# The sensor

Which are the sensors used by Capto?

Capto is equipped with nine measurement sensors and five calibration sensors.

The measurement sensors are 3 magnetometers, 3 gyroscopes and 3 accelerometers. The calibration sensors are 3 thermometers, a barometer and a hygrometer. The latter are used to adjust the measurements as the environmental conditions change. Capto is equipped with a powerful calculation processor that performs on-board processing of the most significant quantities and

the first step of the sensor-fusion algorithm.

What are the accuracy of Capto sensors?

The accuracy of Capto's sensors is very high. For the magnetometer is 5 micro Tesla, for gyroscope is 5 hundredths of a degree per second, for the accelerometer, better than 5 thousandths of degree. This means that it is possible to obtain the estimates of the quantities derived with great precision.

What can be measured with Capto?

With Capto we can measure directly: 3 intensities of the magnetic field, 3 angular speeds and 3 accelerations. From these, with the integration of the gyroscopes we obtain angles values. With the integration of the accelerometers we obtain the movement speeds and, with further integration, the putter positions.

Why is frequency (FPS) so important?

The quality of the measurement of a physical phenomenon

depends on the following main factors:

1) number of sensors

2) sensor accuracy

3) frequency of measurements

The number of sensors determines the independent quantities acquired and therefore the reliability and precision of the measurement. In Capto there are nine measurement sensors and five calibration sensors.

Each of the measurement sensors provides an independent value.

Capto combines the information of all the sensors through a complex sensor fusion algorithm. In the case of vision systems there is only one measuring sensor, like the camera. Even in the case of ultrasound systems there is only one sensor, even if apparently they seem three. In fact, none of the three sensors is able

to provide an independent measured value.

The accuracy of each sensor expresses how much the measured value looks like true. In Capto we measure directly 3 accelerations, 3 angular speeds and

3 magnetic intensities, all with very high precision.

The number of measurements determines the level of sampling of the phenomenon.

In the putting strokes you have speed, about 2 meters per second at the impact and angular speeds of about 60 degrees per second for the shaft.

This means that Capto (at 400 Hz), close to impact, acquires a data packet every five millimeters of trajectory and 0.15 degrees of shaft.

A 70 Hz system acquires data every 28.5 mm (more than half a ball) and 1 degree of shaft. Every value that is found between two successive acquisitions is interpolated and, in a certain sense, supposed. The same point of impact canâ€™t be identified with an accuracy greater than the acquisition step.

Finally, it must be considered that the contact time between the ball and putter varies between 0.2 and 0.4 milliseconds and therefore the more we ascend with the frequencies the better we know the physics of the impact.