Method for calibrating a detection device, and detection device

Patent metadata

Field	Value
Publication number	US-10495456-B2
Application number	US-201414249666-A
Country	US
Kind code	B2
Filing date	Apr 10, 2014
Priority date	Apr 12, 2013
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

A device designed for the three-dimensional geometrical detection of an environment includes at least one inertial measurement system for provisionally calculating a trajectory of the detection device. The device is calibrated by steps of: (a) positioning and/or orienting the detection device in a position and/or orientation with respect to at least one reference point characterized by at least one predefined relative coordinate, or determining at least one relative coordinate which characterizes the position and/or the orientation of the detection device relative to at least one reference point; (b) determining at least one error variable which characterizes the deviation of the relative coordinate in accordance with step (a) from the relative coordinate(s) provisionally calculated by the inertial measurement system; and (c) if the error variable fulfills a predefined correction criterion, correcting the provisional trajectory.

First claim

We claim:

1. A method for calibrating a detection device comprising a laser scanner which is designed for three-dimensional geometrical detection of an environment and which comprises at least one inertial measurement system, the method comprises the following steps:
with the inertial measurement system, provisionally computationally determining a trajectory of the detection device by time-dependently determining a position and an orientation of the detection device relative to the environment,
positioning the detection device at multiple reference points, wherein each positioning of the detection device constitutes a point in time of rest, wherein each reference point is
(i) predefined and the detection device is positioned at the known reference point at the point in time of rest, or
(II) initially undefined but defined by a tachymeter and an on-board retroreflector determining a position of the detection device at the point in time of rest,

for each position provisionally computationally determined by the inertial measurement system at a point in time of rest, determining multiple error variables which in each case characterize a deviation of a position of a reference point from the respective provisionally computationally determined position; and
correcting the trajectory provisionally computationally determined by the inertial measurement system in such a way that each position of the detection device provisionally computationally determined at a point in time of rest is substituted by a position that corresponds to a reference point, for which the error variable is the smallest.

2. The method according to claim 1 , wherein a point in time of rest is determined either:
by the inertial measurement system at a point in time at which linear velocity and angular velocity of the detection device are either zero or at least below predefined threshold values, or
manually by a user via an interface comprised by the detection device if the user has brought the detection device to rest.

3. The method according to claim 1 , wherein for positioning at least one of the following steps is performed:
effecting a mechanical contact between a contact point of the detection device with a reference point,
directing a light beam emitted by the detection device onto a reference point, and
directing a camera at a reference point.

4. The method according to claim 1 , wherein at least one position of a reference point is determined optically, with aid of at least one laser distance measuring device.

5. The method according to claim 1 , wherein at least one absolute coordinate of a position of at least one reference point is known and is used when determining the error variable.

6. The method according to claim 1 , wherein at least one relative coordinate which characterizes the relative position of at least two reference points with respect to one another is known and is used when determining the error variable.

7. The method according to claim 1 , wherein at least three different reference points lie on a common reference line segment.

8. The method according to claim 7 , wherein at least one reference line segment is defined by a reference laser beam.

9. The method according to claim 8 , wherein the reference laser beam is detected with aid of a laser detector.

10. The method according to claim 1 , wherein a plurality of reference points He on a predefined trajectory, the detection device is moved along the predefined trajectory and the error variables are determined from the deviation of the trajectory provisionally computationally determined by the inertial measurement system from the predefined trajectory.

11. The method for calibrating a detection device according to claim 1 , wherein device calibration is independent of any global navigational signals, including GPS.

12. A detection device for three-dimensional geometrical detection of an environment, the detection device comprising:
a laser scanner,
t least one inertial measurement system configured for provisionally computationally determining a trajectory of the detection device by time-dependently determining position and orientation of the detection device relative to the environment, and a computer,
wherein the detection device is configured for being positioned at multiple reference points,
wherein each positioning of the detection device constitutes a point in time of rest, wherein each reference point is
(i) predefined and the detection device is positioned at the known reference point at the point in time of rest, or
(ii) initially undefined but defined by a tachymeter determining a position of the detection device at the point in time of rest, and

wherein the computer is configured for
for each position provisionally computationally determined by the inertial measurement system at a point in time of rest, determining multiple error variables which in each case characterize a deviation of a position of a reference point from the respective provisionally computationally determined position; and
correcting the trajectory provisionally computationally determined by the inertial measurement system in such a way that each position of the detection device provisionally computationally determined at a point in time of rest is substituted by a position that corresponds to a reference point, for which the error variable is the smallest.

13. The detection device according to claim 12 , wherein at least one of:
the inertial measurement system is configured for determining a point in time of rest at a point in time at which the linear velocity and the angular velocity of the detection device are either zero or at least below a predefined threshold value; and
the detection device comprises an interface for allowing a user to manually notify the detection device if said user has brought the detection device to rest.

14. The detection device according to claim 12 , wherein at least one of:
the detection device comprises a contact point configured for effecting a mechanical contact between the contact point and a reference point,
the detection device is configured for emitting a light beam for being directed onto a reference point, and
the detection device comprises a camera for being directed at a reference point.

15. The detection device for three-dimensional geometrical detection of an environment according to claim 12 , wherein device calibration is independent of any global navigational signals, including GPS.

16. A system comprising a detection device, for three-dimensional geometrical detection of an environment, and a tachymeter, the detection device comprising:
a laser scanner,
at least one inertial measurement system configured for provisionally computationally determining a trajectory of the detection device by time-dependently determining position and orientation of the detection device relative to the environment,
a retroreflector, and
a computer,
wherein the detection device is configured for being positioned at multiple reference points,
wherein each positioning of the detection device constitutes a point in time of rest. wherein each reference point is
(i) predefined and the detection device is positioned at the known reference point at the point in time of rest, or
(ii) initially undefined but defined by the tachymeter and the retroreflector determining a position of the detection device at the point in time of rest,

wherein the retroreflector is configured for rendering the position of the reference points determinable in interaction with the tachymeter by a light beam transmitted by the tachymeter and

Assignees

• p3d systems GmbH
• Leica Geosystems Ag

Inventors

• Vennegeerts Harald
• Hesse Christian
• Frei Erwin A

Classifications

• G01B21/16 Primary

  for measuring distance of clearance between spaced objects · CPC title

• G01C15/002

  Active optical surveying means (optical plumbing G01C15/105) · CPC title

• G01C25/00

  Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) · CPC title

• G01C7/00 Primary

  Tracing profiles (by photogrammetry or videogrammetry G01C11/00) · CPC title