Sensor system and method for verifying the safety integrity of a sensor system
AssigneePilz GmbH & Co. KG
InventorsLambertus Pieter MONNEE, Armin GLASER
Life of this patent
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Abstract
A sensor system includes two analog sensors, each including a resistive sensing device that measures a physical variable and a Wheatstone bridge that generate an analog voltage signal in response to the physical variable. Each of the analog sensors supplies a measurement signal to a safety controller based on their respective analog voltage signals. The resistive sensing device of each analog sensor is connected to a switching path having parallel working and test paths with different resistances. The safety controller activates the test paths to alternately test the two resistive sensing devices and checks the plausibility of signal deviations in the measurement signals resulting from the tests.
Claims11
A sensor system, comprising:
- a first analog sensor including:
- a first resistive sensing device configured to measure a physical variable, and a first Wheatstone bridge configured to generate a first analog voltage signal in response to the physical variable, the first analog sensor supplying a first measurement signal based on the first analog voltage signal, wherein the first resistive sensing device is connected to a first switching path including a first working path and a first test path connected in parallel with the first working path, the first test path having different resistance characteristics than the first working path;
- a second analog sensor including:
- a second resistive sensing device configured to measure the physical variable, and a second Wheatstone bridge configured to generate a second analog voltage signal in response to the physical variable, the second analog sensor supplying a second measurement signal based on the second analog voltage signal, wherein the second resistive sensing device is connected to a second switching path including a second working path and a second test path connected in parallel with the second working path, the second test path having different resistance characteristics than the second working path;
- and
- a safety controller connected to the first and second analog sensors to receive the first and second measurement signals, wherein the safety controller is configured to:
- activate the first test path to test the first resistive sensing device, generate a first test signal, and detect a first signal deviation of the first measurement signal in response to the first test signal;
- activate the second test path to test the second resistive sensing device, generate a second test signal, and detect a second signal deviation of the second measurement signal in response to the second test signal;
- and
- check plausibility of the first and second signal deviations.
Dependencies are inferred from the claim text.