This invention relates to a position measuring apparatus for an underground excavator, which is useful in measuring a position of excavation by the underground excavator, such as a pipe-jacking machine or a shield machine, which is advancing in the ground while excavating a tunnel, to an optical deflection angle measuring apparatus for measuring with lights a deflection angle between two line segments connecting a cardinal point to respective points set on opposite sides of the cardinal point with distances left from the cardinal point, and also to a position measuring apparatus for an underground excavator, which by using this optical deflection angle measuring apparatus, measures a position of excavation by the underground excavator advancing along a curved path.
For an underground excavator such as a pipe-jacking machine or a shield machine which advances in the ground while excavating a tunnel, it is necessary to enable the excavator to accurately advance along a planned line which is a preset advancing route. For this purpose, it is desired to make it possible to measure the current position of the advancing underground excavator in real time and accurately. Namely, if the underground excavator begins to advance off the planned line, an operator can quickly find out this problem and can take a countermeasure at an early stage if the operator is provided in real time with highly-reliable information on the current position of the underground excavator. Control can therefore be performed with ease to make the underground excavator advance along the planned line, and improvements in the accuracy of the work can also be expected. As techniques for measuring a position of excavation by an underground excavator, a variety of methods have been used to date including a method in which xe2x80x9ca measurement is performed manually by using a transitxe2x80x9d, a method in which xe2x80x9ca position of excavation by an underground excavator is measured by arranging an oscillating coil, which generates an induction field, on the underground excavator and measuring the intensity of the induction field with a receiving coil arranged on the groundxe2x80x9d, and a method in which xe2x80x9ca position of excavation by an underground excavator is measured by laying a cable way conversely on the ground, causing a current to flow through the cable way to generate an induction field, and detecting the intensity of the induction field with a receiving coil arranged on the underground excavatorxe2x80x9d. However, these conventional techniques for the measurement of positions of underground excavators are inherently incapable of performing real-time measurements of positions of excavation or, even if such real-time measurements are feasible theoretically, can hardly be put into practical use.
As a position measuring technique for an underground excavator, which can reduce these problems, a direction detecting apparatus for a shield machine has been proposed as disclosed in JP 61-45092 A. This direction detecting apparatus for the shield machine, which has been proposed previously, is an apparatus in which xe2x80x9ca first laser beam oscillator for performing radiation into a forward tunnel and a first laser beam receiver capable of receiving a laser beam from a front are mounted on a base such that they can be turned in an X direction (yawing direction) and an Y direction (pitching direction) by servomotors, a measuring instrument capable of detecting their turned angles by sensors is arranged in an entrance section to the tunnel, a second laser beam oscillator for performing radiation toward a first laser beam receiver at a rear, a second laser beam receiver capable of receiving a laser beam from the first laser beam at the rear and a third laser beam oscillator for performing radiation toward the shield machine at a front are arranged on a base such that they can be turned in the X direction and the Y direction by servomotors, a measuring relay designed to detect their turned angles is arranged in an intermediate section of the tunnel, and a third laser beam receiver and a pitching-rolling meter, which can receive a laser beam from the second laser beam oscillator at the rear and can detect the X and Y directions and a rolling angle, respectively, are arranged on the shield machinexe2x80x9d.
Upon performing construction work on the ground or under the ground, it is necessary to determine an angle relationship between two line segments which connect a point, which serves as a cardinal point, to points set on opposite sides of the cardinal point with distances left from the cardinal point. Upon constructing a curved or bent road, it is necessary to determine the angle of the curved or bent part of the road surface under construction. In this case, a measurement point which serves as a cardinal point is set at a suitable place in the curved or bent part, measurement points are also set in road-surface working zones on the opposite sides of the cardinal point with distances left from the cardinal point, and an angle between line segments connecting the measurement point as the cardinal point to the respective measurement points on the opposite sides of the cardinal point is measured. To excavate a curved tunnel by an underground excavator, the position of excavation must be ascertained to determine whether or not the underground excavator is accurately advancing along a planned route (preset advancing route). In this case, it is also necessary to determine an angle relationship between line segments connecting a measurement point, which serves as a cardinal point, to respective measurement points on opposite sides of the cardinal point, as will be described in detail subsequently herein. To determine an angle relationship between line segments on opposite sides of such a cardinal point as an apex, either an interior angle or an exterior angle of both the line segments can be measured, and this object can be achieved if a value concerning such an angle as enabling to automatically specify the angle relationship can be measured. In this specification, a value concerning such an angle as enabling to specify the angle relationship between such two line segments is called a xe2x80x9cdeflection anglexe2x80x9d.
In construction work, a measuring method making use of a transit has been adopted to date in general to measure such deflection angles. As this measuring method of a deflection angle by a transit is a method which relies upon human ability, it requires labor such as a skilled worker and moreover, takes a long time for each measurement. In addition, a turning mechanism is required to turn a telescope in a yawing direction (horizontal direction) and a pitching direction (vertical direction), so that mechanical measurement errors tend to occur due to this turning mechanism, thereby making it difficult to assure high measuring accuracy. Furthermore, if external force such as that causing tilting in the yawing direction and/or pitching direction, such as vibrations, is applied, a measurement error takes place by such external force, thereby affecting the results of the measurement.
Incidentally, upon excavating a curved tunnel by an underground excavator which advances in the ground while excavating a tunnel, the position of excavation by the underground excavator is measured so that the underground excavator can accurately advance along a planned route. Examples of underground excavators of this type can include small-diameter pipe-jacking machine for burying in the ground small-diameter pipes which men cannot enter and semi-shield and shield machines for burying in the ground large-diameter pipes which men can enter. To measure the position of excavation by such an underground excavator, it is the general practice to set a measuring start point and a measuring end point at a positionxe2x80x94which serves as a start pint for excavation by the underground excavator, such as a starting shaftxe2x80x94and within the underground excavator, respectively, and also to set a suitable number of intermediate measuring points between the measuring start point and the measuring end point as the excavation by the underground excavator proceeds. By measuring distances between these measuring points and also measuring deflection angles between line segments connecting each intermediate measuring point and its adjacent measuring points on opposite sides of the intermediate measuring point, the position of excavation by the underground excavator is determined by computation on the basis of the results of these measurements. When measuring such deflection angles in the course of the measurement of positions of excavation by the underground excavator, the method in which measurements are performed by a transit has also been adopted to date. The method which makes use of a transit, however, takes a long time for each measurement and requires labor as mentioned above and, especially when measurements are performed in a narrow tunnel, the measurement work involves a great deal of labor and danger. As techniques for measuring the position of excavation by an underground excavator of this type, there are techniques which have adopted a method which optically measures a deflection angle by a laser beam without relying upon a transit.
As a representative example of the techniques which had adopted such a method for the measurement of the position of excavation by an underground excavator, the technique disclosed in JP 5-340186 A can be mentioned by way of example. According to the technique disclosed in JP 5-340186 A (hereinafter called xe2x80x9cthe conventional techniquexe2x80x9d), xe2x80x9ca laser aiming system having an angle measuring function is arranged in front of a rear collimation point set in a curved tunnel, a position detecting element (photoelectric element) provided with a miniature reflecting prism is arranged as a target within a shied machine, and a suitable number of wedge prismsxe2x80x94each of which is equipped with a range finder capable of measuring the direction change angle of a laser beam obtained by refracting a laser beam from the laser aiming systemxe2x80x94are arranged as the excavation by the underground excavator proceeds.
Upon measuring the position of excavation by an underground excavator by this conventional technique, each wedge prism is caused to turn by a remote operation such that a laser beam from a laser aiming system is always directed through the wedge prism onto a target in the shield machine. As the laser beam from the laser aiming system, which has been transmitted through the wedge prism, is directed onto the position detecting element as the target, the position of a laser spot can be detected, the deflection angle at the point where the wedge prism is arranged is measured by the quantity of turning of the wedge prism, and the distance between the individual measuring points is also measured by the range finder of the wedge prism. According to this conventional technique, the position of excavation by the underground excavator is measured in terms of coordinate positions on the basis of the distances between the respective measuring points, the deflection angle and the position of the laser spot obtained as described above.
According to the former conventional apparatus, the laser beam oscillator is caused to turn in the yawing direction and/or the pitching direction such that a laser beam, which is a laser light of a high convergence degree, is irradiated to a predetermined position on a laser beam receiver. The turned angle or angles are detected, and based on the turned angle or angles so detected, the position of the shield machine offset from the planned line is computed and determined by a computer. Upon measuring the position of excavation by the underground excavator, an operation for turning the laser beam oscillator to precisely direct a laser beam to the predetermined position on the laser beam receiver is therefore needed. This makes the operation complex and moreover, requires a turning mechanism for turning the laser beam oscillator, such as servomotors, thereby also making the mechanism complex. As a consequence, various problems have arisen. For example, because of the provision of such a turning mechanism, the apparatus becomes too large as one to be arranged in a tunnel, and needless to say, requires higher manufacturing cost. As the turning mechanism is a mechanical one, mechanical errors are added to optical errors, thereby making it difficult to assure high measuring accuracy and also making the apparatus weak against vibrations.
On the other hand, the deflection angle measuring technique which is adopted in the latter conventional technique is a method in which a deflection angle is optically measured by a laser beam. Of the problems observed on the above-mentioned method making use of a transit, the problem that measurement errors occur due to mechanical measurement errors by the turning mechanism and external force such as vibrations therefore still remains unsolved, although the problems caused by the dependence on human ability, such as the need for labor and the requirement of a long time for each measurement, have been reduced. Described specifically, according to the deflection angle measuring technique making use of this conventional technique, to always direct a laser beam from the laser aiming system, said laser beam being a laser light of a high convergence degree, onto the position detecting element as a target by a turning operation of the wedge prism, the turning mechanism is required. Like the method making use of a transit, mechanical measurement errors tend to occur due to the turning mechanism, thereby making it difficult to assure high measuring accuracy.
Furthermore, according to the deflection angle measuring technique making use of this conventional technique, an application of external force, such as that causing tilting in the yawing direction or the pitching direction like vibrations, to the laser aiming system, the wedge prism or the target results in a measurement error by the external force, so that the measurement results of a deflection angle are affected significantly. This external force, such as vibrations, is applied by vibrations of street traffic or construction work, wind force or the like on the ground or by yawing or pitching of an underground excavator or vibrations due to excavation by the underground excavator or falling of earth in the ground. Especially in the measurement of the position of excavation by the underground excavator, the measurement results of a deflection angle affects the measurement results of the position of excavation to a considerable extent and moreover, there is a high degree of need for the accurate measurement of deflection angles because such deflection angles are often measured at gently curved places. When a measurement error takes place due to a mechanical measurement error associated with the turning mechanism or external force such as vibrations, the measurement results of the position of excavation by the underground excavator are affected considerably.
The present invention is intended to eliminate these problems which are observed on the conventional techniques, and has as a first object the provision of a position measuring apparatus for an underground excavator, which upon measuring a position of excavation by the underground excavator, does not need an operation for directing a light onto light-receiving means and hence does not require any mechanism for such an operation.
Further, the present invention also has as a second object the provision of an optical deflection angle measuring apparatus which upon optically measuring a deflection angle, does not require an operation for directing a light onto a position detecting element and prevents external force such as vibrations, even when applied, from affecting the measurement results.
The first object of the present invention is achieved by a position measuring apparatus for an underground excavator, said apparatus being useful in measuring a position of excavation by the underground excavator advancing in the ground while excavating a tunnel and being adapted to measure a position of a measured point, which is arranged at a front in an excavating direction and serves as an indication for the position of excavation, on a basis of its positional relationship with a measuring cardinal point arranged at a rear in the excavating direction and serving as a cardinal point for the measurement, comprising:
a cardinal-point measuring unit for setting the measuring cardinal point, said cardinal-point measuring unit having a light source capable of emitting a diffuse light forward, converging means capable of converging a diffuse light from a forward light source, and light-receiving means arranged such that the light-receiving means can receive a light converged by the converging means and can detect a direction of the forward light source on a basis of a position of the light so received;
a measured-point measuring unit for setting the measured point, said measured-point measuring unit having a light source capable of emitting a diffuse light rearward, converging means capable of converging a diffuse light from a rear light source, and light-receiving means arranged such that the light-receiving means can receive a light converged by the converging means and can detect a direction of the rear light source on a basis of a position of the light so received;
at least one intermediate measuring unit arranged between the cardinal-point measuring unit and the measured-point measuring unit in the tunnel and having a light source capable of emitting diffuse lights forward and rearward, converging means capable of converging diffuse lights from forward and rearward light sources, respectively, and light-receiving means arranged such that the light-receiving means can receive respective lights converged by the converging means and can detect directions of the forward and rearward light sources on a basis of positions of the respective lights so received; and
computing means for computing and measuring a position of the measured point relative to the measuring cardinal point on a basis of data, which are concerned with the directions of the respective light sources as determined based on detection results at the respective measuring units consisting of the cardinal-point measuring unit, the measured-point measuring unit and the intermediate measuring unit, and data on distances between the individual measuring units and their adjacent measuring units.
Owing to the adoption of these technical means in the position measuring apparatus of the present invention for the underground excavator, the intermediate measuring unit converges by converging means diffuse lights from the front and rear light sources of the adjacent measuring units located at the front and rear of the intermediate measuring unit, the thus-converged lights are received by the corresponding light-receiving means, directions of the front and rear light sources relative to the intermediate measuring unit can be detected based on the positions of the respective lights so received, and data on the directions of the individual light sources can be obtained based on the detection results. In this case, the light sources capable of emitting diffuse lights are used as light sources, and the diffuse lights from the light sources are converged by the converging means and are directed onto the light-receiving means. Unlike the conventional art, it is therefore unnecessary to perform an operation for directing a light from each light source onto its corresponding light-receiving means. Once the data on the directions of the respective light sources are obtained as described above, the angles of individual advancing routes, which connect the adjacent measuring units with each other, relative to a starting direction line can be indirectly determined by computation without directly detecting them from their relationships with the starting direction line. In this case, even when the intermediate measuring unit and the measured-point measuring unit deviate depending on their spatial positions upon mounting or deviate depending on yawing or pitching while the underground excavator is advancing, the angles can be accurately determined under conditions with such influence excluded. If data concerning the distances between the individual measuring units and their adjacent measuring units are separately collected by a suitable method, the position of the measured point relative to the measuring cardinal point can be computed and measured from the above-described data on the respective angles as determined by computation and also from the data on the respective distances.
The second object of the present invention is achieved by an optical deflection angle measuring apparatus for measuring with lights a deflection angle between two line segments connecting a cardinal point to respective points set on opposite sides of the cardinal point with distances left from the cardinal point, comprising:
deflection-angle measuring light sources for emitting diffuse lights, said deflection-angle light sources being arranged at the respective points set on the opposite sides of the cardinal point; and
a deflection-angle measuring detector arranged at the cardinal point and provided with:
a common converging means for converging at least portions of the diffuse lights from the respective light sources,
position detecting elements for receiving the lights, which have been emitted from the respective light sources and have been converged by the converging means, and detecting received positions of the converged lights, and
light-direction changing means for changing direction of at least portions of the diffuse lights from the respective light sources, which are about to enter the converging means, such that the at least portions of the diffuse lights are allowed to be transmitted and lights, which have been emitted from the respective light sources and have then been converged by the converging means, are guided to the corresponding position detecting elements;
wherein the respective position detecting elements are arranged at positions where the position detecting elements do not block the diffuse lights from the respective light sources, said diffuse lights being about to enter the converging means, whereby the deflection-angle measuring detector is constructed and a deflection angle between optical axes of the respective light sources can be calculated by computation on a basis of results of detections by the respective position detecting elements.
The optical deflection angle measuring apparatus according to the present invention, upon optically measuring a deflection angle, does not require an operation for directing a light onto each position detecting element unlike the case making use of laser beams as light sources, because as described above, the light sources capable of emitting especially diffuse lights are used as the deflection angle measuring light sources, which are arranged at the respective points set on the opposite sides of the cardinal point, to permit illumination of wide areas with spread lights and coupled with this, the spread lights from the respective light sources are converged by the converging means and received at the corresponding position detecting elements to determine the received positions of the lights and the deflection angles between the optical axes of the individual light sources can be obtained based on the respective detection results. Further, the light direction changing means are arranged to transmit at least portions of the diffuse lights from the respective light sources, said diffuse lights being about to enter the converging means, and also to change the directions of the lights form the respective light sources, said lights being about to be converged by the converging means, such that the thus-converged lights are guided to the corresponding position detecting elements, and the individual position detecting elements are arranged at positions where the, individual position detecting elements do not block the corresponding diffuse lights which are about to enter the converging means. The incidence of the diffuse lights from the corresponding light sources into the converging means is therefore not prevented by the corresponding position detecting elements. It is accordingly not required to provide each light source with its own converging means for converging a diffused light, and a common converging means can be used for the light sources. Owing to these features, even when external force such as vibrations in the pitching or yawing direction is applied to the deflection angle measuring detectors or light sources, the measurement results of the deflection angle are not affected by such external force. Moreover, the measurement results of the deflection angle are not affected by the spatial positions of the mounted detectors and light sources insofar as the setting of positions is accurately conducted upon mounting the detectors and light sources.