Abstract: In an embodiment, a channel estimator includes first and second stages. The first stage is configurable to generate an observation scalar for a communication path of a communication channel, and the second stage is configurable to generate channel-estimation coefficients in response to the first observation scalar. For example, such a channel estimator may use a recursive algorithm, such as a VSSO Kalman algorithm, to estimate the response of a channel over which propagates an OFDM signal that suffers from ICI due to Doppler spread. Such a channel estimator may estimate the channel response more accurately, more efficiently, with a less-complex algorithm, and with less-complex software or circuitry, than conventional channel estimators. Furthermore, such a channel estimator may be able to dynamically account for changes in the number of communication paths that compose the channel, changes in the delays of these paths, and changes in the signal-energy levels of these paths.

Abstract: Examples of systems and methods are described for managing computing capacity by a provider of computing resources. The computing resources may include program execution capabilities, data storage or management capabilities, network bandwidth, etc. Multiple user programs can consume a single computing resource, and a single user program can consume multiple computing resources. Changes in usage and other environmental factors can require scaling of the computing resources to reduce or prevent a negative impact on performance. In some implementations, a fuzzy logic engine can be used to determine the appropriate adjustments to make to the computing resources associated with a program in order to keep a system metric within a desired operating range.

Abstract: Systems and methods are provided for generating a constraint-based, time-optimal motion profile for controlling the trajectory of a point-to-point move in a motion control system. A profile generator can calculate an ST-curve motion profile that includes a jerk reference that varies continuously over time for at least one of the motion profile segments, thereby producing a smooth, time-optimal trajectory. The profile generator can create the motion profile to conform to a set of motion constraints provided by the user. The profile generator also supports calculation of time-optimal motion profiles having segments that align to the sample time of the motion control system. In some embodiments, the profile generator can efficiently generate the motion profile by performing reference calculations only for those segments that will be used in the final motion profile for a given point-to-point move.

Abstract: A system that incorporates teachings of the subject disclosure may include, for example, a process that assigns a respective priority level to each of a number of tuning algorithms controlling different tunable elements of a communication device. A first tuning algorithm is executed according to a first priority level assigned to the first tuning algorithm. A remaining number of the tuning algorithms are executed to determine whether the first tuning algorithm has affected a tuning state of any of the remainder of tuning algorithms. A second of the number of tuning algorithms is executed in response to a stability condition of the first tuning algorithm and according to a second priority level assigned to the second tuning algorithm. Other embodiments are disclosed.

Abstract: A flow control valve includes a housing that includes a fluid inlet, a fluid outlet, a first work port and a second work port. The housing defines a spool bore and a pilot spool bore. A main stage spool is disposed in the spool bore. A pilot stage spool is disposed in the pilot spool bore. The pilot stage spool is in selective fluid communication with the main stage spool. A microprocessor includes a controller having a restricted structured controller and a compensation controller. Outputs of the restricted structured controller and the compensation controller are summed to form an electrical signal that is communicated to the pilot stage spool.

Abstract: Exemplary embodiments allow users to interactively formulate and solve multivariable feedback control problems. For example, users can solve problems where a plurality of control elements are distributed over one or more feedback loops and need to be jointly tuned to optimize overall performance and robustness of a control system. Embodiments allow users to specify design requirements and objectives in formats familiar to the user. Embodiments can operate on tunable parameters to solve the control problem in a manner that satisfies the design requirements and/or objectives provided by the user.

Abstract: A controller device and a method for controlling a system that utilizes an adaptive mechanism to self-learn the system characteristics and incorporates this adaptive self-learning ability to predict a control parameter correctly to provide precise control of a system component.

Abstract: A system for controlling a machine includes a first model, a second model, a controller, and a comparator. During a first cycle, the first model generates a response signal to the controller while the second model generates a predicted parameter signal. During the first cycle, the comparator transmits a feedback signal to the second model if a predetermined threshold is not met. A method for controlling a machine includes transmitting a response signal from a first model to a controller, generating a control signal to the machine, and generating a predicted parameter value in a second model. The method further includes transmitting a feedback signal to the second model if a predetermined threshold is not met.

Abstract: A system that incorporates teachings of the subject disclosure may include, for example, a method for detecting a plurality of use cases of a communication device, determining an initial tuning state for each of a plurality of tuning algorithms according to the plurality of use cases, configuring each of the plurality of tuning algorithms according to their respective initial tuning state, executing a first tuning algorithm of the plurality of tuning algorithms according to an order of execution of the plurality of tuning algorithms, detecting a stability condition of the first tuning algorithm, and executing a second tuning algorithm of the plurality of tuning algorithms responsive to the detected stability condition of the first tuning algorithm. Each tuning algorithms can control one of a tunable reactive element, a control interface, or both of one of a plurality of circuit components of a radio frequency circuit. Other embodiments are disclosed.

Abstract: A positioning control system for positioning a moving element on a basis of position command data is provided with a feedback loop. The system is also provided with a loop gain modifier for determining a loop gain, which is to be used in a following positioning operation, on a basis of a difference between an amount of overshoot measured in a current positioning operation and a predetermined tolerance or on a basis of a difference between an amount of overshoot measured in a current positioning operation and a first predetermined tolerance and a difference between an amount of undershoot measured in the current positioning operation and a second predetermined tolerance. The first and second tolerances may preferably be the same in absolute value. The moving element may specifically be a steerable mirror for drilling holes in a work by reflecting a laser beam. Also disclosed is a laser drilling machine including the system.

Abstract: In one implementation, an environmental controller operates a cooling system in an electronic device. The environmental controller includes a closed loop control system for operating a cooling fan at a target speed. The environmental controller may select the target speed based on one or more temperature sensors. The environmental controller may select the target speed based on the speeds of additional fans or the fans may be controlled in unison. The closed loop control system includes a proportional weight. When a measured cooling fan speed deviates from the target speed by more than a threshold error value, the proportional weight is constant. As the measured cooling fan speed approaches the target speed, and the threshold error value is crossed, the proportional weight is variable. The variance may be a function of time such as a periodic stair step function.

Abstract: A factory control server stores module configuration data for modules. The modules include processes for producing a final product and have corresponding module requirements. The factory control server analyzes in real-time actual product output data that is generated by a final product tester after a factory produces at least one final product to determine whether the actual product output data meets an expected product output. The factory control server analyzes actual module data in real-time to determine a new module requirement to cause new actual product output data for a subsequent final product to meet the expected product output in response to a determination that the actual product output data does not meet the expected product output. The factory control server notifies a module controller in real-time of the new module requirement. The module controller changes parameters in real-time to manufacture the subsequent final product.

Abstract: Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Abstract: Event prediction using hierarchical event features is described. In an embodiment a search engine monitors search results presented to users and whether users click on those search results. For example, features describing the search result events are universal resource locator prefix levels which are inherently hierarchically related. In an embodiment a graphical data structure is created and stored and used to represent the hierarchical relationships between features. An online training process is used in examples which enables knowledge to be propagated through the graphical data structure according to the hierarchical relations between features. In an example, the graphical data structure is used to predict whether a user will click on a search result and those predictions are used by the search engine to rank search results for future searches. In another example the events are advertisement impressions and the predictions are used by an online advertisement system.

Abstract: A system and method for controlling a plant having a minimum phase transfer function P(s) and given an input signal u, the plant having an output y and a plant frequency range comprising a transfer function J(s) comprising the product of a high gain filter J1(s) having a gain k1 sufficient that ? J ? ( ? ) ? > [ 1 + 1 ? ] when |?|??1 and |1+J(?)|>1/M for all ? wherein ?1 is selected to obtain a desired time response, and a low pass filter J2(s) selected such that |1+J(?)|>1/M for all ? and J(s) is strictly proper, wherein ?<1 and M>1 and ? and M are selected to meet a desired sensitivity requirement. An error signal e is calculated comprising the difference between the system input signal u and the plant output signal y, and the error signal modified according to the transfer function C(s)=P?1(s)J1(s)J2(s) and inputting the error signal into the plant. The system and method can be extended to unstable invertible plants.

Abstract: A control system for using a predictive control with a control process having a time delay includes an adaptive feedback controller and a predictor. The predictor uses at least an adaptively updated control parameter from the adaptive feedback controller to predict the output of the control process during the time delay. The control system further includes a filter that dampens the rate of change of the adaptively updated control parameter provided to the predictor from the adaptive feedback controller to slow the adaptation of the predictor relative to the adaptation of the adaptive feedback controller.

Abstract: An apparatus for tuning a parameter of a Kalman filter in a wheel inspection for a vehicle is disclosed. The apparatus includes an association module that associates wheel inspection data of the vehicle with locations of corresponding wheels in the vehicle; an evaluation module that evaluates a wheel stable score of the vehicle based on the wheel inspection data and the association, where the wheel stable score indicates reliability of the wheel inspection; and a parameter tuning module that tunes a measurement error covariance of the Kalman filter according to the evaluated wheel stable score.

Abstract: A variable impedance circuit is provided as an active load between an input line L1 and an output line L2. This circuit has low impedance with respect to a DC electric current signal and has high impedance with respect to an AC electric current signal, structured from a series circuit of resistors R1, R2, and R3 connected between lines L1 and L2; a transistor Q1 having the collector connected to the line L1 and the base connected between the resistors R2 and R3; a resistor R4 connected between the emitter of the transistor Q1 and the line L2; a capacitor C1 with one end connected between the resistors R2 and R3; a resistor R5 connected between the other end of the capacitor C1 and the line L2; a capacitor C2 having one end connected between the resistors R1 and R2; and a resistor R6 connected between the other end of the capacitor C2 and the line L2.

Abstract: A control system is described for controlling the operation of a target system, such as a data center. The control system uses a prediction module to predict demand for resources of the target system for future time steps. The control system then uses a transition determination module to determine state transitions within the target system to address the predicted demand. Each state transition describes a number of units to be advanced from a first state, at a first time step, to a second state, at a second time step. The control system then commences those state transitions which begin in the current step, and then repeats the predicting and determining for a next time step. The transition determination module can determine the state transitions by operating on an objective function that includes a demand difference component and a cost component, as subject to a set of conservation equations.

Abstract: A notch filter includes first, second, and third difference modules, a delay module, and a gain module. The first difference module calculates a first difference between a control signal in a pulse width modulation (PWM) system and a feedback value. The second difference module calculates a second difference between the first difference and a delayed second difference. The delay module generates the delayed second difference by introducing a one period delay to the second difference, wherein the period is based on a Nyquist frequency of the control signal. The gain module generates the feedback value by applying a gain to the delayed second difference. The third difference module generates a filtered control signal by calculating a difference between the signal and the feedback value, wherein the filtered control signal is used to control an operating parameter of the PWM system.

Abstract: A system for controlling start-up of a feedback controller includes a memory device and a processing circuit. The processing circuit is configured to receive a gain parameter from the feedback controller and to store the gain parameter in the memory device. The processing circuit is further configured to multiply the stored gain parameter and to cause the feedback controller to use the multiplied gain parameter in response to a determination that the feedback controller has restarted.

Abstract: The reduced complexity auto-tuning process controller system and method is a control scheme in which, for each process variable, a single gain K, which is initialized with a sufficiently small value, is iteratively auto-tuned using a predetermined discrete sample time and learning rate. A plant error is calculated and summed with an output of a one-sample delay, the sum being input to the one-sample delay. The combined output of the one-sample delay is multiplied by the input signal, i.e., used as a gain constant of the control input signal. The control input signal times this gain constant is fed to the plant input, thereby reducing error in the plant.

Abstract: In certain embodiments, a control system includes a model-less controller configured to control operation of a plant or process. The control system also includes an automation controller operatively connected for access to a model of the plant or process being controlled by the model-less controller. The automation controller is configured to modify parameters of the model-less controller via an explicit optimization procedure.

Abstract: An auto-compensation method for compensating power regulators configured to generate a regulated output voltage. Auto-compensation may be performed dynamically by determining various coefficients of a compensation function used in compensating the power regulator, based on assumptions about the structure of the regulator and corresponding filters. The method may be used to determine at least the DC loop gain and the position of the compensation zeros, without requiring any prior knowledge of the values of the various components of the system. Furthermore, the selection of the compensation parameters (loop gain, position of zeroes) may be based on measurement of various state variables of the actual power converter, and adjustment of the various coefficients of the compensation function according to the measurements. Since no power-plant model of the power regulator is used, inaccuracies that would be inherent using any method that employs a model of the system instead of the system itself may be eliminated.

Abstract: Controller scaling and parameterization are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also applies to state feedback and state observer based controllers, as well as linear active disturbance rejection controllers. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the application. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A method and apparatus for intelligently controlling continuous process variables. An automatic controller comprises an Intelligent Engine mechanism and a number of Model-Free Adaptive (MFA) controllers, each of which is suitable to control a process with specific behaviors. The Intelligent Engine can automatically select the appropriate MFA controller and its parameters so that the automatic controller can be easily used by people with limited control experience and those who do not have the time to commission, tune, and maintain automatic controllers.

Abstract: An autonomous floor cleaning robot includes a transport drive and control system arranged for autonomous movement of the robot over a floor for performing cleaning operations. The robot chassis carries a first cleaning zone comprising cleaning elements arranged to suction loose particulates up from the cleaning surface and a second cleaning zone comprising cleaning elements arraigned to apply a cleaning fluid onto the surface and to thereafter collect the cleaning fluid up from the surface after it has been used to clean the surface. The robot chassis carries a supply of cleaning fluid and a waste container for storing waste materials collected up from the cleaning surface.

Abstract: A method includes obtaining information identifying a predicted trajectory of material-based measurements associated with a transfer of material. The method also includes obtaining actual material-based measurements during the transfer of the material and determining whether the actual material-based measurements fall outside of the predicted trajectory. The method further includes identifying a problem with the transfer of the material if at least one of the actual material-based measurements falls outside of the predicted trajectory. The method may also include generating the predicted trajectory of the material-based measurements using historical data associated with one or more prior transfers, such as historical data associated with at least one pump to be used during the transfer of the material. The actual material-based measurements could include measurements of a level and/or a volume of the material in a tank.

Abstract: In some embodiments, a method of using feedforward to control a system component may include determining if a feedforward term exists in a feedforward table for a received operating set point. If a feedforward term does not exist, the system component may be incremented until the system is within a first acceptable tolerance of the desired set point. In some embodiments, a measure of steady state error may be determined and compared to a second acceptable tolerance. If within the acceptable tolerance, the corresponding feedforward term may be recorded in the feedforward table. In some embodiments, if the feedforward term exists for the operating set point, the system component may be controlled using controller output that corresponds to the feedforward term. When a change to the system is detected that is associated with possible changes to the feedforward values, new feedforward values may be generated for the feedforward table.

Abstract: There is described a method for determining a value of a zero point offset of a yaw rate sensor. The method comprises measuring over time the output of the yaw rate sensor, determining whether the measured output has remained within a set of limits for a pre-determined period and if it is determined that the measured output has remained within the limits for the pre-determined period, using at least one measured value of the output to determine the value of the zero point offset.

Abstract: The present application provides an adaptive control system for controlling a plant in particular a DC-DC power converter. The control system has two controllers of differing characteristics. The output of the individual controllers H0 and H1 are combined together to provide a combined control signal H to the plant, where H=?H1+(1??)H0 and where the adaptive control system is tuned by adjusting the value of ? between 0 and 1 to find an optimum control position.

Abstract: Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

Abstract: A method and system for updating tuning parameters associated with a controller without repetitive compilation of a controller code. The controller code represents an algorithm associated with the controller and can be compiled separately from a data set representing a solution for an optimization problem and also from a data set representing parameters required for prediction. The algorithm can be implemented in a programming language code suitable for implementation on an embedded platform or other types of computer platforms. The data sets can be represented in a specified data structure and the variables associated with the data structure can be declared in the controller template code. The variables can be updated independently without varying the compiled code associated with the controller algorithm that is referring to the variables. The controller can also be updated while the controller actively performs online.

Abstract: Exemplary embodiments allow users to interactively formulate and solve multivariable feedback control problems. For example, users can solve problems where a plurality of control elements are distributed over one or more feedback loops and need to be jointly tuned to optimize overall performance and robustness of a control system. Embodiments allow users to specify design requirements and objectives in formats familiar to the user. Embodiments can operate on tunable parameters to solve the control problem in a manner that satisfies the design requirements and/or objectives provided by the user.

Abstract: A system that incorporates teachings of the subject disclosure may include, for example, a method for detecting a plurality of use cases of a communication device, determining an initial tuning state for each of a plurality of tuning algorithms according to the plurality of use cases, configuring each of the plurality of tuning algorithms according to their respective initial tuning state, executing a first tuning algorithm of the plurality of tuning algorithms according to an order of execution of the plurality of tuning algorithms, detecting a stability condition of the first tuning algorithm, and executing a second tuning algorithm of the plurality of tuning algorithms responsive to the detected stability condition of the first tuning algorithm. Each tuning algorithms can control one of a tunable reactive element, a control interface, or both of one of a plurality of circuit components of a radio frequency circuit. Other embodiments are disclosed.

Abstract: Example methods and apparatus to predict process quality in a process control system are disclosed. A disclosed example method includes receiving process control information relating to a process at a first time including a first value associated with a first measured variable and a second value associated with a second measured variable, determining if a variation based on the received process control information associated with the process exceeds a threshold, if the variation exceeds the threshold, calculating a first contribution value based on a contribution of the first measured variable to the variation and a second contribution value based on a contribution of the second measured variable to the variation, determining at least one corrective action based on the first contribution value, the second contribution value, the first value, or the second value, and calculating a predicted process quality based on the at least one corrective action at a time after the first time.

Abstract: Controller scaling and parameterization are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also applies to state feedback and state observer based controllers, as well as linear active disturbance rejection controllers. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the application. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A control unit of a system stabilization device uses a fluctuation detection block (60) to determine fluctuation components included in the active component and reactive component currents of a system current and fluctuation components included in the frequency signal and the amplitude signal of a system voltage. The high frequency cut-off of the fluctuation detection block (60) is set to be f1; the low frequency cut-off is set to be f2. The fluctuation detection block (60) is composed of a low-pass filter (61) with a time constant of T1, a low-pass filter (62) with a time constant of T2, a subtracter (63) which outputs the difference, between the output signals of the filter (61) and the filter (62), and a feedback circuit (64) which provides feedback on the output of the subtracter (63) to the filters (61, 62). Thus, stability is ensured without using a current detector.

Abstract: A flow control valve includes a housing that includes a fluid inlet, a fluid outlet, a first work port and a second work port. The housing defines a spool bore and a pilot spool bore. A main stage spool is disposed in the spool bore. A pilot stage spool is disposed in the pilot spool bore. The pilot stage spool is in selective fluid communication with the main stage spool. A microprocessor includes a controller having a restricted structured controller and a compensation controller. Outputs of the restricted structured controller and the compensation controller are summed to form an electrical signal that is communicated to the pilot stage spool.

Abstract: Embodiments provide techniques, computer-readable media, and devices for allowing users to perform interactive design of controllers, such as PID controllers, in a free-form modeling environment. Users can tune controllers using characteristics familiar to typical users rather than having to specify gain values for the controller, which may be difficult for a user to relate to the performance of a controller.

Abstract: A test system can comprise a controller configured to provide a closed loop. The closed loop can comprise a forward transfer function with programmable coefficients that is configured to receive a signal corresponding to a command signal. The closed loop can also comprise a feedback transfer function having programmable coefficients and can be configured to provide a feedback signal that is subtracted from the command signal. The controller can be configured to provide a control signal corresponding to an output of the forward transfer function.

Abstract: A position control device for suppressing occurrence of stick-slip during a feed operation performed in a very low speed region is provided. Adders add an output obtained by multiplying actual speed deviation by a proportional gain, an integral component of actual speed deviation obtained by inputting actual speed deviation to an integral compensator, an output obtained by multiplying motor speed deviation by a proportional gain, and an integral component of the motor speed deviation obtained by inputting motor speed deviation to an integral compensator. The result is output as a torque feedback command. Each integral compensator has a coefficient changer capable of changing a coefficient from 0 to 1 to adjust integral gains in accordance with a speed feedforward command or a speed command. Large integral gain increases the response speed of switching from static to kinetic friction torque in a very low speed region thereby suppressing occurrence of stick-slip.

Abstract: Controller scaling and parameterization are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also applies to state feedback and state observer based controllers, as well as linear active disturbance rejection controllers. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the application. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: The control of flexible systems is often difficult due to the exact frequencies of the elastic modes being hard to identify. These flexible modes may change over time, or vary between units of the same system. The variation in the modal dynamics may cause a degradation in performance or even instabilities unless compensated for by the control scheme. Controllers designed for these types of systems use notch filters for mode suppression. However variation in the parameters of the flexible modes may cause the need for wide notch filters. An adaptive scheme is proposed which uses an online estimator based on plant parameterization. The scheme may not use probe signals and may not rely on exact parameter identification of the unknown parameters. Instead it may continuously update itself to cancel the effect of the flexible modes by been able to identify the effect of the modal dynamics on the performance of the system.

Abstract: Controller scaling and parameterization are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also applies to state feedback and state observer based controllers, as well as linear active disturbance rejection controllers. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the application. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A method for tuning operation of servo motors includes selecting a plurality of discrete positions in a guillotine blade cycle for which to determine tuning coefficients, determining tuning coefficients at the discrete positions, interpolating tuning coefficients for positions between the discrete positions, and applying the determined and the interpolated tuning coefficients to the servo motor. The servo motors may be used in connection with a guillotine cutter for separating individual sheets from a continuous web. The guillotine cutter blade may be driven by a servo motor to cyclically lower and raise to transversely cut the web transported below the cutter blade.

Abstract: Systems and methods for adaptive control are disclosed. The systems and methods can control uncertain dynamic systems. The control system can comprise a controller that employs a parameter dependent Riccati equation. The controller can produce a response that causes the state of the system to remain bounded. The control system can control both minimum phase and non-minimum phase systems. The control system can augment an existing, non-adaptive control design without modifying the gains employed in that design. The control system can also avoid the use of high gains in both the observer design and the adaptive control law.

Abstract: A method and device for controlling a process variable based upon a set point is disclosed. A process variable is measured, and a proportional term is assigned to a manipulated variable that is based upon a product of a proportional gain coefficient and an error magnitude between the process variable and the set point. An integral term is added to the manipulated variable under a first set of conditions, and a derivative term is added to the manipulated variable under a second set of conditions different from the first set of conditions. The sum of the proportional term, the integral term, and the derivative term is output, resulting in the process variable being responsively adjusted thereto.

Abstract: The frequency characteristic of a controller is acquired. The gain characteristic and phase characteristic of a controlled system are acquired. The open-loop transfer characteristic of the control system and the variation range of the open-loop transfer characteristic are computed from a variation range of the frequency characteristic of the controlled system and the frequency characteristic of the controller, and the variation range of the frequency characteristic of the controlled system is a region where a variation range of the gain characteristic and a variation range of the phase characteristic overlap in a complex coordinate system. The stability of the control system is estimated from the open-loop transfer characteristic and the variation range of the open-loop transfer characteristic.

Abstract: There is provided a digital controller which can reduce a variation in output voltage as compared to the conventional digital controller at the time of abrupt changes in load and in input of a power amplifier. The digital controller is built in the power amplifier for supplying an output voltage vo to a load and is equipped with a manipulated variable calculating unit which detects the output voltage vo to calculate a manipulated variable ?1 and a signal generating unit which converts the manipulated variable ?1 into a signal for making the power amplifier operate. A feedforward function from an equivalent disturbance qy caused by the variation in the load is replaced by a feedback function from the output voltage vo and the manipulated variable ?1, thereby allowing a transfer characteristic from the disturbance qy to the output voltage vo to result in a quadratic differential characteristic.