Abstract: A brushless DC motor is controlled by determining a speed of the motor and a line voltage supplying drivers of the motor. Based upon these determined values and predetermined motor performance data, a maximum PWM on-time is determined for drive signals supplied to windings of the motor. This maximum PWM on-time thereby limits motor torque output to a predetermined maximum. Stopping the motor is performed in sequential phases including a loaded generator phase, an active braking phase and a holding phase. During holding, the amount of energy supplied to the motor is reduced to the point just before slippage such that holding energy is minimized. Upon power failure, the motor is driven toward a spring return home position overcoming static friction that may prevent the spring return mechanism from functioning properly. These techniques are applied to a motor in an actuator.

Abstract: A brushless DC motor is controlled by determining a speed of the motor and a line voltage supplying drivers of the motor. Based upon these determined values and predetermined motor performance data, a maximum PWM on-time is determined for drive signals supplied to windings of the motor. This maximum PWM on-time thereby limits motor torque output to a predetermined maximum. Stopping the motor is performed in sequential phases including a loaded generator phase, an active braking phase and a holding phase. During holding, the amount of energy supplied to the motor is reduced to the point just before slippage such that holding energy is minimized. Upon power failure, the motor is driven toward a spring return home position overcoming static friction that may prevent the spring return mechanism from functioning properly. These techniques are applied to a motor in an actuator.

Abstract: A planar array of electric conductors is stamped from a sheet of conductive material and has tabs for each of the conductors bent outwardly of the plane of the material. The conductors are interconnected by a plurality of webs and are affixed to a dielectric carrier sheet by an adhesive, whereupon the webs are severed and the conductors have electrical isolation. The carrier sheet and conductors are attached to a control panel and electric control devices are attached to the control panel over the conductors. The control devices are provided with terminals that extend in the same direction as the tabs of the conductors, and the control devices are electrically connected to the conductors by double ended push-on preformed connectors.

Abstract: An electronic selector knob circuit (10) which uses a tapped potentiometer (POT1) to provide accurate operation without requiring factory calibration. The potentiometer (POT1) is calibrated through on-board circuitry which includes a tap voltage biasing device and which monitors operation on a continual basis through both a current monitor (16) and a voltage monitor (18). A redundant disable circuit (14) provides a redundant hardware means for shutting off all oven heating elements.

Abstract: A multi-wavelength optical filter for a portabe gas analyzer includes a filter assembly having a first opening and multiple additional openings. The first opening has a linearly variable filter disposed therein, while the additional openings have discrete filters disposed therein. The filters are linearly aligned, such that filter selection is facilitated by using the filter assembly with a linear positioning mechanism.

Abstract: A wet scrubber control system is configured with a pH sensor and a conductivity sensor in the return solution, and with a conductivity sensor in the feed solution. Concentration of the scrubbing agent within the feed solution is determined using the conductivity of the feed solution, corrected by subtracting a bias therefrom. The bias is established by first measuring the concentration of scrubbing agent in the return solution using the pH sensor. An expected conductivity of the return solution is then looked-up. The bias is set as the difference between the expected conductivity of the return solution and a measured conductivity of the return solution.

Abstract: A power conditioning circuit for use in a power supply includes a power input and a power output. The circuit also includes a series connected RFI-EMI filter, rectifier, and SCR between the power input and the power output. The SCR has a control input for switching the SCR on and off, thereby interrupting current flow between the power input and the power output. An energy storage circuit is connected across the power output. Furthermore, the circuit includes a control circuit coupled to the control input of the SCR for switching the SCR on and off to maintain a regulated voltage at said power output in response to an AC input. A conditioned DC output is produced in response to a DC input.

Abstract: A method and apparatus for training and optimizing a neural network for use in controlling multivariable nonlinear processes. The neural network can be used as a controller generating manipulated variables for directly controlling the process or as part of a controller structure generating predicted process outputs. The neural network is trained and optimized off-line with historical values of the process inputs, outputs, and their rates of change. The determination of the manipulated variables or the predicted process outputs are based on an optimum prediction time which represents the effective response time of the process output to the setpoint such that the greatest change to the process output occurs as a result of a small change made to its paired manipulated variable.

Abstract: A polycrystalline pressure sensor is formed by depositing polycrystalline silicon piezoresistors on a polycrystalline sensing diaphragm. The piezoresistors are arranged in a wheatstone bridge configuration. During operation, an alternating differential signal is applied across the input of the wheatstone bridge. A measured voltage difference between the output terminals of the wheatstone bridge is used to detect imbalance in the electrical piezoresistors that corresponds to pressure applied to the sensor. Pressure is thereby measured.

Abstract: A method and apparatus providing an automated means for detecting unsoldered thru-hole connector leads is herein disclosed. This means consists of a thru-hole connection pad and a test pad positioned in close proximity to each lead of an electrical component. A thru-hole connection pad is formed about the periphery of each thru-hole. It serves to form a solder pad for securing the lead to the printed circuit board and establishes an electrical connection between the component and reverse sides of the printed circuit board. A test etch easily accessible by an automated testing device is positioned within close proximity of each thru-hole connection pad. As each lead is individually soldered to the printed circuit board, a solder bridge must also be formed across the thru-hole connection pad and the test etch thereby establishing an electrical connection between the lead and the test etch. This electrical connection is used by an automated testing device to detect any unsoldered leads.

Abstract: An apparatus and method for automatically adjusting the control parameters of a self-tuning controller used to regulate a process having a measured process variable signal. Using the measured process variable signal, an error signal representing a closed-loop response of the process to an upset condition is generated. Local extrema of the error signal is measured and three successive amplitude values are selected to produce measured decay and overshoot characteristics of the error signal. The three successive amplitude values are selected such that the measured decay characteristic is greater than the overshoot characteristic. Based on the measured decay and overshoot characteristics at least one of the control parameters of the controller is automatically adjusted to improve the difference between one of the measured characteristics and a target characteristic.

Abstract: A dual sensor vortex flow meter providing fluid connections for two sensors and containing isolation valves providing the further capability of separate valve control of the fluid communication to each of the dual sensors is herein disclosed. The vortex flow meter is mounted onto a flow meter body having an existing sensor cavity for housing a single sensor. The vortex flow meter is fitted into the existing sensor cavity by means of a dummy-cast sensor. On either side of the dummy sensor are apertures coupled to flow passages that transmit the alternating differential pressure fluctuations caused by the vortices from each side of the dummy sensor to the corresponding sides of each of the dual sensors. The dual sensor vortex flow meter may also include valves for controlling the process flow transmission to each of the sensors.

Abstract: A method and apparatus for increasing the resolution and accuracy of flow measurements made by vortex flowmeters through the use of an adaptive filter. A vortex sensor signal is conditioned by a bandpass filter whose corner frequencies are dynamically altered as a function of the measured frequency of the vortex sensor signal. When the change in frequency is relatively small, the filters' corner frequencies are set to track the frequency signal in accordance with a specified bandwidth thereby improving the signal-to-noise ratio. For large frequency changes, a new frequency signal is searched for thereby avoiding tracking erroneous noise signals. Furthermore, compensation for additional or missed vortex pulses is made thereby generating a more accurate vortex frequency measurement.

Abstract: An analog isolation circuit for providing electrical isolation between interrelated electrical circuitry contained within a vortex flowmeter. The circuit provides a low power and low cost solution to the problem of ground isolation presented in flowmeters utilizing grounded sensors which generate low frequency sinusoidal signals. A pair of clock-controlled analog switches couples the voltage difference between two successive samples of an analog signal across an isolation barrier. The operation of the switches at a low frequency rate and with a short sampling interval while utilizing a low magnetizing current preserves the magnitude of the input waveform while consuming approximately 1 mW of power.

Abstract: A method and apparatus for a robust process control system that utilizes a neural-network multivariable inner-loop PD controller cascaded with decoupled outer-loop controllers with integral action, the combination providing a multivariable nonlinear PID and feedforward controller. The inner-loop neural-network controller is trained to achieve optimal performance behavior when future process behavior repeats the training experience. The outer-loop controllers compensate for process changes, unmeasured disturbances, and modeling errors. In the first and second embodiments, the neural network is used as an inner-loop controller in a process control system having a constraint management scheme which prevents integral windup by controlling the action of the outer-loop controllers when limiting is detected in the associated manipulated-variable control path.

Abstract: A method and apparatus for a robust process control system which utilizes a neural-network based multivariable inner-loop PD controller cascaded with decoupled outer-loop controllers with integral action, the combination providing a multivariable nonlinear PID and feedforward controller. The inner-loop PD controller employs a quasi-Newton iterative feedback loop structure whereby the manipulated variables are computed in an iterative fashion as a function of the difference between the inner loop setpoint and the predicted controlled variable as advanced by the optimum prediction time, in order to incorporate the downstream limiting effects on the non-limited control loops. The outer-loop controllers compensate for unmodeled process changes, unmeasured disturbances, and modeling errors by adjusting the inner-loop target values.

Abstract: Multivariable adaptive feedforward control may be accomplished by detecting the beginning and ending of a process control disturbance response, characterizing the measured inputs and process output during the disturbance by moments, which comprise time-weighted integrals performed on the process result output and inputs when the disturbance is a measured disturbance, and relating the characterized inputs and process result output in known general transfer function model equations to generate transfer function parameters which are used to calculate the coefficients of feedforward additive or multiplicative compensators.