Fault tolerant control of a terminal unit in a climate control system

Abstract

A method for controlling a terminal unit in a climate control system includes detecting a stuck position of a first actuator in the terminal unit; receiving a command signal identifying a commanded capacity; and controlling a second actuator in the terminal unit in response to the stuck position of the first actuator and the commanded capacity.

What is claimed is: 
     
         1 . A method for controlling a terminal unit in a climate control system, the method comprising:
 detecting a stuck position of a first actuator in the terminal unit;   receiving a command signal identifying a commanded capacity; and   controlling a second actuator in the terminal unit in response to the stuck position of the first actuator and the commanded capacity.   
     
     
         2 . The method of  claim 1  wherein:
 controlling the second actuator comprises: 
 accessing an adaptive coordination map, the adaptive coordination map associating the commanded capacity with a second actuator drive signal for the stuck position of the first actuator; and 
 applying the second actuator drive signal to the second actuator. 
 
     
     
         3 . The method of  claim 1  wherein:
 controlling the second actuator comprises: 
 computing a second actuator drive signal in response to the commanded capacity and the stuck position of the first actuator; and 
 applying the second actuator drive signal to the second actuator. 
 
     
     
         4 . The method of  claim 1  wherein:
 the detecting the stuck position of the first actuator in the terminal unit includes providing a range of drive signals to the first actuator; and 
 determining if the first actuator responds to the range of drive signals. 
 
     
     
         5 . The method of  claim 4  wherein:
 determining if the first actuator responds to the range of drive signals includes sensing movement of the first actuator. 
 
     
     
         6 . The method of  claim 4  wherein:
 determining if the first actuator responds to the range of drive signals includes sensing fluid flow or temperature in the terminal unit. 
 
     
     
         7 . The method of  claim 4  wherein:
 determining if the first actuator responds to the range of drive signals includes determining an output capacity of the terminal unit. 
 
     
     
         8 . The method of  claim 7  wherein:
 determining the output capacity of the terminal unit includes sensing discharge air temperature of the terminal unit. 
 
     
     
         9 . A terminal unit system comprising:
 a controller; and   a terminal unit having an actuator;   the controller configured to control the actuator, the controller configured to perform operations comprising:   detecting a stuck position of a first actuator in the terminal unit;   receiving a command signal identifying a commanded capacity; and   controlling a second actuator in the terminal unit in response to the stuck position of the first actuator and the commanded capacity.   
     
     
         10 . The terminal unit system of  claim 9  wherein:
 controlling the second actuator comprises: 
 accessing an adaptive coordination map, the adaptive coordination map associating the commanded capacity with a second actuator drive signal for the stuck position of the first actuator; and 
 applying the second actuator drive signal to the second actuator. 
 
     
     
         11 . The terminal unit system of  claim 9  wherein:
 controlling the second actuator comprises: 
 computing a second actuator drive signal in response to the commanded capacity and the stuck position of the first actuator; and 
 applying the second actuator drive signal to the second actuator. 
 
     
     
         12 . The terminal unit system of  claim 9  wherein:
 the detecting the stuck position of the first actuator in the terminal unit includes providing a range of drive signals to the first actuator; and 
 determining if the first actuator responds to the range of drive signals. 
 
     
     
         13 . The terminal unit system of  claim 12  wherein:
 determining if the first actuator responds to the range of drive signals includes sensing movement of the first actuator. 
 
     
     
         14 . The method of  claim 12  wherein:
 determining if the first actuator responds to the range of drive signals includes sensing fluid flow or temperature in the terminal unit. 
 
     
     
         15 . The method of  claim 12  wherein:
 determining if the first actuator responds to the range of drive signals includes determining an output capacity of the terminal unit. 
 
     
     
         16 . The method of  claim 15  wherein:
 determining the output capacity of the terminal unit includes sensing discharge air temperature of the terminal unit.