Kinematically positioned data acquisition apparatus and method

• US 5,440,492 A
• Filed: 12/23/1992
• Issued: 08/08/1995
• Est. Priority Date: 12/23/1992
• Status: Expired due to Fees

• Current Assignee: Charles M. Donoghue, Ghassan F. Kozah
• Original Assignee: Charles M. Donoghue, Ghassan F. Kozah
• Inventors: Donoghue, Charles M., Kozah, Ghassan F.
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/996,078
• Time in Patent Office: 958 Days
• Field of Search: 364/453, 364/454, 364/505, 364/559, 364/560, 364/561, 364/474.36, 364/474.37, 364/451, 364/460, 33/1 CC, 33/503, 33/504, 73/382 R, 73/382 G
• US Class Current: 701/221
• CPC Class Codes: G01B 7/004 for measuring coordinates of points

Abstract

An apparatus and method for measuring the location of points in a defined reference frame. The apparatus includes a plurality of linear and angular accelerometers that facilitate kinematic navigation as the device moves about in space. Thus, measurements may be taken from any orientation and location. In a first embodiment of the apparatus, a distance measuring device measures the distance to the point along a measuring axis and then calculates the location of the point in the defined reference frame based upon the distance to the point and the location and orientation of the device. In a second embodiment of the apparatus, a user touches the measured point with a touching member that aligns with the measuring axis. A computing device then calculates the location of the point based upon the location of the touching member and the location and orientation of the device. Data transfer port facilitates the transfer of data acquired by the device to other systems for immediate further use or display. Also included with the invention are features for aligning the axes of the defined reference frame with the earth'"'"'s local gravitational and north directions. The establishment of these references along with further associated steps facilitates the correction of positional errors.

Claims

1. A kinematically or semi-kinematically positioned data acquisition apparatus for measuring the physical location of a point on an object or space in a local reference frame, the apparatus comprising:

(a) a measuring means for determining the location of the point along a measuring axis;

(b) an inertial measurement means connected to the measuring means for continually providing data on the relative change in position and orientation of the measuring means;

(c) computing means for computing the location and orientation of the measuring means in a local reference frame in real-time based upon readings from the inertial measurement means and for calculating the coordinates of the measured point;

(d) gravity vector detection means for detecting the direction of the earth'"'"'s gravitational field and providing the direction of the earth'"'"'s gravitational field to the computing means;

(e) north direction detection means for detecting the direction of north and providing the direction of north to the computing means;

(f) error correcting means for correcting positional errors caused by drift in the inertial measurement means by using the earth'"'"'s gravitational field and the direction of north as reference directions; and

(g) data transfer means for transferring data between the measuring means, inertial measurement means, the computing means and a data port.

2. The apparatus of claim 1, wherein the measuring means includes:

(a) a distance measuring device that measures the distance from the measuring device to the measured point along the measuring axis.

3. The apparatus of claim 1, wherein the measuring means further comprises:

(a) touching means that aligns on the measuring axis for touching the measured point.

4. A method for measuring the location of a point in a local reference frame, the method comprising the steps of:

(a) establishing a local right-handed cartesian reference frame such that one axis is oriented parallel to a local north vector and one axis is parallel to a local gravity vector;

(b) aligning a measuring device so that a measuring axis aligns with the point;

(c) measuring the location of the point along the measuring axis relative to the measuring device;

(d) calculating the location and orientation of the measuring device in the local reference frame using data from an inertial measurement device that continually relates the relative change in position and orientation of the measuring means;

(e) calculating the coordinates of the point in the local reference frame using data on the location and orientation of the measuring means in the local reference frame and also the location of the point along the measuring axis with respect to the measuring means; and

(f) outputting the coordinates of the point in the local reference frame.

5. The method of claim 4 wherein the step of measuring the location of the point along the measuring axis relative to the measuring device includes:

(a) measuring the distance to the point from the measuring device along the measuring axis.

6. The method of claim 4 wherein the step of measuring the location of the point along the measuring axis relative to the measuring device includes:

(a) touching the point with a touching means that aligns on the measuring axis.

7. The method of claim 4, further comprising the steps of:

(a) establishing a user defined reference frame;

(b) calculating the coordinates of the measured point in the user defined reference frame; and

(c) outputting the coordinates of the point in the user defined reference frame.

8. The method of claim 4 further comprising the step of:

(a) correcting positional errors by placing the measuring device in a known location and orientation.

9. The method of claim 7 further comprising the step of:

(a) correcting positional errors by remeasuring the location of the point.