Active feed forward power control loop
First Claim
1. A feed forward power control loop for a body tissue stimulation system, comprising;
- an implantable device including circuitry and electrodes adapted to provide stimulation to body tissue; and
an external device adapted to provide power to said implantable device, wherein said external device includes a mathematical model adapted to generate an estimate of the amount of power required by said implantable device, wherein the mathematical model does not require feedback from the implantable device to generate the estimate.
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Abstract
A feed forward power control loop is provided for a tissue stimulation system. The tissue stimulating system includes an external device and an implantable device. Only the amount of power required by the implantable device is transmitted across a transcutaneous transmission link to the implantable device from the external device, thereby reducing power fluctuations within the implantable device, and reducing the amount of power expended by the external device. In one embodiment, the power control loop is used with a cochlear stimulating system that includes an externally wearable signal receiver and processor (WP) and an implanted cochlear stimulator (ICS). The feed forward power control loop predicts the power requirements of the ICS. The prediction is used to determine the level of RF power to be transmitted by the WP. The transmitted RF power is received by the ICS and is stored in a “tank” capacitor that is used as a power source within the ICS for stimulating the cochlea and for powering the circuits within the ICS. The predictions of the ICS power requirements are based on a mathematical model and independent variables originating within the WP. The form of the mathematical model is based on a current model of the ICS. The coefficients of the mathematical model are obtained from the application of multiple regression analysis to a system of equations. The system of equations is derived from a plurality of measurements of the dependent and independent variables of the equation, recorded at different system operating points, and on the form of the mathematical model.
82 Citations
34 Claims
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1. A feed forward power control loop for a body tissue stimulation system, comprising;
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an implantable device including circuitry and electrodes adapted to provide stimulation to body tissue; and
an external device adapted to provide power to said implantable device, wherein said external device includes a mathematical model adapted to generate an estimate of the amount of power required by said implantable device, wherein the mathematical model does not require feedback from the implantable device to generate the estimate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A tissue stimulating system comprising:
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an implantable part including a power requirement an external part including;
means for computing an estimate of the power requirement of the implantable part; and
means for providing power to the implantable part based on the estimate of the power requirement of the implantable part;
wherein the means for computing an estimate does not require feed-back from the implantable part. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. A method for conserving power within a tissue stimulating system, the system comprising an external device and an implantable device, wherein the external device includes a power source for providing operating power for the system, and wherein the external device further includes means for transmitting power to the implantable device, wherein the implantable device includes electrodes for stimulating tissue with electrical power derived from the power transmitted to the implantable device from the external device, the method comprising:
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estimating the power requirements of the implantable device, wherein the estimating is performed within the external device, and wherein the estimating does not require feed-back of data from the implantable device; and
adjusting the amount of power transmitted to the implantable device so that the amount of power transmitted to the implantable device corresponds to the estimate of the power requirements of the implantable device. - View Dependent Claims (32, 33, 34)
obtaining the mathematical model, comprising;
collecting measurements of the dependent variable and the independent variables of the mathematical model; and
solving for coefficients of the mathematical model using a multiple regression algorithm;
implementing the mathematical model within the external device to estimate the power required by the implantable device.
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34. The method of claim 33 wherein the step of collecting measurements, comprises;
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1) implanting the implantable device;
2) connecting test equipment to the tissue stimulation system;
3) stimulating the tissue stimulation system with speech noise;
4) recording the speech noise level (dBSPL);
5) recording the RF power level;
6) recording Vtank (where Vtank is the voltage on the tank capacitor within the implantable device);
7) repeating steps 2 through 6 at different speech noise; and
8) repeating steps 2 through 7 at different RF power levels.
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Specification