic source apparatus <NUM> is depicted in <FIG> for clarity of the figures and the explanations. Seismic source apparatus <NUM> may be employed in any scenario described herein above, for example in conjunction with <FIG> or when the seismic source apparatus is mounted on a vehicle.

In seismic source apparatus <NUM>, the energy transfer element comprises a source drum <NUM> associated with axis of rotation <NUM>, anvil bridge <NUM>, support prongs <NUM><NUM> and <NUM><NUM> and a rotational bearing <NUM>. The seismic source apparatus <NUM> comprises also a de-coupling assembly <NUM> comprising bars <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and rotary joint <NUM>. In some embodiments, the assembly need not include multiple decoupling elements such as bars, springs and rotary joints. In such elements, the decoupling assembly may include one or more decoupling elements, provided that the decoupling element(s) present are sufficient to reduce or prevent vibrational energy from reaching the vehicle or platform, as disclosed herein.

<FIG> and <FIG> do not show a source platform, a moveable mass, or a vehicle.

The source drum <NUM> (shown in the figures in a shape of a moving wheel or a rolling drum) is configured to roll about an axis of rotation <NUM>. The anvil bridge <NUM> is coupled with axis of rotation <NUM> via support prongs <NUM><NUM> and <NUM><NUM> and a rotational bearing <NUM> (e.g., a ball bearing).

Support prongs <NUM><NUM> and <NUM><NUM> are adjoined to de-coupling assembly <NUM>, thus, support prongs <NUM><NUM> and <NUM><NUM> are coupled with plate <NUM> by a parallel <NUM>-link suspension comprising. the parallel <NUM>-link suspension bars <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> by hinge <NUM><NUM> and with plate <NUM> by hinge <NUM><NUM>. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> by hinge <NUM><NUM> and with plate <NUM> by hinge <NUM><NUM>. Bar <NUM> is coupled with support prong <NUM><NUM> by hinge <NUM><NUM> and to plate <NUM> by hinge <NUM><NUM>. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> by hinge <NUM><NUM> and to plate <NUM> by hinge <NUM><NUM>. Consequently, the seismic source apparatus <NUM> is free to vertically move along the Yv axis of coordinate system <NUM>. The seismic source apparatus <NUM> further includes plate <NUM>, coupled with plate <NUM> via springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>. Springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM> enable seismic source apparatus <NUM> to vertically move along the Zv axis of coordinate system <NUM>, as well as to rotate about the Xv axis and the Yv axis. A rotary joint <NUM> is coupled with plate <NUM>, thus enabling seismic source apparatus <NUM> to rotate about the Zv axis of coordinate system <NUM>. Coordinate system <NUM> is associated with either a vehicle or a source platform.

As noted above, de-coupling assembly <NUM>, includes three motion and vibration de-coupling elements, namely the <NUM>-link parallel suspension, springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM> and rotary joint <NUM>. In operation, the seismic source apparatus <NUM> is maneuvered (e.g., by vehicle <NUM> - <FIG>) over terrain <NUM>. Terrain <NUM> may be uneven and include holes, crevices, elevations bumps and the like. However, as described above, the seismic source is free to move along and rotate about the axes of coordinate system <NUM> while maintaining intimate contact with the terrain. For example, the parallel <NUM>-link suspension enables source drum <NUM> to move up and down when source drum <NUM> moves over a bump or a crevice. Thus, the source drum <NUM> remains in contact with the terrain <NUM>. To generate a seismic wave in the ground, while the source drum <NUM> is in contact with the terrain and while the vehicle is in maneuver, the hammer (not shown) strikes the anvil bridge <NUM>, which transfers the energy from the hammer strike, via the support prongs <NUM><NUM> and <NUM><NUM>, to the axis of rotation <NUM>, the source drum <NUM> to the terrain <NUM>. In other words, the source drum <NUM> couples the energy produced by the hammer strike to the terrain <NUM>. Due to the de-coupling assembly <NUM>, during the strike of the hammer, the seismic source apparatus <NUM> may come to a temporary halt, while the vehicle or the source platform maneuvering the seismic source apparatus <NUM> remain in motion. For example, a strike of the hammer can last <NUM> milliseconds (hereafter, "ms"). When the seismic source apparatus <NUM> moves at a velocity of <NUM> meters per second (m/s), the source platform or the vehicle continues to move for about <NUM> millimeters (mm) while the energy transfer element of the seismic source apparatus <NUM> is stationary. The ability of the energy transfer element of seismic source apparatus <NUM> to move along and rotate about the axes Xv, Yv and Zv of coordinate system <NUM>, reduces the motion and vibrations transferred from the energy transfer element of the seismic source apparatus <NUM> to the vehicle or the source platform. Accordingly, de-coupling assembly <NUM> reduces or prevents vibrational energy further transferring through assembly <NUM>, e.g. to a source platform or the vehicle comprising the seismic source apparatus <NUM>. Furthermore, the de-coupling assembly <NUM> sufficiently reduces or prevents vibration energy and motion from vehicle or source platform. Furthermore, the de-coupling assembly <NUM> ensures that the energy transfer element of the seismic source apparatus <NUM> motion and vibration is independent of the motion of said vehicle and/or said source platform. Consequently, in case the seismic source is maneuvered by a vehicle mounted with the seismic surveying system, the vibrations and motions transferred to the seismic surveying system are reduced or even prevented. This permits the seismic source unit to generate seismic waves in a direction substantially perpendicular to the terrain required for surveying a terrain.

With reference to <FIG>, depicted therein is an alternative to springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>. In <FIG>, springs <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM> are replaced with a suspension piston <NUM> and a universal joint <NUM>. Suspension piston <NUM> enable seismic source apparatus <NUM> to vertically move along the Zv axis of coordinate system <NUM>, while universal joint <NUM> enables seismic source apparatus <NUM> to rotate about the Xv axis and the Yv axis.

Reference is now made to <FIG>, which are schematic illustrations of yet another exemplary seismic source apparatus generally referenced <NUM>, constructed and operative in accordance with another embodiment of the disclosed technique. The seismic source apparatus <NUM> may be employed in any scenario described herein above, for example in conjunction with <FIG> or when the seismic source apparatus is mounted on a vehicle and may employ the principles described herein above in conjunction with <FIG> or in any other manner (e.g. when mounted on a platform positioned in front of a vehicle, or in the center of the vehicle, or by any other configuration wherein the apparatus maneuvered by a vehicle).

In seismic source apparatus <NUM>, the movable mass of the seismic source includes a hammer and an anvil as elaborated below, and the energy transfer element is a source drum also as elaborated below. The seismic source apparatus <NUM> includes a seismic source unit <NUM> coupled with a towed cart <NUM> (i.e., towed cart <NUM> is the source platform), such that the seismic source unit <NUM> is able to either translate, rotate or both, relative to either a vehicle or towed cart <NUM> or both i.e., about at least one of Xv, Yv or Zv axis of a reference coordinate system <NUM>. The seismic source unit <NUM> comprises, an energy transfer element which comprises, a source drum <NUM>, axis of rotation <NUM>, two vertical support prongs <NUM><NUM> and <NUM><NUM>, and an anvil <NUM>, ; a moveable mass which comprises hammer <NUM>; and camshaft <NUM>. Hammer <NUM> comprises hammer head <NUM> and two track rollers <NUM><NUM> and <NUM><NUM> mounted on a track rollers axis <NUM> and over camshaft <NUM>. Anvil <NUM> is coupled perpendicularly between vertical support prongs <NUM><NUM> and <NUM><NUM>. Camshaft <NUM> includes a sloped portion <NUM> and an edged portion <NUM>, and is also coupled perpendicularly between vertical support prongs <NUM><NUM> and <NUM><NUM> and at the upper part thereof. Camshaft <NUM> is further operable to rotate about a vertical axis relative to vertical support prongs <NUM><NUM> and <NUM><NUM>. Vertical support prongs <NUM><NUM> and <NUM><NUM> are further coupled with axis of rotation <NUM> of source drum <NUM> via axis rotational bearings. As shall be further elaborated below in conjunction with <FIG>, seismic source <NUM> may be positioned in two configurations, a deployed configuration or a transport configuration. For the sake of the clarity of the description, <FIG> depict seismic source apparatus <NUM> in the transport configuration.

In operation, a motor <NUM> rotates camshaft <NUM>, (i.e., either directly or via gears). As track rollers <NUM><NUM> and <NUM><NUM> roll over the sloped portion <NUM> of camshaft <NUM>, track rollers <NUM><NUM> and <NUM><NUM> rise, thereby raising hammer <NUM> (i.e., via track rollers axis <NUM>) and hammer head <NUM>. When track rollers <NUM><NUM> and <NUM><NUM> reach over edge portion <NUM> of camshaft <NUM>, hammer <NUM> drops, and hammer head <NUM> strikes anvil <NUM>. This strike is referred to herein as a main strike. As can be understood, the time span of the main strike is very short (e.g. <NUM>-<NUM> milliseconds; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>). Anvil <NUM> transfers the energy from the hammer strike, via vertical support prongs <NUM><NUM> and <NUM><NUM>, to axis of rotation <NUM>, source drum <NUM> and to the terrain on which source drum <NUM> rolls. In other words, source drum <NUM> couples the energy produced by the strike of hammer <NUM> to the terrain, via anvil <NUM>, vertical support prongs <NUM><NUM> and <NUM><NUM> and axis of rotation <NUM>. Seismic source <NUM> may further include a spring to aid in accelerating hammer head <NUM> toward anvil <NUM>. It is noted that sloped portion <NUM> aids in preventing a secondary strike of hammer head <NUM> on anvil <NUM>. A secondary strike occurs after a main strike due to energy reflected from the ground back toward anvil <NUM>. This reflected energy cause hammer <NUM> to rise again. During the time period between a main strike and a secondary strike, camshaft <NUM> continues to rotate. If a secondary strike occurs, track rollers <NUM><NUM> and <NUM><NUM> shall be stopped by a section of sloped portion <NUM>, higher than the section to which track rollers <NUM><NUM> and <NUM><NUM> fell during the main strike. As a result, hammer head <NUM> is stopped before it hits anvil <NUM> again.

Seismic source apparatus <NUM> comprises further a de-coupling assembly <NUM>. Seismic source unit <NUM> is coupled with towed cart <NUM> via with de-coupling assembly <NUM>. De-coupling assembly <NUM> comprises the following elements, an arrangement of parallel <NUM>-link suspension bars, a harnessing frame <NUM>, and a push-pull spring <NUM>. The Parallel <NUM>-link suspension includes four bars <NUM><NUM>, <NUM><NUM>, <NUM><NUM> and <NUM><NUM> and a hydraulic arm <NUM>. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> and harnessing frame <NUM> by respective hinges. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> and with harnessing frame <NUM> by respective hinges. Bar <NUM><NUM> is coupled with support prong <NUM><NUM> and with harnessing frame <NUM> by respective hinges. Bar <NUM><NUM> is coupled with vertical support prong <NUM><NUM> and with harnessing frame <NUM> by respective. Consequently, seismic source unit <NUM> is free to vertically move along the Yv axis of the reference coordinate system <NUM>. Also, hydraulic arm <NUM> is coupled with harnessing frame <NUM> and with vertical support prongs <NUM><NUM> and <NUM><NUM> via respective hinges. It is noted that hydraulic arm <NUM>, bars <NUM><NUM> and <NUM><NUM>, and bars <NUM><NUM> and <NUM><NUM> are couple with harnessing frame <NUM> at different respective vertical positions.

Also, towed cart <NUM> includes a push-pull spring <NUM>. Push-pull spring <NUM> enables towed cart <NUM>, and thus seismic source unit <NUM> mounted thereon, to temporarily come to a stop when hammer <NUM> strikes source drum <NUM>, while the vehicle continues the motion thereof. In other words, push-pull spring <NUM> enables towed cart <NUM> (and thus seismic source unit <NUM> mounted thereon), and the vehicle to substantially independent move one with respect to the other along the Zv axis of reference coordinate system <NUM> as well as to rotate one with respect to the other about the Yv axis of reference coordinate system <NUM>. Thus to the configuration of de-coupling assembly <NUM> The ability of seismic source unit <NUM> to move along and rotate about the axes Xv, Yv and Zv of reference coordinate system <NUM>, reduces and/or prevents the motion and vibrational energy transferred to the vehicle from seismic source apparatus <NUM> in general, and due to rough terrain and hammer strikes in particular, and also enables source drum <NUM> to remain coupled with the terrain. Furthermore, during the main strike the de-coupling assembly <NUM> reduces and/or prevents transferring motion and vibrational energy due to a motion of vehicle associated with towed cart <NUM> through push-pull spring <NUM>.

De-coupling assembly <NUM> comprises two motion and vibrational energy de-coupling elements, namely an arrangement of <NUM>-link parallel suspension bars, and push-pull spring <NUM>. For example, seismic source apparatus <NUM> is maneuvered by a vehicle (e.g., vehicle <NUM> - <FIG>) over terrain. Terrain may be uneven and include holes, crevices, elevations bumps and the like. However, as described above, seismic source unit <NUM> is free to move along and rotate about the axes of reference coordinate system <NUM>. For example, the parallel <NUM>-link suspension bars enables source drum <NUM> to move up and down when source drum <NUM> moves over a bump or a crevice. Weights, such as weights <NUM><NUM> and <NUM><NUM> coupled with the vertical support prongs <NUM><NUM> and <NUM><NUM> respectively, push down on source drum <NUM> such that source drum <NUM> remains coupled with the terrain.

As mentioned above, <FIG> depict seismic source unit <NUM> in the transport configuration. In the transport configuration, hydraulic arm <NUM> pulls seismic source unit <NUM> and thus source drum <NUM> such that source drum <NUM> is not coupled with the ground. With reference to <FIG>, seismic source unit <NUM> is depicted therein in the deployed configuration. In the deployed configuration, hydraulic arm <NUM> lowers seismic source unit <NUM> and thus source drum <NUM> until source drum <NUM> is coupled with the ground.

The above examples brought forth in conjunction with <FIG>, <FIG>, and <FIG>, describe several solutions to maintain a mechanical coupling of the seismic source to the ground as well as to decouple the motion of the seismic source from the source platform and/or from a vehicle maneuvering the seismic source. In general, a seismic source apparatus according to the disclosed technique requires a de-coupling assembly decoupling in at least two axes, the vertical axis (Yv) and the longitudinal axis (Zv) of vehicle reference coordinate system. To that end, and in general, a seismic source apparatus includes a de-coupling assembly comprising at least one motion and vibrational energy de-coupler element. A motion and/or vibrational energy de-coupler enables motion of the seismic source along and/or about at least one axis, at least within a determined range. As described above, a motion de-coupler may be implemented, for example, with a parallel <NUM>-link suspension, a spring, a suspension piston, a rotary joint, a universal joint, a bellow joint, a bearing or a hinge.

The hammer, anvil and source drum implementation brought forth in conjunction with <FIG> and <FIG> describes one example of a seismic source units in accordance with the disclosed technique. Another example, typically employed for generating high frequency seismic waves, may be a hydraulic piston mounted within the drum, for example, coupled with the axis of the drum. Also, the width of the drum may be selected based on various operation parameters. For example, the wider the drum wheel, the better are the road and off-road capabilities and the better the frequency coupling with the ground (i.e., the ration between the energy produced by the source and the energy transferred to the ground for frequencies generated by the source). However, maneuverability is reduces with the width of the drum wheel. Also, as the width of the drum wheel increases, the mass of the drum wheel increases, and the natural frequency or frequencies of the drum wheel decrease. As such, the strikes of the hammer may result in uncontrolled vibrations of the drum wheel in these frequencies.

According to another example of the disclosed technique, the seismic source is located on the rotation axis of the source drum, and includes a double ended piston with weights attached to the ends thereof. The piston strikes or vibrates the axis of rotation of the drum as further explained below. Thus, energy is transferred from the axis of rotation of the drum, through the drum to the ground. Reference is now made to <FIG> and <FIG>, which are schematic illustrations of a seismic source apparatus, generally referenced <NUM>, constructed and operative in accordance with a further embodiment of the disclosed technique. Seismic source apparatus <NUM> may be employed in any scenario described herein above, for example in conjunction with <FIG> or when the seismic source apparatus is mounted on a vehicle and may employ the principles described herein above in conjunction with <FIG>, , or <FIG>.

In seismic source apparatus <NUM>, the movable mass of the seismic source unit includes a double ended piston with weights attached thereto as elaborated below, and the energy transfer element is a rolling drum also as elaborated below.

Seismic source apparatus <NUM> includes a source drum <NUM>, a piston apparatus <NUM>, two weights <NUM><NUM> and <NUM><NUM>, and a piston controller <NUM>. Piston apparatus <NUM> is a double ended piston apparatus. Piston apparatus <NUM> includes a piston <NUM> and a cylinder <NUM>, where piston <NUM> is movable within cylinder <NUM>. Weight <NUM><NUM> is coupled with one end of piston <NUM> and weight <NUM><NUM> is coupled with the other end of piston <NUM>. Cylinder <NUM> is coupled with the rotation axis of source drum <NUM>. Source drum <NUM> is rotatably coupled with a source platform <NUM> (i.e., source drum <NUM> can rotate relative to source platform <NUM>). Piston controller <NUM> is coupled with source platform <NUM>.

Piston apparatus <NUM> is, for example, an hydraulic piston apparatus, a pneumatic piston apparatus or an electric piston apparatus. Piston controller <NUM> controls the motion of piston <NUM> in cylinder <NUM>. It is noted that piston apparatus <NUM> is coupled with rotation axis of source drum <NUM> such that the motion of piston <NUM> includes a component in the direction of the Yv axis (i.e., vertical axis) of reference coordinate system <NUM>. As piston <NUM> accelerates in either direction, weights <NUM><NUM> and <NUM><NUM> strike cylinder <NUM> at the end of the motion action thereof. Thus, piston <NUM> and weights <NUM><NUM> and <NUM><NUM> vibrate cylinder <NUM> which transfers the vibratory energy to the rotation axis of source drum <NUM>, and to the ground through source drum <NUM>. In other words, source drum <NUM> couples the energy produced by piston apparatus <NUM> to the terrain over which source drum <NUM> rolls, via the rotation axis of source drum <NUM>.

Also, source platform <NUM> may be coupled with a vehicle via a vehicle interface <NUM>. Source platform <NUM> is coupled with vehicle interface <NUM> via a motion de-coupling assembly <NUM>. In <FIG> and <FIG>, motion de-coupling assembly <NUM> is a <NUM>-link suspension enabling, source platform <NUM> to move in the direction of the Yv axis (i.e., vertical axis) of reference coordinate system <NUM>. Thus, source drum <NUM> remains coupled with the terrain, even when the terrain is uneven and includes holes, crevices, elevations bumps and the like.

Following is an implementation example of seismic source unit <NUM>. Source drum <NUM> is coupled with an outer ring of a rotating barring. Source platform <NUM> is coupled with the inner ring of the rotating barring at one side thereof. Cylinder <NUM> is also coupled with the inner ring of the rotating barring at the other side thereof. Thus, cylinder <NUM> does not rotate with source drum <NUM>. Control connections (e.g., pipes or wires) may pass through the inner ring of the rotating bearing between piston controller <NUM> and cylinder <NUM>.

The embodiment of a seismic source unit described above in conjunction with <FIG> and <FIG> is particularly suitable, but not only, for generating relatively high frequency seismic waves (e.g., up to an order of hundreds of Hertz). Also, this embodiment enables generating a specific waveform accounting for the motion of the vehicle motion, the response of the source drum and ground to the strike and the response of the seismic sensing apparatus. In all of the above embodiments described above, accelerometers may be coupled directly energy transferring elements (e.g., on hammer head <NUM> <FIG>, on anvil <NUM> - <FIG>, on weights <NUM><NUM>, <NUM><NUM> <FIG>), enabling direct measurement of the energy produced and closed loop control on the seismic source. It is noted that seismic source apparatus may be employed with any one of the embodiment described hereinabove in conjunction with <FIG>, <FIG>, <FIG>. For example, seismic source apparatus may be coupled with a vehicle via a parallel <NUM>-link suspension <NUM>, which is similar to parallel <NUM>-link suspensions described above in <FIG> and <FIG>.

Claim 1:
A seismic source apparatus (<NUM>, <NUM>, <NUM>), configured to be maneuvered by a vehicle (<NUM>) over a terrain and operable while in motion, said seismic source apparatus (<NUM>, <NUM>, <NUM>) comprising:
a seismic source unit (<NUM>, <NUM>) mounted on a source platform (<NUM>, <NUM>) and configured to be maneuvered by the vehicle, the seismic source unit (<NUM>, <NUM>) being configured to generate seismic waves while the vehicle is in on the move,
said seismic source unit (<NUM>, <NUM>) including at least one movable mass (<NUM>) and an energy transfer element configured to maintain continuous and intimate contact with the terrain while the vehicle is in motion and the seismic waves are generated;
characterized in that the seismic source apparatus further comprises at least one motion de-coupling assembly (<NUM>, <NUM>, <NUM>) associating said energy transfer element with said source platform (<NUM>, <NUM>) or vehicle (<NUM>), and provided to reduce or prevent vibrational energy generated by said seismic source unit to be transferred to the source platform (<NUM>, <NUM>) or the vehicle (<NUM>),
wherein motion of said seismic source unit (<NUM>, <NUM>) while the vehicle (<NUM>) is in motion is independent of the motion of said vehicle and/or said source platform (<NUM>, <NUM>), wherein the motion of said seismic source unit is along or about at least one selected axis, within a determined range.