Contenido

• - Rango de medida: dominio") en la magnitud medida en el que puede aplicarse el sensor.

• - Precisión: es el error de medida máximo esperado.

• - Offset o desviación de cero: valor de la variable de salida cuando la variable de entrada es nula. Si el rango de medida no llega a valores nulos de la variable de entrada, habitualmente se establece otro punto de referencia para definir el offset. (down).

• - Linealidad o correlación lineal.

• - Sensibilidad "Sensibilidad (electrónica)") de un sensor: suponiendo que es de entrada a salida y la variación de la magnitud de entrada.

• - Resolución: mínima variación de la magnitud de entrada que puede detectarse a la salida.

• - Rapidez de respuesta: puede ser un tiempo fijo o depender de cuánto varíe la magnitud a medir. Depende de la capacidad del sistema para seguir las variaciones de la magnitud de entrada.

• - Derivas: son otras magnitudes, aparte de la medida como magnitud de entrada, que influyen en la variable de salida. Por ejemplo, pueden ser condiciones ambientales, como la humedad, la temperatura u otras como el envejecimiento (oxidación, desgaste, etc.) del sensor.

• - Repetitividad: error esperado al repetir varias veces la misma medida.

Un sensor es un tipo de transductor que transforma la magnitud que se quiere medir o controlar, en otra, que facilita su medida. Pueden ser de indicación directa (e.g. un termómetro de mercurio) o pueden estar conectados a un indicador (posiblemente a través de un convertidor analógico a digital, un computador y un visualizador) de modo que los valores detectados puedan ser leídos por un humano.

Por lo general, la señal de salida de estos sensores no es apta para su lectura directa y a veces tampoco para su procesado, por lo que se usa un circuito de acondicionamiento, por ejemplo un puente de Wheatstone, amplificadores y filtros electrónicos que adaptan la señal a los niveles apropiados para el resto de los circuitos.

Resolution and precision

The resolution of a sensor is the smallest change in the input magnitude that is seen in the output magnitude. However, precision is the maximum error expected in the measurement.

Resolution may be of lesser value than precision. For example, if when measuring a distance the resolution is 0.01 mm, but the precision is 1 mm, then variations in the measured distance of 0.01 mm can be seen, but it cannot be ensured that there is a measurement error of less than 1 mm. In most cases this excess resolution leads to an unnecessary excess in the cost of the system. However, in these systems, if the measurement error follows a normal or similar distribution, which is common in accidental errors, that is, non-systematic errors, the repeatability could be of a lower value than the precision.

Sensor resolution or measurement resolution is the smallest change that can be detected in the quantity being measured. The resolution of a sensor with digital output is usually the numerical resolution of the digital output. Resolution is related to the precision with which the measurement is made, but they are not the same. The accuracy of a sensor can be considerably worse than its resolution.

• - For example, distance resolution is the minimum distance that can be accurately measured by any distance measuring devices. In a time-of-flight camera, the range resolution is usually equal to the standard deviation (total noise) of the signal expressed in unit length.

• - The sensor may be sensitive to some extent to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment.

However, the precision cannot be a value lower than the resolution, since it cannot be ensured that the error in the measurement is less than the minimum variation in the input magnitude that can be observed in the output magnitude.

Un buen sensor obedece las siguientes reglas:.

• - es sensible a la propiedad medida.

• - es insensible a cualquier otra propiedad que pueda encontrarse en su aplicación, y.

• - no influye en la propiedad medida.

La mayoría de los sensores tienen una función de transferencia lineal. La sensibilidad "Sensibilidad (electrónica)") se define entonces como la relación entre la señal de salida y la propiedad medida. Por ejemplo, si un sensor mide la temperatura y tiene una salida de tensión, la sensibilidad es constante con las unidades [V/K]. La sensibilidad es la pendiente de la función de transferencia. La conversión de la salida eléctrica del sensor (por ejemplo, V) a las unidades de medida (por ejemplo, K) requiere dividir la salida eléctrica por la pendiente (o multiplicar por su recíproco). Además, con frecuencia hay que sumar o restar un desplazamiento. Por ejemplo, debe añadirse -40 a la salida si la salida de 0 V corresponde a una entrada de -40 C.

Para que una señal analógica de un sensor pueda procesarse o utilizarse en un equipo digital, es necesario convertirla en una señal digital, utilizando un conversor analógico-digital.

Sensor deviations

Since sensors cannot replicate an ideal transfer function, several types of deviations can occur that limit the sensor's accuracy:

• - Since the range of the output signal is always limited, the output signal will eventually reach a minimum or maximum when the measured property exceeds the limits. The "full scale range" defines the maximum and minimum values ​​of the measured property.

• - The sensitivity "Sensitivity (electronic)") may differ in practice from the specified value. This is called sensitivity error. This is an error in the slope of a linear transfer function.

• - If the output signal differs from the correct value by a constant, the sensor has an offset or bias error. This is an error in the y-intercept of a linear transfer function.

• - Nonlinearity is the deviation of a sensor's transfer function from a straight line transfer function. Typically, this is defined by the amount the output differs from ideal behavior over the full range of the sensor, often noted as a percentage of the full range.

• - The deviation caused by rapid changes of the measured property over time is a dynamic error "Dynamics (physics)"). This behavior is often described with a bode plot that shows the sensitivity error and phase shift as a function of the frequency of a periodic input signal.

• - If the output signal changes slowly regardless of the measured property, this is defined as drift&action=edit&redlink=1 "Drift (telecommunications) (not yet drafted)"). Long-term drift over months or years is caused by physical changes in the sensor.

• - Noise is a random deviation of the signal that varies with time.

• - A hysteresis error causes the output value to vary depending on the previous input values. If the output of a sensor is different depending on whether a specific input value was reached by increasing or decreasing the input, then the sensor has a hysteresis error.

• - If the sensor has a digital output, the output is essentially an approximation of the measured property. This error is also called digital quantization error.

• - If the signal is monitored digitally, the sampling rate can cause dynamic error, or if the input variable or added noise changes periodically at a frequency close to a multiple of the sampling rate, aliasing errors can occur.

• - The sensor may be sensitive to some extent to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment.

All these deviations can be classified as systematic errors or random errors. Sometimes systematic errors can be compensated for by some type of calibration strategy. Noise is a random error that can be reduced by signal processing, such as filtering, usually at the expense of the dynamic behavior of the sensor.

The following table indicates some types and examples of electronic sensors.

Some quantities can be calculated by measuring and calculating others, for example, the speed of a mobile phone can be calculated from the numerical integration of its acceleration. The mass of an object can be known by the gravitational force exerted on it compared to the gravitational force exerted on an object.

• - Heat detector.

• - Effector.

• - Insteon.

• - Passive infrared sensor.

• - Telecare.

• - X10.

• - Exhaust gas analyzer.

• - M. Kretschmar and S. Welsby (2005), Capacitive and Inductive Displacement Sensors, in Sensor Technology Handbook, J. Wilson editor, Newnes: Burlington, MA.

• - C. A. Grimes, E. C. Dickey, and M. V. Pishko (2006), Encyclopedia of Sensors (10-Volume Set), American Scientific Publishers. ISBN 1-58883-056-X.

• - Blaauw, F.J., Schenk, H.M., Jeronimus, B.F., van der Krieke, L., de Jonge, P., Aiello, M., Emerencia, A.C. (2016). Let’s get Physiqual – An intuitive and generic method to combine sensor technology with ecological momentary assessments. Journal of Biomedical Informatics, vol. 63, page 141–149.

• - Temperature sensor using the parallel port.

• - Sensors – General concepts. Detailed article about a wide variety of sensors.

• - Type of sensors. Concepts about elements and uses.

• - H2S sensors. Comparison: electrochemical and solid state sensors.

• - Sensors for home and building automation.

• - Flood sensor.

• - Piezoelectric sensors in music.

Contenido

• - Rango de medida: dominio") en la magnitud medida en el que puede aplicarse el sensor.

• - Precisión: es el error de medida máximo esperado.

• - Offset o desviación de cero: valor de la variable de salida cuando la variable de entrada es nula. Si el rango de medida no llega a valores nulos de la variable de entrada, habitualmente se establece otro punto de referencia para definir el offset. (down).

• - Linealidad o correlación lineal.

• - Sensibilidad "Sensibilidad (electrónica)") de un sensor: suponiendo que es de entrada a salida y la variación de la magnitud de entrada.

• - Resolución: mínima variación de la magnitud de entrada que puede detectarse a la salida.

• - Rapidez de respuesta: puede ser un tiempo fijo o depender de cuánto varíe la magnitud a medir. Depende de la capacidad del sistema para seguir las variaciones de la magnitud de entrada.

• - Derivas: son otras magnitudes, aparte de la medida como magnitud de entrada, que influyen en la variable de salida. Por ejemplo, pueden ser condiciones ambientales, como la humedad, la temperatura u otras como el envejecimiento (oxidación, desgaste, etc.) del sensor.

• - Repetitividad: error esperado al repetir varias veces la misma medida.

Un sensor es un tipo de transductor que transforma la magnitud que se quiere medir o controlar, en otra, que facilita su medida. Pueden ser de indicación directa (e.g. un termómetro de mercurio) o pueden estar conectados a un indicador (posiblemente a través de un convertidor analógico a digital, un computador y un visualizador) de modo que los valores detectados puedan ser leídos por un humano.

Por lo general, la señal de salida de estos sensores no es apta para su lectura directa y a veces tampoco para su procesado, por lo que se usa un circuito de acondicionamiento, por ejemplo un puente de Wheatstone, amplificadores y filtros electrónicos que adaptan la señal a los niveles apropiados para el resto de los circuitos.

Resolution and precision

The resolution of a sensor is the smallest change in the input magnitude that is seen in the output magnitude. However, precision is the maximum error expected in the measurement.

Resolution may be of lesser value than precision. For example, if when measuring a distance the resolution is 0.01 mm, but the precision is 1 mm, then variations in the measured distance of 0.01 mm can be seen, but it cannot be ensured that there is a measurement error of less than 1 mm. In most cases this excess resolution leads to an unnecessary excess in the cost of the system. However, in these systems, if the measurement error follows a normal or similar distribution, which is common in accidental errors, that is, non-systematic errors, the repeatability could be of a lower value than the precision.

Sensor resolution or measurement resolution is the smallest change that can be detected in the quantity being measured. The resolution of a sensor with digital output is usually the numerical resolution of the digital output. Resolution is related to the precision with which the measurement is made, but they are not the same. The accuracy of a sensor can be considerably worse than its resolution.

• - For example, distance resolution is the minimum distance that can be accurately measured by any distance measuring devices. In a time-of-flight camera, the range resolution is usually equal to the standard deviation (total noise) of the signal expressed in unit length.

• - The sensor may be sensitive to some extent to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment.

However, the precision cannot be a value lower than the resolution, since it cannot be ensured that the error in the measurement is less than the minimum variation in the input magnitude that can be observed in the output magnitude.

Un buen sensor obedece las siguientes reglas:.

• - es sensible a la propiedad medida.

• - es insensible a cualquier otra propiedad que pueda encontrarse en su aplicación, y.

• - no influye en la propiedad medida.

La mayoría de los sensores tienen una función de transferencia lineal. La sensibilidad "Sensibilidad (electrónica)") se define entonces como la relación entre la señal de salida y la propiedad medida. Por ejemplo, si un sensor mide la temperatura y tiene una salida de tensión, la sensibilidad es constante con las unidades [V/K]. La sensibilidad es la pendiente de la función de transferencia. La conversión de la salida eléctrica del sensor (por ejemplo, V) a las unidades de medida (por ejemplo, K) requiere dividir la salida eléctrica por la pendiente (o multiplicar por su recíproco). Además, con frecuencia hay que sumar o restar un desplazamiento. Por ejemplo, debe añadirse -40 a la salida si la salida de 0 V corresponde a una entrada de -40 C.

Para que una señal analógica de un sensor pueda procesarse o utilizarse en un equipo digital, es necesario convertirla en una señal digital, utilizando un conversor analógico-digital.

Sensor deviations

Since sensors cannot replicate an ideal transfer function, several types of deviations can occur that limit the sensor's accuracy:

• - Since the range of the output signal is always limited, the output signal will eventually reach a minimum or maximum when the measured property exceeds the limits. The "full scale range" defines the maximum and minimum values ​​of the measured property.

• - The sensitivity "Sensitivity (electronic)") may differ in practice from the specified value. This is called sensitivity error. This is an error in the slope of a linear transfer function.

• - If the output signal differs from the correct value by a constant, the sensor has an offset or bias error. This is an error in the y-intercept of a linear transfer function.

• - Nonlinearity is the deviation of a sensor's transfer function from a straight line transfer function. Typically, this is defined by the amount the output differs from ideal behavior over the full range of the sensor, often noted as a percentage of the full range.

• - The deviation caused by rapid changes of the measured property over time is a dynamic error "Dynamics (physics)"). This behavior is often described with a bode plot that shows the sensitivity error and phase shift as a function of the frequency of a periodic input signal.

• - If the output signal changes slowly regardless of the measured property, this is defined as drift&action=edit&redlink=1 "Drift (telecommunications) (not yet drafted)"). Long-term drift over months or years is caused by physical changes in the sensor.

• - Noise is a random deviation of the signal that varies with time.

• - A hysteresis error causes the output value to vary depending on the previous input values. If the output of a sensor is different depending on whether a specific input value was reached by increasing or decreasing the input, then the sensor has a hysteresis error.

• - If the sensor has a digital output, the output is essentially an approximation of the measured property. This error is also called digital quantization error.

• - If the signal is monitored digitally, the sampling rate can cause dynamic error, or if the input variable or added noise changes periodically at a frequency close to a multiple of the sampling rate, aliasing errors can occur.

• - The sensor may be sensitive to some extent to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment.

All these deviations can be classified as systematic errors or random errors. Sometimes systematic errors can be compensated for by some type of calibration strategy. Noise is a random error that can be reduced by signal processing, such as filtering, usually at the expense of the dynamic behavior of the sensor.

The following table indicates some types and examples of electronic sensors.

Some quantities can be calculated by measuring and calculating others, for example, the speed of a mobile phone can be calculated from the numerical integration of its acceleration. The mass of an object can be known by the gravitational force exerted on it compared to the gravitational force exerted on an object.

• - Heat detector.

• - Effector.

• - Insteon.

• - Passive infrared sensor.

• - Telecare.

• - X10.

• - Exhaust gas analyzer.

• - M. Kretschmar and S. Welsby (2005), Capacitive and Inductive Displacement Sensors, in Sensor Technology Handbook, J. Wilson editor, Newnes: Burlington, MA.

• - C. A. Grimes, E. C. Dickey, and M. V. Pishko (2006), Encyclopedia of Sensors (10-Volume Set), American Scientific Publishers. ISBN 1-58883-056-X.

• - Blaauw, F.J., Schenk, H.M., Jeronimus, B.F., van der Krieke, L., de Jonge, P., Aiello, M., Emerencia, A.C. (2016). Let’s get Physiqual – An intuitive and generic method to combine sensor technology with ecological momentary assessments. Journal of Biomedical Informatics, vol. 63, page 141–149.

• - Temperature sensor using the parallel port.

• - Sensors – General concepts. Detailed article about a wide variety of sensors.

• - Type of sensors. Concepts about elements and uses.

• - H2S sensors. Comparison: electrochemical and solid state sensors.

• - Sensors for home and building automation.

• - Flood sensor.

• - Piezoelectric sensors in music.