Digital control of smart structures

A device for controlling strain in a foundation member comprising an assembly being a patch containing a piezoelectric sensor and a piezoelectric actuator located in operative relative relationship, local control electronics, means for operatively connecting the local control electronics between the sensor and the actuator, means for placing the assembly in operative relationship with a foundation member whereby the sensor detects a strain in the foundation member and whereby the local control electronics processes a signal from the sensor and activates the actuator, and the actuator imparts a force to the foundation member, the local control electronics including a programmable digital compensator having means for periodically storing and updating an input list of most recent input values and an output list of most recent output values, and means for determining a new output value as a weighted algebraic sum of selected ones of the input and output values of the input and output lists.

A device for controlling strain in a foundation member comprising an assembly being a patch containing a piezoelectric sensor and a piezoelectric actuator located in operative relative relationship, means for placing the assembly in operative relationship with the foundation member whereby the sensor detects a strain in the foundation member and whereby the actuator imparts a selected force to the foundation member, means for connecting local control electronics in operative relationship with the assembly, further control means located remotely from the assembly and connected with the local control electronics, wherein said further control means provides at least one of power for the local control electronics and a central command communication for the local control electronics, and the local control electronics includes a programmable digital compensator having means for periodically storing and updating an input list of most recent input values and an output list of most recent output values, and means for determining a new output value as a weighted algebraic sum of selected ones of the input and output values of the input and output lists, the compensator being programmable in response to signals from the further control means.

A method of controlling strain in a foundation member comprising locating an assembly being a pre-formed patch including a base, a piezoelectric sensor and a piezoelectric actuator coupled to the base;

• locating the assembly in operative relative relationship on the foundation member;
• and connecting control electronics in operative relationship with the assembly, whereby the sensor detects a strain in the foundation member and whereby the actuator imparts a strain-inducing force to the foundation member;
• and digitally programming a digital compensator in the control electronics thereby to permit control of strain in the foundation member.

A method for controlling strain in a foundation member comprising the steps of providing an assembly comprising a piezoelectric sensor and a piezoelectric actuator;

• locating the assembly in operative relative relationship with the foundation member;
• connecting local control electronics between the sensor and the actuator without coupling strain between the assembly and the local control electronics, whereby when the sensor detects a strain in the foundation member the control electronics processes a signal from the sensor for the actuator, and the actuator imparts a selected force to the foundation member, and digitally programming a compensator in the control electronics for implementing a difference equation whereby sequential outputs of the compensator are weighted algebraic sums of prior inputs and outputs of the compensator, thereby to permit control of the foundation member.