CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application No. 19172210.7 filed on May 2, 2019, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a mobile coordinate measuring and/or stake out device that can be hand-held, and relates to a system comprising the device.

BACKGROUND

In order to survey one target point or, in particular, a plurality of target points, numerous geodetic survey devices have been known since antiquity. Here, distance and direction or angle from a surveying device, the absolute position of which is known, to the target point to be surveyed are recorded as spatial standard data. Well-known modern examples of such geodetic surveying devices are tachymeters and total stations, which are also referred to as electronic tachymeter or computer tachymeter. For aiming at or targeting the target point to be surveyed, geodetic surveying devices of this type have, for example, a telescopic sight, for example, an optical telescope, as a targeting apparatus. The telescopic sight is generally rotatable about a vertical standing axis and about a horizontal tilt axis relative to a base of the measuring device, so that the telescope can be aligned on the point to be surveyed by pivoting and tilting. Modern devices can have, in addition to the optical vision channel, a camera, which is integrated in the telescopic sight and is aligned coaxially or in parallel, for example, for acquiring an image.

It is often the case that the target point, e.g. a boundary marker, cannot be directly targeted by the surveying device due to obstacles which interrupt the line of sight. Hence, points are surveyed in a number of geodetic applications by virtue of specially embodied target objects being placed thereon. According to the prior art, these consist of a rod as object support with a marking that can be targeted or with a retroreflector as target object. For surveying purposes, the tip of this plumb rod with the target point is brought into contact with the ground and held perpendicular to determine the direction. In so doing, in order to determine the distance, the rod will be aligned horizontally in such a way by rotating it about its vertical axis that the marking or the reflector reflects a light signal emitted by the surveying device back in the direction of the latter. Alternatively, use is made of 360° reflectors, which reflect light signals back from any horizontal alignment.

In order to enable geodetic surveying by a user on his own, some total stations according to the prior art have means for mechanizing the target optical unit, for automated target search and tracking and for remote control, as a result of which measurements can be performed by means of a suitable remote control unit from the target point. Modern total stations moreover contain microprocessors for digital further processing and storing of registered measurement data and a radio data interface for establishing a radio connection to external peripheral components such as e.g. a data-registering device attached to the surveying rod.

In many geodetic applications, points are surveyed by placing specially designed target objects thereon. These typically consist of a surveying rod having a targetable module, for example, a reflector for defining the measurement section or the measurement point. These target objects are targeted by means of a surveying device, a direction and a distance to the objects are determined, and a position of the objects is thus derived.

Similarly, to this point measurement, marking of already known target points or of points, the position of which was defined prior to a marking procedure, can be performed. In contrast to the point measurement, in this case, the position or the coordinates of the points to be marked are known and are to be marked. For such a marking procedure, a plumb stick or a surveying rod is conventionally also used, which rod is carried by a user and positioned on a target point. For this purpose, the user can move toward the target position of the target point based on position information generated by the surveying device, wherein the surveying rod is automatically targeted by the surveying device by a second person or by an automatic mechanism assigned to the surveying device. If the target point has been reached, the user can perform a marking of the point.

In general, a disadvantage of using such a plumb stick or surveying rod for geodetic or industrial surveying or stake-out in construction or manufacturing is that conveying and carrying a rod, which can be more than two meters long, is cumbersome to the user and particularly laborious in terrain that is difficult to pass, e.g. a wooded area. Moreover, perpendicular set up of the rod is connected to a certain amount of time expenditure and perpendicular holding during the measurement is arduous for the user. Incorrect setup of the rod at the target point is a source of error for an incorrect determination of position.

A further disadvantage is that target points could lie in such a way that perpendicular positioning of the rod on the target point is impossible or that it is even impossible to establish physical contact, e.g. if the target point is a corner of a building, if visual obstacles, e.g. bushes and trees, are present between the total station and the target object or if the surroundings of the target point cannot be entered by the user. Such situations require specific measurement methods, which are connected to additional time expenditure.

U.S. Pat. No. 6,381,006 B1 discloses a method and a corresponding device, by means of which surveying of inaccessible target points is possible. To this end, a plumb rod is equipped with at least two sensor elements, the absolute positions of which are determined by means of one or more reference stations, e.g. a geodetic surveying device. Furthermore, the plumb rod has a distance-measuring device, which measures the distance between distance-measuring device and a target point to be surveyed based on a visible measurement beam. The positions of the sensor elements and of the distance-measuring device relative to one another and the orientation of the distance-measuring direction are known. Hence, it is possible to calculate the absolute position of a target point from the measured distance and the measured absolute positions of the sensor elements.

However, the method according to the U.S. Pat. No. 6,381,006 B1 does not avoid the above-described disadvantages connected with the use of a plumb rod. Furthermore, it is disadvantageous that at least two sensor elements are required for determining the absolute position, which moreover must have a certain minimum distance between one another for sufficient resolution accuracy. As a result, the plumb rod becomes even more unwieldy. In addition, the alignment of the measurement beam (change of position and orientation of an alignment line) is purely manual by manual change of position of the surveying rod, e.g. by tilting the rod.

WO2019002554 A1 discloses a position enabled image projector or a surveying rod wherein position and orientation of the device with respect to all six degrees of freedom can be determined. The position is externally measured by a master device such as a total station and the orientation by sensors such as inclination sensors arranged at the device itself. This allows e.g. for an accurate projection of a blueprint on an object's surface or accurate measurements even if the surveying rod is not adjusted strictly vertical. However, according to the WO2019002554 A1, there is still the need of a tripod for placement of the image projector respectively of a rod for contacting and measuring a surveying point.

U.S. Pat. No. 5,903,235 discloses a geodetic surveying device that can be hand-held, with which surveying can be performed without use of a geodetic surveying device having a distance and direction measurement functionality and without use of a plumb rod or pole. Here, the target point to be surveyed is targeted by a pointing unit, e.g. a laser pointer. The position of the surveying device relative to the target point is established firstly by measuring the distance between device and target point in a defined direction by means of an integrated distance-measuring unit. In so doing, there is no need to align the device perpendicularly over the target point since a component which determines the inclination relative to the gravity vector is integrated. The absolute position of the surveying device is determined by a GNSS reception unit, as a result of which it is ultimately possible to calculate the absolute position of the target point due to the preceding measurements. Thus, handling of a plumb rod is dispensed with and it is possible to survey target points that could not be contacted physically by a plumb rod.

However, even when using correction signals, GNSS-based systems only enable a less accurate determination of the position of target points than systems based on the use of the distance and direction measurement functionality of a corresponding geodetic surveying device. Moreover, determining the position is bound to receiving a sufficient number of GNSS signals, which is not always the case, e.g. when tunneling or in narrow road lines. In addition, the emission direction of the laser pointer is fixed which makes correct pointing to a target point difficult or even impossible in some arrangements.

SUMMARY

In some embodiments, the present invention provides an enhanced device, which enables a system for surveying of target points to be measured and/or stake out of design points.

In some embodiments, the present invention provides a coordinate measuring and/or stake out device by means of which hardly accessible points can be measured resp. marked, with easy and convenient user handling for measuring and/or stake out tasks resp. with enhanced user support in measuring and/or stake out.

In some embodiments, the subject matter of the invention is a hand-holdable coordinate measuring and/or stake out device for hand-held, in particular one-handed, free carriage and movement/handling by a user, e.g. by a housing for hand-held usage. The device comprises a position giving means for determination of an actual translational position of the device using an external position reference, for example a GNSS-receiver or a measureable target such as a retroreflector serving as a target for an external measuring device such as a total station. The device further comprises an orientation giving means for determination of an actual rotational position of the device, e.g. an Inertial Measurement Unit (IMU). Due to the position and orientation giving means, the actual position of the device with respect to all six degrees of freedom (all rotational and translational DoF) of the device can be determined.

In some embodiments, the device further comprises a radiation source for generation of a radiation beam, particularly a laser beam, as measuring and/or marking beam for measuring and/or visually marking of an object point, and a beam steerer for automatic steering of an alignment of the beam, preferably with respect to at least two steering axis. Optionally, in case of measuring purpose, the device comprises a radiation detector or sensor for detection of parts of the radiation beam reflected back from an object (point) to be measured.

In some embodiments, the beam steerer comprises at least two beam steering operating modes which differ in the manner of automatic steering the beam alignment.

That means that the device has a beam steerer for aimed steering of an emission direction of the beam and for example a beam steerer controller designed to control the beam steerer in at least two automatic beam steering operation modes which allow for at least two different ways of automatic steering the beam.

Optionally, the beam steerer is designed to switch automatically between the two operating modes in dependence on sensor data, whereby preferably the sensor data provided by a sensor of the device, e.g. the orientation giving means. As a further option, the beam steerer is designed to adapt the automatically switching, in particular to a respective user, by machine learning.

In some embodiments, the at least two operating modes comprise a first and a second stabilization mode for stabilization of the beam alignment in order to compensate involuntary (unintentional) shifts of the housing, e.g. a shaking or jitter of the device, for example due to trembling of the user's hand holding the device or due to a shaky carrier. In the first stabilization mode, the beam alignment is strictly stabilized, whereas in the second stabilization mode, the beam alignment is semi-stabilized such that the beam follows a shift tendency.

The device according to this embodiment possesses two modes, each for automatic steadying of beam position, whereby the second stabilization mode is so to say “softer” and allows for a drift e.g. of the housing to be transformed in a change of the beam alignment whereas the first stabilization mode the beam position is more firmly stabilized. In the first stabilization mode, small but intentional movements of the device may be suppressed which would hinder manual fine-alignment of the beam. Thus, the second stabilization mode e.g. allows for an interruption of the strict stabilization mode, without losing beam stabilization in general or at all while enabling fine adjustment of the beam position.

An exemplary workflow using the advantage of the two stabilization mode could be as follows: first, the beam steerer is operated in the second stabilization mode which enables fine aiming at an object point, despite the point lying in the far field and despite jitter of the user's hand. Once the point is hit, the user manually or the device itself switches to the first stabilization mode wherefore the fine-aimed alignment is hold resp. even better guaranteed than in the second stabilization mode as shaking is more heavily equalized in the first stabilization mode.

In some embodiments, the beam steerer is designed to switch automatically between the first and the second stabilization mode in dependence on a sensed movement of the device, in particular switching is executed if the shift tendency is above or below a defined threshold and/or if a shift pattern is sensed. If for instance the amount and/or velocity of a sensed movement in a shift direction within a defined period of time reaches a certain value, the beam steerer controller automatically toggles the other stabilization mode.

In some embodiments, the at least two operating modes comprise a first and a second beam lock mode, wherein in the first lock mode the beam alignment relative to the housing is locked and in the second lock mode the beam is locked onto an object point. In other words, the first lock mode “freezes” the emission direction of the beam, the second lock mode binds the beam to an object point, despite movement of the device.

In some embodiments, one of the operating modes is a multi-point mode designed to steer the beam continuously in a direction (e.g. a straight line or a spiral or curve), in particular repeatedly and/or in form of a predefined pattern (e.g. a zig-zag-pattern), such that a multitude of neighbored object points is measured and/or marked, in particular in form of a dense point line or dense point area.

In some embodiments, one of the operating modes is an auto-align mode designed to automatically steer the beam to an object point of interest, in particular within a defined solid angle around an initial beam alignment, wherein the object point of interest is automatically detected by the device based on data of a device's sensor, for example a camera, and/or the beam is successively aligned such that a sequence of object points of interest is automatically measured and/or marked, for example the beam is steered from a first design point to the next design point in the vicinity of the first point.

In some embodiments, one of the operating modes is a graphic projection mode designed to automatically steer the beam in such a way that a visual graphic is projected by the beam onto an object's surface, preferably wherein the visual graphic is a user navigation information indicating a direction and/or distance to an object point to be measured and/or marked or a geographic direction, in particular north direction, or a direction and/or distance to the external position reference.

In some embodiments, the beam steerer comprises an active gimbal, wherein the gimbal is carrying or encasing the radiation source.

In some embodiments, the beam steerer comprises a micro scanning mirror and/or a scanning galvo (galvanometer) mirror and/or an array of movable mirrors.

In some embodiments, the beam steerer comprises at least one rotatable wedge prism.

In some embodiments, the device comprises an visual and/or audio display unit designed for user guidance with respect to beam steering. Alternatively or additionally, the device comprises a communication unit for transfer of such beam steering user guidance data to an external display device such as a total station or controller.

In some embodiments, the device comprises a separate or special user button which is conceived and reserved for manually switching between the at least two operating modes.

In some embodiments, the position giving means is embodied as a retroreflector or a GNSS-module.

In some embodiments, the orientation giving means is embodied as an Inertial Measurement Unit and/or tilt and heading sensors.

In some embodiments, the radiation source is part of an Electronic Distance Meter.

In some embodiments, the device is body-wearable.

In some embodiments, the invention also pertains to a surveying system comprising a surveying instrument, in particular a total station or a GNSS survey pole (surveying instrument with position determination by GNSS), and a coordinate measuring and/or stake out device according to the invention.

Optionally, the system comprises a computer (e.g., computer with processor and non-transient memory device having computer executable instructions) with an state estimator algorithm designed for computation of the actual position of the device, in particular wherein a distance measured with the radiation beam is fed into the state estimator for the position computation.

In some embodiments, the invention thus provides a coordinate measuring and/or stake out device with enhanced adaptability to different measurement and/or stake out situations due to its flexibility with respect to many degrees of handling freedom and the provision of two or more different operating modes. In addition, fulfilling tasks is simplified or even enabled in the first place in view of certain specific situations by the different beam steering operating modes.

The device according to the invention is user-friendly and unburdens the user in many respects such as search of target points, aiming at target points and keeping contact with a target point. In preferred embodiments with automatic switch instead of manual switch between operating modes, the effort for the user is even further reduced.

Additionally, the device enables measurement and/or stake out of points which cannot been satisfactorily treated with prior art devices and/or enhances precision of the results and/or reduces effort in time or means/measures.

Amongst others, the following problems are eliminated or at least reduced compared to nowadays standard methods: reduced effort because less need of making new total positioning system (TPS) setups, faster stake-out procedure using a beam-steered EDM, no effort in manually holding the handheld device quiet by using a beam steering element, measurements of remote points and/or points further away than the typical pole length (2 m) possible, no surveying pole needed and accordingly no pole height errors and no errors by mechanical bending of the pole as the distance to the target is measured with an EDM, no explicit north direction needed or otherwise manual alignment to a given coordinate system and having at least one hand free for marking while the handheld is projecting laser on design point (having two hands free in case of optional pole stand).

