UP | HOME

# Encoder Renishaw Vionic - Test Bench
Author: Dehaeze Thomas

## Table of Contents

- 1. Encoder Model
- 2. Test-Bench Description
- 3. Measurement procedure
- 4. Measurement Results

You can find below the document of:

- Vionic Encoder
- Linear Scale

We would like to characterize the encoder measurement system.

In particular, we would like to measure:

- Bandwidth/dynamics of the sensor
- Power Spectral Density of the measurement noise
- Linearity/resolution of the sensor

## 1 Encoder Model

The Encoder is characterized by its dynamics \(G_m(s)\) from the “true” displacement \(y\) to measured displacement \(y_m\). Ideally, this dynamics is constant over a wide frequency band with very small phase drop.

It is also characterized by its measurement noise \(n\) that can be described by its Power Spectral Density (PSD).

The model of the encoder is shown in Figure 1.

Figure 1: Model of the Encoder

## 2 Test-Bench Description

To measure the noise \(n\) of the encoder, one can rigidly fix the head and the ruler together such that no motion should be measured. Then, the measured signal \(y_m\) corresponds to the noise \(n\).

In order to measure the linearity, we have to compare the measured displacement with a reference sensor with a known linearity. An interferometer or capacitive sensor should work. An actuator should also be there so impose a displacement.

## 3 Measurement procedure

## 4 Measurement Results

Author: Dehaeze Thomas

Created: 2020-12-16 mer. 14:07