Adaptive acoustic attenuation system having distributed processing and shared state nodal architecture

A multiple input multiple output active acoustic attenuation system for actively attenuating acoustic disturbances in an acoustic plant, the system comprising:

• a plurality of J active acoustic actuators, each associated with an adaptive filter node such that the associated adaptive filter node provides a correction signal to the respective active acoustic actuator and the actuator outputs a secondary acoustic input into the acoustic plant in response to the correction signal;
• a plurality of P error sensors that sense acoustic disturbances in the acoustic plant and generate error signals in response thereto;
• wherein each adaptive filter node includes a nodal digital signal processor that communicates with at least one other nodal digital signal processor contained within another adaptive filter node to provide distributed processing for a multiple input multiple output adaptive filter control model via a shared state nodal architecture;
• and
• the system further comprises:
• a plurality of J-adaptive filter nodes each associated with an acoustic actuator and each outputting a correction signal y.sub.i ›k! that drives the associated acoustic actuator, and wherein each correction signal y.sub.i ›k! is a scalar value generated in accordance with the following expressions:
• y.sub.i ›k!=w.sub.i,i.sup.T ›k!u.sub.i ›k!+w.sub.i-1,i.sup.T ›k!s.sub.i-1,i ›k!+w.sub.i+1,i.sup.T ›k!s.sub.i+1,i ›k!
• s.sub.i,i+1 ›k!=K.sub.i,i+1 ›k!u.sub.i ›k!+K.sub.i-1,i+1 ›k!s.sub.i-1,i ›k!
• s.sub.i,i-1 ›k!=K.sub.i,i-1 ›k!u.sub.i ›k!+K.sub.i+1,i-1 ›k!s.sub.i+1,i ›k!
• where u.sub.i ›k! is a generalized recursive nodal reference signal vector given by ›x.sub.i ›k! . . . x.sub.i ›k-M+1! y.sub.i ›k-1! . . . y.sub.i ›k-M!!.sup.T, M is one-half of the tap length of the recursive nodal reference signal vector u.sub.i ›k!, s.sub.j,l ›k! is the nodal state signal vector transmitted from the j.sup.th adaptive filter node to the l.sup.th adaptive filter node, K.sub.j,l ›k! is a nodal state adaptive parameter matrix for transforming nodal input from the j.sup.th node into a nodal state vector that is transmitted to the l.sup.th node, w.sub.j,i.sup.T is the nodal output adaptive parameter vector which transforms input from the j.sup.th node into information used to generate the correction signal y.sub.i ›k! for the i.sup.th node.

In a multiple input multiple output active acoustic attenuation system having a plurality of digital signal processing nodes, a method of distributing processing and adaptation to attain global minimization of acoustic disturbances in an acoustic plant, the method comprising the steps of:

• sensing acoustic disturbances throughout the acoustic plant with a plurality of error sensors and generating a plurality of error signals in response thereto;
• using a plurality of acoustic actuators to inject secondary acoustic input into the acoustic plant;
• providing a plurality of digital signal processing nodes and generating a nodal state signal vector within the node by filtering a nodal state signal vector generated by another digital signal processing node with a nodal state adaptive parameter matrix;
• generating a correction signal in a plurality of the digital signal processing nodes by filtering a nodal state signal vector generated within another digital signal processing node with a nodal output adaptive parameter vector, each correction signal driving one of the acoustic actuators;
• filtering the error signals through the back propagation of the appropriate electrical and acoustic paths corresponding to the associated intervening digital signal processing nodes, acoustic actuator and the respective error sensors;
• adapting the nodal output adaptive parameter vector via gradient descent adaptation based on filtered error signals;
• and
• adapting the nodal state adaptive parameter matrix via gradient descent adaptation based on filtered error signal vectors;
• wherein the correction signal y.sub.i ›k! for the i.sup.th digital signal processing node is generated in accordance with the following expressions:
• y.sub.i ›k!=w.sub.i,i.sup.T ›k!u.sub.i ›k!+w.sub.i-1,i.sup.T ›k!s.sub.i-1,i ›k!+w.sub.i+1,i.sup.T ›k!s.sub.i+1,i ›k!
• s.sub.i,i+1 ›k!=K.sub.i,i+1 ›k!u.sub.i ›k!+K.sub.i-1,i+1 ›k!s.sub.i-1,i ›k!
• s.sub.i,i-1 ›k!=K.sub.i,i-1 ›k!u.sub.i ›k!+K.sub.i+1,i-1 ›k!s.sub.i+1,i ›k!
• where u.sub.i ›k! is a generalized recursive nodal reference signal vector given by ›x.sub.i ›k! . . . x.sub.i ›k-M+1!y.sub.i ›k-1! . . . y.sub.i ›k-M!!.sup.T, M is one-half of the tap length of the recursive nodal reference signal vector u.sub.i ›k!, s.sub.j,l ›k! is the nodal state signal vector transmitted from the j.sup.th adaptive filter node to the l.sup.th adaptive filter node, K.sub.j,l ›k! is a nodal state adaptive parameter matrix for transforming nodal input from the j.sup.th node into a nodal state vector that is transmitted to the l.sup.th node, w.sub.j,i ›k! is the nodal output adaptive parameter vector which transforms input from the j.sup.th node into information used to generate the correction signal y.sub.i ›k! for the i.sup.th node.