Control system for a sensor assembly

Abstract

In a method of expelling contaminants from a sensor, a change is measured in a resonant frequency of a sensor assembly to detect contaminants on a surface of the sensor assembly. A change is measured in a frequency response of the sensor assembly to determine a presence and an amount of the contaminants on the surface. A cleaning mode is determined based on an amount of the contaminants on the surface. A cleaning is determined phase based on the amount of the contaminants on the surface. A cleaning control signal is provided to an actuator of the sensor assembly to expel the contaminants from the surface.

What is claimed is: 
     
         1 . A method of expelling contaminants from a sensor, the method comprising:
 measuring a change in a resonant frequency of a sensor assembly to detect contaminants on a surface of the sensor assembly;   measuring a change in a frequency response of the sensor assembly to determine a presence and an amount of the contaminants on the surface;   determining a cleaning mode based on an amount of the contaminants on the surface;   determining a cleaning phase based on the amount of the contaminants on the surface; and   providing a cleaning control signal to an actuator of the sensor assembly to expel the contaminants from the surface.   
     
     
         2 . The method of  claim 1 , further comprising vibrating the actuator at a resonant frequency of the sensor assembly to expel the contaminants from the surface. 
     
     
         3 . The method of  claim 1 , further comprising determining whether a temperature of the actuator exceeds a temperature threshold based on the change in the frequency response of the sensor assembly, disabling the cleaning control signal and initiating a cooling procedure to cool the actuator responsive to the temperature of the actuator exceeding the temperature threshold. 
     
     
         4 . The method of  claim 1 , further comprising determining whether the actuator has a fault based on the change in the frequency response of the sensor assembly at different voltage levels, and disabling the cleaning control signal responsive to the fault.