Automatic Player Piano Hammer Velocity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automatic player pianos face challenges in reproducing tones at target loudness due to differences in hammer weight and acceleration across pitched parts, leading to variations in final hammer velocity and loudness, resulting in low fidelity.
Innovation Solution
The solution involves a controller that adjusts the magnitude of driving signals based on the mass of hammers, ensuring that link works travel on reference trajectories to produce tones at target loudness by varying control parameters and driving signal values accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant control parameters are used for all keys, then device complexity is reduced, but manufacturing precision deteriorates due to individual key variations
Solution Approach 1:
The patent applies local quality by assigning individual control parameters to each key based on its specific characteristics (hammer mass, acceleration profile). Instead of using uniform control for all keys, the system tailors control parameters locally to each key's physical properties, ensuring consistent tone production despite manufacturing variations in hammer weights and key mechanisms.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting control parameters (such as driving signal magnitude, acceleration profiles) according to measured key characteristics. The system varies these parameters across different keys to compensate for individual variations, thereby achieving uniform tone loudness and playback fidelity across the entire keyboard.
2Manufacturing precision
If individual control parameters are assigned to each key, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system employs self-service by automatically measuring and characterizing each key's physical properties during initialization or manufacturing testing. The control parameters are then automatically generated and stored in lookup tables based on these measurements, eliminating the need for manual configuration or complex real-time calculations during playback. This automation reduces operational complexity while maintaining precision.
Solution Approach 2:
The patent applies preliminary action by pre-measuring and pre-configuring control parameters for each key before actual playback operations. The system performs characterization tests during setup, stores the results, and uses these pre-determined parameters during normal operation, thereby avoiding complex real-time adjustments and reducing runtime computational burden.
3Ease of operation
If hammer mass differences are not compensated, then ease of operation is maintained, but manufacturing precision deteriorates
Solution Approach 1:
The system utilizes feedback by measuring actual key acceleration and position during initialization tests, then using this feedback information to calculate and store appropriate control parameters for each key. During playback, the system references these pre-calibrated parameters to automatically compensate for hammer mass differences, maintaining both operational simplicity and high playback fidelity without requiring manual intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach optimizes the force exerted on link works, allowing for high-fidelity tone reproduction by accounting for the mass differences, ensuring that all link works are driven as if they have equal mass, thereby maintaining consistent tone production across different pitched parts.
Implementation Method 1
an automatic player including plural actuators respectively associated with the plural link works and responsive to driving signals so as selectively to exert force on the plural link works
Data Source
AI summary
An automatic player piano is fabricated on the basis of an acoustic piano, and an automatic player is expected to give rise to key motion for reenacting performance with solenoid-operated key actuators; since the hammers of acoustic piano are different in mass, the load against the key motion is also different among the keys; while the motion controller is forcing the keys to travel on reference key trajectories through a servo control loop, the motion controller takes the pitched part into account, and selectively accesses control parameter tables so as to read out the approximate control parameters for the individual keys, whereby the hammers surely reach the target final hammer velocity before striking the strings.