For small measuring ranges as they occur is robot grippers, classic, wound linear variable differential transformers (LVDTS) typically have an unfavorable ratio of size to measuring range. Our new approach combines the PCB technology for the sensor element with new evaluation electronics. This provides an open system with flexible implementation.
Linear variable differential transformers supply a position signal that depends on a linear offset of the core in the interior of the sensor. For this the core of the sensor is connected to the application via a coupling element. The result is that the mechanism is relatively large compared to the actual measuring range of the sensor. Our new approach based on an open sensor systems can provide a remedy, because a sensor element in PCB technology (FlexLVDT, PrintLVDT) is used instead of transformer windings. This allows cost-effective manufacturing, and at the same time it also allows effective reproducibility of the inductivity of the sensor. Instead of a core integrated in the sensor, which is coupled to the sensor mechanism, a ferromagnetic element from the application itself becomes the linear displaceable core.
Our new evaluation electronics dispenses with analysis of the amplitude, instead a phase evaluation via high-precision time measurement is used. This enables sensor sensitivity in the middle position as well. In addition, the position information is directly available in digital form, which means that analog-digital converters are no longer required. With these features, this innovative position sensor is robust relative to external disturbance variables and permits extremely high measurement repetition rates, dynamically adjustable resolutions, and retroactive adaptation in customer-specific applications.
In a joint project with Continental we have identified how FlexLVDT can be used as a new concept for a position sensor in future brake systems.