Abstract: A self-configuring extremum-seeking controller includes a dither signal generator, a communications interface, a phase delay estimator, and a bandwidth estimator. The dither signal generator identifies a stored dither frequency, generates a dither signal having the stored dither frequency, and uses the dither signal to perturb a control input for a plant. The communications interface provides the perturbed control input to the plant and receives an output signal from the plant resulting from the perturbed control input. The phase delay estimator estimates a phase delay between the output signal and the dither signal. The bandwidth estimator estimates a bandwidth of the plant based on the estimated phase delay. The dither signal generator updates the stored dither frequency based on the estimated bandwidth.

Abstract: A cooperative extremum-seeking control system includes a first controller and a second controller. The first controller is configured to provide a first control input to a first plant and receive a first performance variable as feedback from the first plant. The second controller is configured to provide a second control input to a second plant that interacts with the first plant, receive a second performance variable as feedback from the second plant, and provide the second performance variable to the first controller. The first controller is further configured to aggregate the first performance variable and the second performance variable to determine a total performance variable, calculate a gradient of the total performance variable with respect to the first control input, generate a third control input using the gradient of the total performance variable, and provide the third control input to the first plant.

Abstract: A setpoint alarming system includes a feedback controller that monitors a process variable provided as a feedback signal from a plant and uses an error signal representing a difference between the process variable and a setpoint to generate a control signal for the plant. The plant uses the control signal to affect the process variable. The system includes a normalized index generator that uses the error signal to generate a normalized performance index for the plant. The system includes an expected value estimator that estimates a value of the normalized performance index expected to occur when a setpoint error of a predetermined magnitude has persisted for a predetermined duration. The system includes an alarm manager that compares the normalized performance index to the expected value and generates an alarm in response to the normalized performance index dropping below the expected value.

Abstract: Disclosed is a system to control a climate of a space via a first control loop and a second control loop interacting with the first control loop. The system includes a first controller of the first control loop to generate a first control signal based on a first modified set point and a first feedback signal. The system further includes a second controller of the second control loop to generate a second control signal based on a second modified set point and a second feedback signal. The system further includes a decoupler configured to predict a first effect of the first control signal on the second control loop and a second effect of the second control signal on the first control loop, and generate the first modified set point and the second modified set point to reduce the first effect and the second effect.

Abstract: A thermostat for transmitting data wirelessly to a controller in a building includes a temperature sensor, a processing circuit, and a wireless radio. The processing circuit is configured to receive a measured temperature value from the temperature sensor, determine a current temperature error based on the current measured temperature value and a setpoint temperature, and determine whether a difference between the current temperature error and a previous temperature error is greater than an error threshold. The processing circuit is configured to determine whether a minimum amount of time has passed since transmitting a previous measured temperature value and transmit the current measured temperature value to the controller via the wireless transmitter in response to determining that both the difference between the current temperature error and the previous temperature error is greater than the error threshold and the minimum amount of time has passed since transmitting a temperature value.

Abstract: An extremum-seeking control system includes a plant operable to affect a variable state or condition of a building and an extremum-seeking controller. The extremum-seeking controller is configured to provide a control input to a plant and receive a performance variable as a first feedback from the plant. The plant uses the control input to affect the performance variable. The extremum-seeking controller is configured to receive a constrained variable as a second feedback from the plant and calculate a performance penalty by applying a penalty function to the constrained variable. The extremum-seeking controller is further configured to modify the performance variable with the performance penalty to generate a modified cost function, estimate a gradient of the modified cost function with respect to the control input, and drive the gradient of the modified cost function toward zero by modulating the control input.

Abstract: A control system is configured to operate a multiple-input system to achieve an optimal value for a performance variable of the multiple-input system. The control system includes a mapper configured to generate a mapping from a first number of manipulated variables to a second number of latent variables. The second number is smaller than the first number and each of the latent variables includes a linear combination of the manipulated variables. The control system also includes an extremum-seeking controller configured to receive the performance variable from the multiple-input system as a feedback and modulate values of the second number of latent variables to drive the performance variable to the optimal value. The mapper is further configured to use the mapping to translate modulated values of the second number of latent variables to modulated values of the first number of manipulated variables and provide the modulated values of the first number of manipulated variables to the multiple-input system.

Abstract: A control system is configured to operate a plant to achieve an optimal value for a performance variable of the plant. The system comprise a feedforward controller configured to receive a measurable disturbance to the plant and generate a feedforward contribution to a control input to the plant using the measurable disturbance. The system also comprises an extremum-seeking controller configured to receive the performance variable from the plant and generate an extremum-seeking contribution to the control input to drive the performance variable to the optimal value. The system further comprises a control input element configured to generate the control input by combining the extremum-seeking contribution and the feedforward contribution and provide the control input to the plant.

Abstract: A controller includes a communications interface configured to provide a control input to and receive feedback from a plant. The feedback is representative of a response of the plant to the control input over a response period. The controller further includes a time constant estimator. The time constant estimator calculates a normalized variable based on the feedback, each value of the normalized variable representative of the response of the plant at a different time during the response period. The time constant estimator calculates a plurality of time constant estimates, based on the plurality of values of the normalized variable. The time constant estimator determines a maximum time constant from the time constant estimates. The controller further includes a control input generator that generates the control input for the plant using the maximum time constant. The control input affects a variable state or condition of the plant.

Abstract: A feedback controller for generating and using a normalized performance index for a feedback control loop is shown and described. The feedback controller is configured to generate an input for a control process, identify an error signal representing a difference between a setpoint and a feedback signal from the control process, compute a first exponentially-weighted moving average (EWMA) of a first function of the error signal and a second EWMA of a second function of the error signal, and to generate a normalized performance index using the first EWMA and the second EWMA.

Abstract: A method for controlling an economizer in a building HVAC system includes providing a manipulated variable as an input to a control process, holding the manipulated variable at a first extremum during a first portion of an evaluation period, and applying a dither signal to the manipulated variable during a second portion of the evaluation period. The dither signal causes the manipulated variable to deviate from the extremum. The method further includes monitoring a variable of interest output by the control process during the first and second portions of the evaluation period and switching the manipulated variable to a second extremum opposite the first extremum in response to the variable of interest moving toward an optimal value during the second portion of the evaluation period.

Abstract: A HVAC system for a building includes a plant and a plurality of single-variable extremum-seeking controllers (ESCs). The plant includes HVAC equipment operable to affect an environmental condition in the building. Each of the single-variable ESCs is configured to perturb a different manipulated variable with a different excitation signal and provide the manipulated variables as perturbed inputs to the plant. The plant uses multiple perturbed inputs to concurrently affect a performance variable. The single-variable ESCs are configured to estimate a gradient of the performance variable with respect to the each manipulated variable and independently drive the gradients toward zero by independently modulating the manipulated variables.

Abstract: An extremum-seeking control system for a chilled water plant includes a feedback controller and an extremum-seeking controller. The feedback controller is configured to operate equipment of the chilled water plant to achieve a condenser water temperature setpoint. The equipment include at least one of a chiller compressor, a condenser water pump, and a cooling tower fan. The extremum-seeking controller is configured to provide the condenser water temperature setpoint to the feedback controller.

Abstract: A self-configuring extremum-seeking controller includes a dither signal generator, a communications interface, a phase delay estimator, and a bandwidth estimator. The dither signal generator identifies a stored dither frequency, generates a dither signal having the stored dither frequency, and uses the dither signal to perturb a control input for a plant. The communications interface provides the perturbed control input to the plant and receives an output signal from the plant resulting from the perturbed control input. The phase delay estimator estimates a phase delay between the output signal and the dither signal. The bandwidth estimator estimates a bandwidth of the plant based on the estimated phase delay. The dither signal generator updates the stored dither frequency based on the estimated bandwidth.

Abstract: A control system for a plant includes a controller and a sensor. The controller is configured to estimate a response time of the plant and adjust a sampling rate based on the estimated response time. The response time is a parameter that characterizes a response of the plant to a disturbance. The sensor is configured to receive the adjusted sampling rate from the controller, collect samples of a measured variable from the plant at the adjusted sampling rate, and provide the samples of the measured variable to the controller.

Abstract: A control system for a plant includes a controller configured to detect a disturbance in the control system. In response to detecting the disturbance, the controller is configured to evaluate a signal affected by the disturbance to estimate a response time of a plant. The response time is a parameter that characterizes a response of the plant to the disturbance. The controller is configured to adjust an operating parameter used by the control system based on the estimated response time. The controller is configured to use the adjusted operating parameter to generate and provide an input to the plant.

Abstract: A method for adaptively and automatically adjusting a sampling rate in a feedback control system includes monitoring an error signal for a disturbance event, evaluating the error signal in response to the disturbance event to estimate a time constant of a control process, and determining a sampling rate for use in the feedback control system based on the estimated time constant. The error signal may be based on a difference between a setpoint and a feedback signal and the feedback signal may be received from the control process.

Abstract: A system for detecting a control loop interaction between two or more control loops. The system includes a processing circuit configured to store a history of detected loop disturbances for a plurality of control loops. The processing circuit is also configured to compute a measure of interaction between control loops using the history of detected loop disturbances. The processing circuit is further configured to determine whether a loop interaction exists based on the computed measure of interaction.

Abstract: A setpoint alarming system includes a feedback controller that monitors a process variable provided as a feedback signal from a plant and uses an error signal representing a difference between the process variable and a setpoint to generate a control signal for the plant. The plant uses the control signal to affect the process variable. The system includes a normalized index generator that uses the error signal to generate a normalized performance index for the plant. The system includes an expected value estimator that estimates a value of the normalized performance index expected to occur when a setpoint error of a predetermined magnitude has persisted for a predetermined duration. The system includes an alarm manager that compares the normalized performance index to the expected value and generates an alarm in response to the normalized performance index dropping below the expected value.

Abstract: A method for controlling an economizer in a building HVAC system includes providing a manipulated variable as an input to a control process, holding the manipulated variable at a first extremum during a first portion of an evaluation period, and applying a dither signal to the manipulated variable during a second portion of the evaluation period. The dither signal causes the manipulated variable to deviate from the extremum. The method further includes monitoring a variable of interest output by the control process during the first and second portions of the evaluation period and switching the manipulated variable to a second extremum opposite the first extremum in response to the variable of interest moving toward an optimal value during the second portion of the evaluation period.