Abstract: An earthmoving system including a bulldozer has a pair of GPS receivers mounted on the cutting blade of the bulldozer. The cutting blade is supported by a blade support extending from the frame. The blade support includes a pair of hydraulic cylinders for raising and lowering the blade in relation to the frame and a blade tilt cylinder for controlling the lateral tilt of the cutting blade. Sensors, including gyroscopic sensors and an accelerometer, sense rotation of the frame about three orthogonal axes and vertical movement of the bulldozer frame that would affect the position of the blade. A control is responsive to the pair of GPS receivers and to the gyroscopic sensors, for controlling the operation of the hydraulic cylinders and thereby the position of the cutting blade.

Abstract: An earthmoving system including a bulldozer has a pair of GPS receivers mounted on the cutting blade of the bulldozer. The cutting blade is supported by a blade support extending from the frame. The blade support includes a pair of hydraulic cylinders for raising and lowering the blade in relation to the frame and a blade tilt cylinder for controlling the lateral tilt of the cutting blade. Sensors, including gyroscopic sensors and an accelerometer, sense rotation of the frame about three orthogonal axes and vertical movement of the bulldozer frame that would affect the position of the blade. A control is responsive to the pair of GPS receivers and to the gyroscopic sensors, for controlling the operation of the hydraulic cylinders and thereby the position of the cutting blade.

Abstract: A system and a method sense the inclination of a machine element, such as a platform, and eliminate tangential and radial acceleration errors. The platform defines orthogonal X and Y axes, and is rotatable about a Z axis. An inclinometer, mounted on the platform at a location spaced from the axis of rotation by a distance r, provides inclinometer outputs indicating acceleration in the X and Y directions, Ix and Iy, respectively. A rate gyro on the platform senses the rotational speed w of the platform. The rate gyro output w is differentiated and multiplied by r to determined tangential acceleration at the inclinometer. A circuit resolves the tangential acceleration into X axis and Y axis components, which are used to correct the inclinometer outputs Ix and Iy for errors that would otherwise result from tangential acceleration.

Abstract: The present invention includes a system and a method by which the inclination of a machine element, such as a platform, may be sensed, and errors that might otherwise result from tangential and radial acceleration eliminated. The platform defines orthogonal X and Y axes, and a Z axis orthogonal to both the X and Y axes. The platform is rotatable about an axis extending parallel to the Z axis. The system includes an inclinometer, mounted on the platform at a location spaced from the axis of rotation by a distance r, for providing inclinometer outputs indicating acceleration in the X and Y directions, designated as Ix and Iy, respectively. A line from the axis of rotation to the inclinometer forms an included angle B with the X axis. A rate gyro is mounted on the platform. The rate gyro senses the rotational speed w of the platform about the axis of rotation and provides a rate gyro output indicating the rotational speed w.

Abstract: A device and method detect a moving, relatively thin beam of laser light, and distinguishing between illumination of photodetectors by the beam, and illumination of the photodetectors by an omnidirectional pulse of light. A plurality of photodetector arrays are arranged in a generally vertical row, with each array having a generally vertical row of photodetector elements. Weighting circuits associated with the arrays provide first and second reference signals for each array related to the elements illuminated in the array. The ratio of sum of the reference signals to the difference between the largest and smallest of the reference signals is determined and interpreted as indicating illumination by a relatively thin beam of laser light when the ratio is less than a predetermined level, and as indicating illumination by an omnidirectional pulse of light when the ration is greater than the predetermined level.

Abstract: A laser beam receiver with non-interdigitated photosensors arranged in a repeating pattern of “n” channels of photosensors in each of “m” sectors is disclosed. The photocurrent from both the anode and cathode terminals of the photosensor is used to determine laser beam position. The repeating patterns connect one set of “n” channel amplifier channels with the corresponding set of “m” sector amplifier channels. The position of the laser beam is determined by its position relative to the sector and channel the laser beam impinges on. The laser beam position relative to sector boundaries is determined by the distribution of photosensor current into the “n” channels of amplifiers from the “n” photosensors within each sector. The sector of the photosensor the laser beam impinges on is determined by the distribution of photosensor current into the “m” channels of sector amplifiers from the “m” groups of “n” photosensors.

Abstract: A device and method detect a moving, relatively thin beam of laser light, and distinguishing between illumination of photodetectors by the beam, and illumination of the photodetectors by an omnidirectional pulse of light. A plurality of photodetector arrays are arranged in a generally vertical row, with each array having a generally vertical row of photodetector elements. Weighting circuits associated with the arrays provide first and second reference signals for each array related to the elements illuminated in the array. The ratio of sum of the reference signals to the difference between the largest and smallest of the reference signals is determined and interpreted as indicating illumination by a relatively thin beam of laser light when the ratio is less than a predetermined level, and as indicating illumination by an omnidirectional pulse of light when the ratio is greater than the predetermined level.

Abstract: A laser beam receiver with non-interdigitated photosensors arranged in a repeating pattern of “n” channels of photosensors in each of “m” sectors is disclosed. The photocurrent from both the anode and cathode terminals of the photosensor is used to determine laser beam position. The repeating patterns connect one set of “n” channel amplifier channels with the corresponding set of “m” sector amplifier channels. The position of the laser beam is determined by its position relative to the sector and channel the laser beam impinges on. The laser beam position relative to sector boundaries is determined by the distribution of photosensor current into the “n” channels of amplifiers from the “n” photosensors within each sector. The sector of the photosensor the laser beam impinges on is determined by the distribution of photosensor current into the “m” channels of sector amplifiers from the “m” groups of “n” photosensors.

Abstract: A device for detecting the relative position of a generally horizontal reference plane of light includes a plurality of photodetector elements, a weighting circuit, and an output circuit. The photodetector elements are positioned on the device in a generally vertically oriented row. The weighting circuit provides a portion of the electrical output of each photodetector element as a first reference signal related to the spacing of the photodetector element from a first end of said row, and a portion of the electrical output of each photodetector element as a second reference signal related to the spacing of the photodetector element from the second end of said row. The output circuit is responsive to the weighting circuit for determining the relative levels of the first and second reference signals and the position of said reference plane of light with respect to the detector device.

Abstract: A laser level with a sensorless DC motor controller having a feedback sampling circuit connected in parallel with the coil to sense back EMF. An integrator provides a feedback signal from the sensed back EMF, which the amplified difference from a reference level is used as a pulse width control signal. A pulse width modulation generator uses the control signal to generate variable “on” time pulse widths for each motor drive pulse such that high resolution is provided to the DC motor, permitting accurate rotor position at low rotational speeds. It is emphasized that this abstract is provided to comply with the rules requiring an abstract to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A laser level with a sensorless DC motor controller having a feedback sampling circuit connected in parallel with the coil to sense back EMF. An integrator provides a feedback signal from the sensed back EMF, which the amplified difference from a reference level is used as a pulse width control signal. A pulse width modulation generator uses the control signal to generate variable “on” time pulse widths for each motor drive pulse such that high resolution is provided to the DC motor, permitting accurate rotor position at low rotational speeds. It is emphasized that this abstract is provided to comply with the rules requiring an abstract to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A laser level with a sensorless DC motor controller having a feedback sampling circuit connected in parallel with the coil to sense back EMF. An integrator provides a feedback signal from the sensed back EMF, which the amplified difference from a reference level is used as a pulse width control signal. A pulse width modulation generator uses the control signal to generate variable “on” time pulse widths for each motor drive pulse such that high resolution is provided to the DC motor, permitting accurate rotor position at low rotational speeds. It is emphasized that this abstract is provided to comply with the rules requiring an abstract to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A device for detecting the relative position of a generally horizontal reference plane of light includes a plurality of photodetector elements, a weighting circuit, and an output circuit. The photodetector elements are positioned on the device in a generally vertically oriented row. The weighting circuit provides a portion of the electrical output of each photodetector element as a first reference signal related to the spacing of the photodetector element from a first end of said row, and a portion of the electrical output of each photodetector element as a second reference signal related to the spacing of the photodetector element from the second end of said row. The output circuit is responsive to the weighting circuit for determining the relative levels of the first and second reference signals and the position of said reference plane of light with respect to the detector device.

Abstract: A laser transmitter is provided including a specialized compensator assembly damping mechanism. In accordance with one embodiment of the present invention, a compensator assembly position detector is arranged to detect a position X1 of the compensator assembly with respect to the X-axis, and a position Y1 of the compensator assembly with respect to the Y-axis. The compensator assembly damping mechanism includes an X-axis magnetic damping mechanism, a Y-axis magnetic damping mechanism, and a rotational damping mechanism. The active feedback circuit is arranged to (i) drive the X-axis magnetic damping mechanism so as to increase a damping force generated by the X-axis magnetic damping mechanism as a rate of change of the signal indicative of the position x1 increases, and (ii) drive the Y-axis magnetic damping mechanism so as to increase a damping force generated by the Y-axis magnetic damping mechanism as a rate of change of the signal indicative of the position y1 increases.

Abstract: An autofocusing system for a laser transmitter is provided. A laser beam is swept across a target having a plurality of sections. The target includes a first reflective section and a second reflective section with a non-reflective section positioned therebetween. A photodetector detects a signal representative of the laser beam reflected from the target. The laser beam is focused by adjusting the focusing lens until a ratio of the duration of the non-reflective portion of the signal to the sum of the durations of the reflective portions of the signal is maximized.

Abstract: A system for adjusting the orientation of a plane defined by a rotating laser beam from a laser transmitter is provided. The laser beam is swept across one or more targets having a plurality of sections. The targets each include a first reflective section and a second reflective section with a non-reflective section positioned therebetween. The non-reflective section includes a portion which slopes across the reflective sections. A photodetector detects a signal representative of the laser beam reflected from each of the targets. The orientation of the laser beam is adjusted until the laser beam traverses the center of the target at which point the width of the first reflective section equals the width of the second reflective section. A processor calculates the distance or angle in which to adjust the laser transmitter so that the laser beam traverses the center of the target once the laser beam traverses the portion of the target including the sloped non-reflective section.