Actuator Control for Musical Instrument Key Stability
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Solution Overview
Problem
Existing automatic performance systems for musical instruments, such as auto player pianos, face issues with operational disharmony between key and actuator actions, leading to unstable and inaccurate performances, especially during quick performance styles, resulting in unwanted noise due to the lack of accurate correlation between key and solenoid movements.
Innovation Solution
A system comprising sensors to detect the motion of both the performance operator (key) and the actuator's movable member, with a processor that determines and corrects for any separation between them, ensuring continuous contact and harmonized action to prevent noise and ensure stable performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If servo control is performed based on key stroke position/velocity and plunger position/velocity feedback, then driving accuracy of solenoids is improved, but operational disharmony between key and solenoid action occurs in quick performance styles
Solution Approach 1:
The system uses feedback from both key sensors (detecting key stroke position and velocity) and plunger sensors (detecting plunger position and velocity) to perform servo control. The processor continuously monitors the positional relationship between keys and plungers, adjusting solenoid drive commands in real-time to maintain proper contact and prevent separation, thereby resolving the operational disharmony while preserving driving accuracy.
2Productivity
If solenoids drive keys at high speed for quick performance styles, then productivity is improved, but keys and plungers separate and hit each other generating noise
Solution Approach 1:
The feedback mechanism continuously monitors the actual positions of keys and plungers during high-speed operation. When separation is detected, the processor adjusts the solenoid drive commands to bring the plunger back into contact with the key, preventing the harmful impact noise while maintaining high performance speed capability.
Solution Approach 2:
The system performs preliminary detection of potential separation conditions using the sensors before actual separation and noise generation occurs. The processor proactively adjusts drive commands to prevent separation, applying counter-action in advance to offset the harmful effect of key-plunger separation and impact noise.
3Device complexity
If conventional auto player piano construction is used without contact monitoring, then device complexity is reduced, but performance stability deteriorates during rapid key movements
Solution Approach 1:
The system incorporates sensors on both keys and plungers to provide continuous feedback on their positional relationship. The processor uses this feedback to dynamically adjust solenoid drive commands, ensuring stable performance during rapid key movements. The added complexity of sensors and feedback control is justified by the significant improvement in performance stability.
Data Source
AI summary
An actuator includes a movable member that, when moving, abuts against a key (performance operator) to move the key. A first sensor detects motion of the key. A second sensor detects motion of the movable member. A processor determines, based on outputs of the sensors, whether or not the key and the movable member are currently in a mutually separated state. When the key and the movable member are in the mutually separated state, the processor controls the actuator in such a manner that the key and the movable member are in contact with each other. When the key and the movable member are not in the mutually separated state, the processor controls the actuator by use of feedback information based on the output of the first sensor, whereas, in the mutually separated state, the actuator is controlled by feedback information based on at least the second sensor output.