Build a non-contact sensor using the SG3Q technology designed to allow non-contact sensing of torque and angle in a custom and very compact design. Two modules are used to build a compact rotating torque/force sensor with an easy interface to any ¼, half, or full strain gauge bridge. It includes a lot of the optimizations in the SG3Q technology. And just to be clear: rotation is NOT required for the system to work.
Adding the third module to the stationary part allows the sensor to also detect the absolute angle between the rotating and stationary parts.
With a 1ms sample rate and adjustable filters, the sensor modules are useful for many applications. With the very compact size of only 7x17mm designing custom sensors for even quite challenging mechanical solutions is now an easy task.
Torque/force-sensing based on strain gauges is a very well-known and well-understood technology. This is easy to apply to any shape and type of metal.
Features
- Fast torque, angle, temperature, and rpm output
- Contactless, zero friction, and magnet-free
- No dead-band, fully linear positive and negative torque
- Low power consumption
- No residual torque effect, zero hysteresis
- Fast PCB design process
Non-Contact Strain Gauge Modules
Using the SG3Q technology in this compact module format makes it easy to make a 1/4, 1/2, or full-bridge strain gauge sensor contactless with an airgap of several millimeters. Perfect for rotating torque sensors and similar applications. Combining a wireless link for both power and data allows a very compact solution using inexpensive and easy to design PCB coils as “antennas” on both sides.
The technology combines the superior zero-point stability, resolution, and accuracy of a strain gauge based solution with low power consumption in a compact design that can be directly integrated into many systems.
Rotor Module – SG35
The rotating part of the sensor can be designed on a 4-layer PCB with a very simple design (2-layer PCB is possible without the angle sensing option). Let us help you do it, or do it yourself. The design process is quite simple and can even be done using free open-source layout software if needed (we have successfully used KiCAD layout software to design 20+ sensors).
Besides the rotor module (SG35) only one external capacitor is needed to match the PCB coil to the carrier frequency of the wireless link.
Stator Module – SG36
The stationary part of the sensor set is implemented using the SG36 module. In its minimal form this can be done on a 4-layer PCB with a simple PCB coil, a capacitor, and a connector to interface the sensor to a control or monitoring system.
Additional filtering and power conditioning may be added depending on the application and the requirements.
Angle Sensing Module – SG37
Adding the angle sensing module SG37 and another two PCB coils allow absolute angle sensing between the stationary part and the rotating part of the sensor system.
The three PCB coils can easily be implemented in two layers of the PCB.
Environmental Protection
To protect the strain gauge from humidity and light mechanical impact, a cover glue is recommended as a minimum. Consult the strain gauge supplier or bonding service provider for more information about this.
For best performance, the SG35/36/37 modules and all exposed strain gauge connections should be covered with a conformal coating or other sealing as changes in humidity may influence measured values. The best way to do this is to “bake” the circuit at 60C for 20 minutes first to remove humidity.
