Abstract: Systems and methods for detecting the onset of wheel skids and controlling brake torque to achieve efficient and smooth braking performance are described herein. A brake control system may utilize an algorithm, along with substantially real-time measured values to assist with controlling brake torque to achieve efficient and smooth braking performance. A history of wheel speed information, such as wheel speed information associated with one or more landing event, may also be used to iteratively estimate tire/runway friction properties.

Abstract: An electronic controller device for automatic control of a heating, ventilating, air conditioning or refrigeration (HVAC&R) system has a digital recycle counter that is capable of intercepting a thermostat command for cooling, refrigeration, or heating and replacing the thermostat command with a modulated binary signal that operates in an “on” state or “off” state, and a computer-readable storage medium that comprises a program that includes an auto-configuration mode that is capable of determining a base line performance of the HVAC&R system through a commissioning phase and is capable of determining an adjusted performance based on energy consumption, temperature regulation, humidity regulation, or power limit or any combination thereof. The program can adjust the digital recycle counter “on” and “off” states based on the adjusted performance determination to reduce energy consumption.

Abstract: Sensing, actuation of apparatus, and a control algorithm for use in automatically controlling an air-conditioning system by sensing multiple conditions and responding by actuating the mechanical components of the air-conditioning system to optimize the temperature of the coolant fluid, provide improved zone temperature control, provide status of system components, and provide an alert if there is overheating of a supply side system mechanical component.

Abstract: Sensing, actuation of apparatus, and a control algorithm for use in automatically controlling an air-conditioning system by sensing multiple conditions and responding by actuating the mechanical components of the air-conditioning system to optimize the temperature of the coolant fluid, provide improved zone temperature control, provide status of system components, and provide an alert if there is overheating of a supply side system mechanical component.

Abstract: A method to determine and apply PI gain constants to an HVAC PI controller used to control an HVAC component includes the steps of: recording an opened loop HVAC component dynamic step response; fitting the HVAC component dynamic response to a transfer function model; calculating the PI gain constants from the model; entering the calculated PI gains into a PI control algorithm; and running the PI control algorithm on the HVAC PI controller to control the HVAC component. The inventive method can be used with an HVAC system comprising, an HVAC system component; an HVAC system component controller electrically connected to the HVAC system component to control the operation of the HVAC system component; and a PI algorithm. The PI algorithm uses PI gain constants calculated from the open loop transfer function of the HVAC system component.

Abstract: A thermostat (10) for sensing the ambient temperature in an environment includes an enclosure (100) housing a temperature sensor (20) for sensing the temperature within the enclosure, a temperature display device (30), a liquid crystal display (LCD) backlight (40) operative in its on state to illuminate the temperature display. A controller (50) operatively associated with the thermostat monitors the current on/off state of the backlight and the length of time the backlight has been in its current state, estimates a temperature correction factor using a simplified Discrete Kalman Filter estimator, and applies the temperature correction factor to correct the sensed temperature for the heat generated by the backlight (40).

Abstract: A temperature regulating system utilizes changing energy price information to alter the system operation. A performance index value is determined that indicates a balance between a user's preference for maintaining a setpoint temperature and a need for maintaining energy cost savings. The performance index value is related to the current energy price and the system automatically responds to rising energy prices by reducing system operation in a manner that provides cost savings according to a user's specified preference for weighting temperature comfort levels compared to energy cost savings. According to the described example, an optimal control solution is used to determine the performance index value.

Abstract: A feedforward control method for an absorption chiller includes determining the disturbance transfer function, determining the capacity valve transfer function, measuring the actual disturbance, and implementing the feedforward control function in a feedforward controller. The feedforward control function is represented by the ratio of the disturbance transfer function divided by the capacity valve transfer function. The disturbance transfer function and the capacity valve transfer function are measured by applying a known amplitude input perturbation to the disturbance or capacity valve and recording the resulting perturbation in the output leaving chilled water temp. The disturbance transfer function is then the ratio of the delta leaving chilled water temperature divided by the delta change in the disturbance. The capacity transfer function is the ratio of the delta leaving chilled water temperature divided by the delta change in the capacity valve.

Abstract: Data points are determined for an absorption chiller system which relate a position of the capacity valve to the heat input into the system. A continuous curve is determined which estimates the relationship between the position of the capacity valve and the heat input for all of the data points and all the points in between. The slope of this curve is the valve gain. The error for the system is defined as the difference between the setpoint and the leaving chilled water temperature. The leaving chilled water temperature of the system is measured to determine the actual error for the system, after which a linearizing gain derived as a function of the inverse of the valve gain is used in the system control algorithm to linearize the overall valve gain, thereby eliminating capacity valve hunting and producing an improved transient response.

Abstract: A system for estimating energy cost savings during curtailment periods, for example, determines an estimated temperature in the zone during the period of interest as if the thermostat were set at a temperature different than the actual set point temperature. By determining a difference in the estimated temperature in the zone and the actual temperature over time, the amount of energy savings can be estimated. Applying real time energy cost data to the estimated energy savings provides a real time estimation of actual cost savings during a selected period. The inventive estimation technique includes determining an equilibrium condition for the zone as part of the estimation process.

Abstract: A method of controlling the capacity of an absorption chiller by regulating the heat input to a generator in response to a selected one of two system variables. The first variable involves the measured chilled water temperature leaving the system evaporator and the second involves the calculated solution concentration that is being returned to the absorber. Data relating to each variable is sent to a selector where it is processed so that the data can be used to control the heat input to the generator. The temperature data is used to control the heat input during normal chiller operation, however, the selector changes over control to the concentrate related data when the solution concentration level approaches the solution crystallization limit.

Abstract: A method for programming a thermostat, comprising the steps of providing a thermostat programmed to convert programming codes into time-temperature schedules; determining a desired time-temperature schedule; developing a programming code corresponding to the desired time-temperature schedule; and entering the programming code into the thermostat, whereby the programming code is translated into the desired time-temperature schedule. The schedule and programming code can advantageously be determined by a user by accessing a server via computer network, on a suitably programmed personal computer, by telephone, or by any other suitable method of allowing the user access to software for determining the schedule and developing the desired code.

Abstract: A temperature regulating system utilizes changing energy price information to alter the system operation. A performance index value is determined that indicates a balance between a user's preference for maintaining a setpoint temperature and a need for maintaining energy cost savings. The performance index value is related to the current energy price and the system automatically responds to rising energy prices by reducing system operation in a manner that provides cost savings according to a user's specified preference for weighting temperature comfort levels compared to energy cost savings. According to the described example, an optimal control solution is used to determine the performance index value.

Abstract: A system for estimating energy cost savings during curtailment periods, for example, determines an estimated temperature in the zone during the period of interest as if the thermostat were set at a temperature different than the actual set point temperature. By determining a difference in the estimated temperature in the zone and the actual temperature over time, the amount of energy savings can be estimated. Applying real time energy cost data to the estimated energy savings provides a real time estimation of actual cost savings during a selected period. The inventive estimation technique includes determining an equilibrium condition for the zone as part of the estimation process.