P17363: Player Piano

Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

For this phase, our team's plan was to:


Key Dates:

Prototyping, Engineering Analysis, Simulation

Engineering Requirements Update:

Began preliminary testing components of our system.

Solenoid Testing:

Feasibility: Prototyping, Analysis, Simulation

The following snap shots from the CAD model prove that space is sufficient for a 1" wide solenoid.

This mounting technique will mitigate any damage to existing piano. It is a circular rubber mount on a slider pin which slides into the dowel rod and is pushed outward by a nut to tighten. The following picture shows the nut visible while the next one after that shows the dowel with out the nut.

This is the plunger cap that will be secured to the end of the plunger of each solenoid. It is secured by a rod running though the plunger hole. The hole on the top of the cap is threaded and the wire will be secured by tightening it with the screw.

This allows for the tension of the wire to be easily adjusted instead of the location of the solenoid.

Drawings, Schematics, Flow Charts, Simulations

Bill of Material (BOM)


Confirm that all expenses and contingencies are afforded by the project financial allocation

Test Plans


To test different solenoid types for use on the automated piano.

Solenoid 4 Driver Schematic

Alpha Prototype Electrical Schematic

Force Testing

In order to determine if the solenoids would be powerful enough to actuate a piano key, we must first know how much force it will take to do so. This was done via use of a force varying resistor. The resistor was place between the lever of the piano and a block held in place. The picture below shows the model of the sensor and holding block.

When the given key was actuated it the resistance of the force sensor would change. Through use of a voltage divider and ADC on the uController the resistance value could be determined. The circuit used to connect to the uController is shown below.

Once that was determined a chart provided in the datasheet of the sensor provided the force value. The chart is shown below.

Solenoid Testing

Once the force required was determined the solenoid test fixture could be calibrated. This was done with a pretension-ed spring. A picture of this fixture is shown below.

The distance to tension the spring was found by initially calculating the spring constant. This was done with a basic weight vs. distance analysis. A more in depth view of this process is found in the test procedure document. Once the constant was found the basic Hook's law equation was used to get the distance to tension the spring to. The device was setup and ready to test.

A mounting was designed for each solenoid to be tested. The picture below shows the basic setup.

The solenoid was then connected electrically to the testing circuit. This circuit controlled the solenoid through a PWM signal and a power transistor. The schematic and actualized circuit are shown below.

With each subsystem combined into one test fixture the design verifies most of our largest concerns and is a great starting point to model how the system as a whole will function. A picture of the completed assembly is shown below.

A detailed process including all equations and data values can be found in the link below.

Test Procedure

Design and Flowcharts

The updated flowchart is shown below. The red boxes show which portions were constructed and tested during this phase.

Risk Assessment

Green risks are currently being mitigated while the red signifies that the risk is out of scope. The white risks don't have a specific mitigation method but are a culmination of methods through out the document.

live document.

Design Review Materials

Plans for next phase

Team Plans for next phase

Individual Goals for next phase

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