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179 changes: 179 additions & 0 deletions Availability Modelling.md
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# Availability Modelling

# Introduction

sdvsv

# Model Parameters

## Performance Time ($$t_p$$)

The average time a T-Stick performance lasts given in hours.

## Performer Intensity ($$j_p$$)

The intensity of the performance, rough indicator of the impact of a performance on the reliability of certain components.

## Simulation Parameters

These additional parameters may be used for simulation, when wanting to take into account technician availability. It is not used for PIR calculations for the T-Stick evaluation though.

### Performance Frequency ($$p_f$$)

The average amount of performances per month. It can be used along side ***maintenance time between performance***, and ***technician availability*** to compute the ***interruption percentage*.**

### Technician Availability ($$A_{tech}$$)

The average amount of hours a technician/luthier is available to fix any issues an artist can’t fix with their instrument per month.

### Technician Turnaround ($$t_{tech}$$)

The average amount of business days it takes for the technician/luthier to return the instrument to the artist/musician.

## Model Inputs

### Maintenance Time between performances ($$t_m$$)

The amount of time an artist/musician spends maintaining the T-Stick in between performances, given in hours.

### Mean time to repair for T-Stick Components ($$MTTR_c$$)

Mean time to repair/replace for T-Stick components in hours

### Mean time between failure for T-Stick Components ($$MTBF_c$$)

Mean time between failure of T-Stick components in hours

### Maintenance actions between performance

The actions the artist/musicians take when maintaining their instrument.

### Available tools (T)

The available equipment an artist has on hand for maintaining and fixing their instrument.

# Compute Practice Interruption Rate (PIR)

## 1. Computing MTBF and failure rate of T-Stick

To compute the Practice interruption rate we must first compute the failure rate of the T-Stick ($$ \lambda_{tstick}$$). We do this by adding the failure rate of each component.

$$$
\begin{equation}
\lambda_{tstick} = \lambda_{esp32} + \lambda_{fsr}+\lambda_{imu}+\lambda_{button}+\lambda_{capsense}+\lambda_{resistor}+\lambda_{touchsensor}+\lambda_{battery}+\lambda_{connectors}
\end{equation}
$$$

where $$\lambda_i$$ is the failure rate of component *i*.

The failure rates for several components such as:

* FSR
* Resistor
* IMU
* Capsense Board
* ESP32 Board
* Battery

can be estimated using a combination of the [FIDES reliability prediction too](https://www.fides-reliability.org/)l, the [MIL-217F Handbook](https://drive.google.com/file/d/1QNUiTOAwJebwC-bk0FJWB0jD3I6XFxFi/view?usp=drive_link), and the [NPRD-91](https://drive.google.com/file/d/1QPMqClW2nHY4U9tmMO5Lzc11RDF2Oeoc/view?usp=sharing). The MTBF of the connectors is taken from the performance model.

We compute the MTBF of the t stick by taking the reciprocal of the failure rate.

$$$
\begin{equation}
MTBF_{tstick} = \frac{1}{\lambda_{tstick}}
\end{equation}
$$$

## 3. Compute Mean Performances between failure (MPBF)

We can then compute the mean performances between failure ($$MTBF_{tstick}$$) by dividing the $$MTBF_{tstick}$$ by the **performance time (**$$t_P$$)

$$$
\begin{equation}
MPBF = \frac{MTBF_{tstick}}{t_p}
\end{equation}
$$$

## 4. Compute PIR

We calculate the practice interruption rate by taking the reciprocal of $$MPBF$$.

$$$
\begin{equation}
PIR = \frac{1}{MPBF}
\end{equation}
$$$

Using Eq.5, Eq.6 and Eq.7 we can simplify the PIR expression.

$$$
\begin{align*}
PIR &= t_p(\frac{1}{MTBF_{tstick}}) \tag{Using Eq.3}\\
&= t_p(\lambda_{tstick}) \tag{Using Eq.6} \\
\end{align*}
$$$

Hence an alternative expression for the Practice Interruption rate is:

$$$
\begin{equation}
PIR = t_p(\lambda_{tstick})
\end{equation}
$$$

In simple words the **Practice Interruption Rate** is the:

$$$
\text{average performance time} \times \text{failure rate of the t-stick}
$$$

# Compute Performance/Maintenance Ratio (PMR)

Computing the Performance/Maintenance Ratio (PMR) is a matter of taking the $$MTBF_{tstick}$$ computed in the PIR model and dividing that by the average maintenance time.

## Computing Average Maintenance time ($$T_m$$)

To compute average maintenance time we consider the mean time to repair ($$MTTR_c$$) of each component and the failure rate of each component ($$\lambda_c$$). We can then take a weighted average of all the repair by taking into account each components contribution to the total failure rate.

$$$
\begin{equation}
T_m = \sum_{c=0}^n \frac{\lambda_c}{\lambda_{tstick}}(MTTR_c)
\end{equation}
$$$

## Compute PMR

To compute PMR we divide the $$MTBF_{tstick}$$ by the average maintenance time ($$T_m$$).

$$$
\begin{equation}
PMR = \frac{MTBF_{tstick}}{T_m}
\end{equation}
$$$

# Compute Direct Maintenance Costs (DMC)

We can also look at the direct maintenance cost of the T-Stick which we define as the dollars spent on maintaining the T-Stick per performance hour.

## Compute Mean Repair Cost of the T Stick

The mean repair cost of the T-Stick ($$MRC_{tstick}$$) is computed the same way the average maintenance time, by using a weighted average of the mean repair cost of each component.

$$$
\begin{equation}
MRC_{tstick} = \sum_{c=0}^n \frac{\lambda_c}{\lambda_{tstick}}(MRC_c)
\end{equation}
$$$

## Compute DMC

To compute DMC we divide the mean repair cost by the mean time between failure of the T-Stick ($$MTBF_{tstick}$$)

$$$
\begin{equation}
DMC = \frac{MRC_{tstick}}{MTBF_{tstick}}
\end{equation}
$$$


5 changes: 5 additions & 0 deletions Gesture Algorithms.md
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# Gesture Algorithms

# Introduction

Many different gesture algorithms have been used in the T-Stick. This section will list links to documentation for these algorithms. Check the [T-Stick Designs](./T-Stick%20Designs.md) to find out which algorithm is compatible with which T-Stick version.
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