Torque measuring piezoelectric device and method

A method for self-diagnosis of a piezoelectric strain transducer, said method comprising the steps of:

• under no-load conditions, operating said transducer in an oscillatory mode for generating, at a first electrode, an oscillatory signal defining a frequency;
• measuring one of said frequency and the amplitude of said oscillatory signal under said no-load conditions;
• under said no-load conditions, applying a known thermal energy to said transducer, for generating strain in said transducer;
• during said step of applying a known thermal energy, measuring said one of said frequency and the amplitude of said oscillatory signal;
• determining the difference between said first and second one of said frequency and amplitude of said oscillatory signal;
• comparing said difference with at least one stored value, and deeming said transducer to be operable if said difference is near enough to said stored value.

A method for self-diagnosis of a piezoelectric strain transducer, said method comprising the steps of:

• under no-load conditions, operating said transducer in an oscillatory mode for generating, at a first electrode, an oscillatory signal defining a frequency;
• measuring one of said frequency and the amplitude of said oscillatory signal under said no-load conditions;
• under said no-load conditions, applying a voltage to a secondary piezoelectric transducer affixed to said piezoelectric strain transducer, for generating strain in said piezoelectric strain transducer;
• during said step of applying a known voltage to said secondary piezoelectric transducer, measuring said one of said frequency and the amplitude of said oscillatory signal;
• determining the difference between said first and second one of said frequency and amplitude of said oscillatory signal;
• comparing said difference with at least one stored value, and deeming said transducer to be operable if said difference is near enough to said stored value.