Abstract: The positioning system of an industrial robot having a vision sensor and structured light pattern projector, such as a welding robot, is centered and vectored along a joint to be tracked. Navigation information derived from the scene is used to compute move microvectors; the next move vector is extracted and computed while the current move vector is executed. To track 90.degree. corners and small radius turns, the parallelism between two lines formed by the intersection of concentric circular arc light stripes and the joint edges is determined. When the parallelism is out of limits the previously calculated microvector is used until parallelism is re-established.

Abstract: A technique of determining the distribution of pulses along two perpendicular X-Y axes of a numerically controlled machine can be used for linear, circular, and parabolic interpolations and may be extended to computer graphics. At the initial point on the curve and at each succeeding point, a decision is made to increment the X axis, the Y axis, or both axes. This decision is based on a deviation index which is an index of closeness to the desired curve. Hardware is minimized and involves only additions, compares, shifts, and increments/decrements.

Abstract: A method for generating pulse width modulated (PWM) control signals from a reference waveform uses a unipolar timing waveform to modulate the reference waveform thereby avoiding the need for lock-out intervals to prevent shoot-through in power inverters supplied by the PWM control signals. Further, a sinusoidal reference waveform is approximated by a trapezoid, simplifying the computation of switching points located at intersections between the reference and timing waveforms.

Abstract: The surface of the molten weld pool and surrounding workpiece area are floodlighted during an arc welding operation by a narrowband light source such as a laser in order to highlight the pool boundary and yield an image which is easily computer processed to give the pool perimeter. An arc welding torch has built-in optical systems, one to route laser energy via a coherent optical fiber bundle to exit optics on the torch to project two spots of light onto the trailing side edges of the pool, another to image the weld region which is relayed to a remote camera. The difference between reflectance values and direction on the pool and workpiece surfaces accounts for the enhanced image.

Abstract: A two-valued height-based image of an object on a support surface is acquired in one frame time of a raster scan, television-like camera. Two rotating sheets of light projected by synchronized sources intersect at the supporting surface and form a moving light bar. The image of light bars incident on a 3D object is discontinuous because of the parallax effect. The light bar illuminates and sweeps out a rectangular area in step with the electronic scan of the scene imager.

Abstract: A versatile robotic gripper is easily and quickly adjusted to grip objects of different geometrical shapes without changing parts and under complete machine control. Opposing jaws have a matrix of axially movable pins each of which is mechanically locked in any axial position. Actuation of an operating mechanism to move the jaws together to grasp an object depresses the pins and they collectively conform to the shape of the object; the jaws retain this shape upon release of the object. A plate is raised to unlock the pins which are returned by springs to a fixed coplanar position.

Abstract: Laser processes such as cutting, drilling, and welding metals and other materials are performed manually with a hand held fiber optic laser tool. A near infrared or visible wavelength pulsed laser beam is coupled to the tool by a single clad quartz fiber whose ends are prepared to reduce losses and which transmits laser energy with peak powers in the kilowatt range to the output end. The hand held laser tool is comprised of focusing optics for the laser beam, an inert gas supply for welding cover gas, and an oxygen supply for gas assist cutting.

Abstract: Accurate estimates of the instantaneous mean frequency of a time varying signal are achieved at favorable and adverse signal-to-noise ratios by an improved time domain approach. Demodulated in-phase and quadrature signals are sampled and delayed. Noise in both terms of a simple arc tangent algorithm, whose denominator has products of time samples shifted at least one time period with respect to itself, is uncorrelated and removed by low pass filtering. One embodiment is a pulsed ultrasonic Doppler system with quadrature detection to measure and display blood velocity as a function of time.

Abstract: An industrial robot is controlled to move by increments and approximately track an edge or a joint. A structured light pattern such as two parallel light bars is projected onto the workpiece and the scene is imaged by a visual sensor. Information derived from the image is used to compute move vectors. The navigation algorithm is based on extracting and computing the next move vector from the visual scene while the current move vector is being executed. The positioning system of an arc welding robot approximately follows the joint to be welded; the computed microvectors specify the direction and distance the positioning system moves.

Abstract: A robotic welding system has a remote light pattern generator and a remotely located video camera and controller connected to an arc welding torch by flexible coherent fiber optic bundles. The improved torch has integral projection and viewing optical systems supported on the ring-shaped torch body. The first projects the light pattern onto the workpiece to measure workpiece profile and detect the joint location; the second produces an image of the weld puddle and light pattern for use as feedback information. The optical systems are tilted away from one another at a small angle corresponding to the angle of reflection to provide for optimum interception of the projected light pattern by the viewing optics.

Abstract: A compact gas tungsten arc welding torch, which may have an integral puddle view optical system, utilizes an inert gas supply line and coolant supply and return lines, one carrying current for the weld process. The torch body has passages for flow of cover gas from a connection tube to the gas nozzle. The gas supply hose additionally carries the filler wire for the weld process, which passes into the gas connection tube and out of the torch body to an integral wire feed guide tube that is alternatively inside or outside of the gas nozzle.

Abstract: A gas metal arc welding torch has an integral optical system which images the weld puddle on the face of a fiber optic cable. A concentric torch configuration is disclosed having a slim profile filler wire guide that is removably mounted on the ring-shaped torch body and projects into the gas cup at an angle to the optical axis to minimize obstruction of important regions of the weld scene. The fiber optic cable is coupled to a video camera and a viewing system or controller; real time observation of the weld area is made and used to control the weld process.

Abstract: A composite electrode configuration prevents mushrooming of resistance spot welding electrodes due to local high contact pressure and current densities. For a truncated electrode, an outer sleeve of high strength and high electrical resistivity material is attached to the end of the electrode and takes the high contact stress at the edge of the flat end face. A spherical end electrode has a plug of higher strength material in the center where the highest contact stress exists, and the outer sleeve reduces the joule heating effect. A transverse insulating spacer is a thermal and electrical barrier.

Abstract: The fidelity of limited-angle x-ray computerized tomography imaging is improved by taking multiple scans using x-ray beams at different energies. The projection data of the composite object is decomposed into the projections of the individual component substances. Reconstruction of a single substance is done more accurately than reconstructing the composite object because more a priori information about the object, such as upper and lower bounds of the densities of the substances, is available. The reconstructed images of the components are superimposed to form an image of the composite object. The method is applicable to other imaging modalities.

Abstract: Structured light patterns are introduced into the arc vicinity within the field of view of the integral optical sensor on a gas tungsten arc welding torch. Processing the image yields data needed to guide the torch and control and assess the weld process. The optical welding torch has a projector system with a remote light source and flexible fiber optic bundle over which the light pattern passes to an exit projection and relay assembly mounted on the torch. A programmable laser pattern projector, useful for other applications, has a beam deflection device that traces a two-dimensional pattern on the entrance of a coherent fiber optic bundle; no moving parts or electrical connections are needed at the terminal end. An optional modulator changes the pattern intensity spatially or temporally.

Abstract: The ballast temperature in the base up position of a miniature arc discharge lamp is reduced, increasing its lifetime, by placing a thin transparent thermal convection/radiation baffle between the arc tube and lamp filament, which are the heat source, and the interface of the envelope with the ballast housing. Greater temperature reduction is realized by putting insulation inside the housing cover and reducing the diameter of wires supporting the arc tube and filament, the latter a ballast resistor.

Abstract: An efficient power supply employs a high current switching transistor to pulse a flashlamp for optical pumping in lasers, such as an Nd:YAG laser at high pulse repetition frequencies. The pulsing circuit offers a simple, flexible, and precise means of pump pulse control. Flashlamp simmer current is provided from the constant dc voltage source with a resistor in parallel with the switching transistor.

Abstract: A gas tungsten arc welding torch has an integral optical system which images the weld puddle on the face of a fiber optic cable, and is suitable for industrial welding. The copper torch body has cover gas, electrical power, and coolant connections and an integral slim profile electrode holder. The optical lens is located directly above the electrode; the holder is out of focus and is not seen in the image of the weld region. A concentric torch configuration is more compact and has a large field of view at the weld area. When coupled to a remote video camera and monitor components, the torch-vision system permits control of torch manipulation and of the weld process.

Abstract: An instrumented spot welding electrode significantly improves the weld quality available from production resistance spot welding machines by providing real time measurements of key multivariable resistance welding parameters. The real time data provided may be used as inputs to adaptively control welding machines and dynamically adjust welding system operation responsive to the sensed variables. A number of sensors are positioned within a cavity specially formed into a water cooled electrode tip to obtain the desired measurements while being protected against physical damage. The sensors are advantageously placed in good thermal and electrical contact with a plug element which bears directly on the workpieces being welded to enhance the accuracy of the sensed variables. This specially configured and instrumented sensor cavity is ideally suited for use with all end types of electrodes including spherical, truncated, offset, flat and the like.

Abstract: A conventional ultrasonic B-scan image is converted into a volume backscatter image by accounting for four propagation effects: dispersion of transmitted energy, beam width and beam intensity variations, inhomogeneous attenuation of ultrasonic energy, and signals resulting from specular reflections at interfaces. These images are a two-dimensional map of backscatter efficiency, are independent of details of the measurement system, and are quantitative images of an intrinsic property of tissue and other materials.