digital-brain/content/zettels/position_sensors.md

+++ title = "Position Sensors" author = ["Thomas Dehaeze"] draft = false +++

Backlinks

• [A review of nanometer resolution position sensors: operation and performance]({{< relref "fleming13_review_nanom_resol_posit_sensor" >}})
• [Measurement technologies for precision positioning]({{< relref "gao15_measur_techn_precis_posit" >}})
• [Inertial Sensors]({{< relref "inertial_sensors" >}})
• [Sensors]({{< relref "sensors" >}})
• [Collocated Control]({{< relref "collocated_control" >}})

Tags

[Inertial Sensors]({{< relref "inertial_sensors" >}}), [Force Sensors]({{< relref "force_sensors" >}}), [Sensor Fusion]({{< relref "sensor_fusion" >}}), [Signal Conditioner]({{< relref "signal_conditioner" >}}), [Signal to Noise Ratio]({{< relref "signal_to_noise_ratio" >}})

Reviews of Relative Position Sensors

• Fleming, A. J., A review of nanometer resolution position sensors: operation and performance (Fleming 2013) ([Notes]({{< relref "fleming13_review_nanom_resol_posit_sensor" >}}))

Table 1: Characteristics of relative measurement sensors collette11_review

Technology	Frequency	Resolution	Range	T Range
LVDT	DC-200 Hz	10 nm rms	1-10 mm	-50,100 °C
Eddy current	5 kHz	0.1-100 nm rms	0.5-55 mm	-50,100 °C
Capacitive	DC-100 kHz	0.05-50 nm rms	50 nm - 1 cm	-40,100 °C
Interferometer	300 kHz	0.1 nm rms	10 cm	-250,100 °C
Encoder	DC-1 MHz	1 nm rms	7-27 mm	0,40 °C
Bragg Fibers	DC-150 Hz	0.3 nm rms	3.5 cm	-30,80 °C

Table 2: Summary of position sensor characteristics. The dynamic range (DNR) and resolution are approximations based on a full-scale range of 100um and a first order bandwidth of \(1 kHz\) fleming13_review_nanom_resol_posit_sensor

Sensor Type	Range	DNR	Resolution	Max. BW	Accuracy
Metal foil	\(10-500 \mu m\)	230 ppm	23 nm	1-10 kHz	1% FSR
Piezoresistive	\(1-500 \mu m\)	5 ppm	0.5 nm	>100 kHz	1% FSR
Capacitive	\(10 \mu m\) to \(10 mm\)	24 ppm	2.4 nm	100 kHz	0.1% FSR
Electrothermal	\(10 \mu m\) to \(1 mm\)	100 ppm	10 nm	10 kHz	1% FSR
Eddy current	\(100 \mu m\) to \(80 mm\)	10 ppm	1 nm	40 kHz	0.1% FSR
LVDT	\(0.5-500 mm\)	10 ppm	5 nm	1 kHz	0.25% FSR
Interferometer	Meters		0.5 nm	>100kHz	1 ppm FSR
Encoder	Meters		6 nm	>100kHz	5 ppm FSR

Capacitive Sensors and Eddy-Current sensors are compare here.

Capacitive Sensor

Description:

• http://www.lionprecision.com/tech-library/technotes/cap-0020-sensor-theory.html
• https://www.lionprecision.com/comparing-capacitive-and-eddy-current-sensors

Manufacturers	Links	Country
Micro Sense	link	USA
Micro-Epsilon	link	Germany
PI	link	Germany
Unipulse	link	Japan
Lion-Precision	link	USA
Fogale	link	USA
Queensgate	link	UK
Capacitec	link	USA

Inductive Sensor (Eddy Current)

Manufacturers	Links
Micro-Epsilon	link	Germany
Lion Precision	link	USA
Cedrat	link	France
Kaman	link	USA
Keyence	link	USA

Inductive Sensor (LVDT)

Manufacturers	Links	Country
Micro-Epsilon	link	Germany
Keyence	link	USA

Interferometers

Manufacturers	Links	Country
Attocube	link	Germany
Zygo	link	USA
Smaract	link	Germany
Qutools	link	Germany
Renishaw	link	UK
Sios	link	Germany
Keysight	link	USA

Table 3: Characteristics of Environmental Units

	Temperature (\(\pm\ ^oC\))	Pressure (\(\pm\ hPa\))	Humidity \(\pm\% RH\)	Wavelength Accuracy (\(\pm\ \text{ppm}\))
Attocube	0.1	1	2	0.5
Renishaw	0.2	1	6	1
Picoscale	0.2	2	2	1

(Jang and Kim 2017)

{{< figure src="/ox-hugo/position_sensor_interferometer_precision.png" caption="Figure 1: Expected precision of interferometer as a function of measured distance" >}}

Linear Encoders

Manufacturers	Links	Country
Heidenhain	link	Germany
MicroE Systems	link	USA
Renishaw	link	UK

Bibliography

Fleming, Andrew J. 2013. “A Review of Nanometer Resolution Position Sensors: Operation and Performance.” Sensors and Actuators a: Physical 190 (nil):106–26. https://doi.org/10.1016/j.sna.2012.10.016.

Jang, Yoon-Soo, and Seung-Woo Kim. 2017. “Compensation of the Refractive Index of Air in Laser Interferometer for Distance Measurement: A Review.” International Journal of Precision Engineering and Manufacturing 18 (12):1881–90. https://doi.org/10.1007/s12541-017-0217-y.