Method of estimating solenoid heat accumulation and compensating for solenoid force loss

In an electronic player-piano system having an electronic controller to control the force with which keys are activated by a solenoid driver in response to music composition data, the improvement comprising:

• a temperature compensation routine executable by said electronic controller;
• wherein said temperature compensation routine maintains a heat value for each solenoid being driven;
• wherein said heat value is periodically increased in response to activation forces applied to the solenoid of each key;
• wherein said heat value is periodically decreased by an amount in response to the thermal heat dissipation of each solenoid;
• wherein the thermal dissipation value to be subtracted from said heat value is determined by dividing said heat value by a heat dissipation factor;
• wherein said routine calculates a gain value for each solenoid based on said heat value;
• and
• wherein said gain value utilized within the routine modulates the outputs for driving said solenoids to prevent thermally induced force roll-off within the solenoids.

A method of temperature compensating the power being applied to a solenoid based on an estimate of the heat accumulated within said solenoid, comprising:

• initializing a heat quantity value for said solenoid at ambient conditions;
• reducing said heat quantity value by a given percentage;
• accumulating heat within said heat quantity value by adding a quantity of heat in response to the power applied to said solenoid;
• calculating a temperature compensation gain value based on said heat quantity value;
• multiplying the power value to be applied to said solenoid by said temperature compensation gain value to prevent solenoid force roll-off as solenoid temperature increases;
• and
• periodically repeating the above steps following said initialization to maintain an updated value of temperature compensation.

A method of estimating accumulated heat for a device subject to coil heating during activations thereof, comprising:

• initializing a heat quantity value for said device at ambient conditions;
• periodically adding a quantity of heat to the heat quantity value if the associated device coil is active;
• periodically reducing the heat quantity value toward ambient by an amount in response to said heat quantity value as subject to a heat dissipation factor,
• wherein the heat quantity is reduced according to the equation:
• Heat[coil]=heat[coil]−(heat[coil]/heatConstant);
• and
• wherein heat[coil] is an array of heat quantity values for each coil within the array and the heatCostant is determined according to the heat dissipation for a given coil.