Optical rotary torque sensors for low torque and high bandwidth

These devices provide precise, dynamic measurement of rotary and static torque from 10mNm to 100Nm, with bandwidths of up to 50kHz.

The ORT 230/240 series features improved electronics that enhance resolution, frequency response, reduce sensor current consumption, and allow faster digital data throughput. Its high-speed performance is supported by a low inertia design, as the electronics are not fixed to the shaft. The non-contact operation ensures a long operational life, complemented by Sensor Technology's lifetime warranty, with consistent accuracy. The optical design also provides strong noise immunity.

The ORT 230 series offers fixed voltage or current analogue outputs – one for torque and one for either speed or power. The ORT 240 model includes two user-selectable analogue outputs – one for torque and the other for speed, power, or peak torque. It also offers digital outputs, including RS232, CANbus, and USB, allowing integration with modern instrumentation and laptops. The ORT 240 can connect up to 10 transducers via USB, and includes software for configuring transducer variables.

Both models feature self-diagnostics to report if torque or speed ratings, or calibration dates, have been exceeded. Integrated sensors monitor shaft temperature, improving compensation and accuracy. Additionally, the device provides a simple 'sensor status' output.

Sensor Technology’s TorqView software complements the hardware by offering an easy-to-use torque monitoring package for Windows PCs, with features for real-time chart plotting and data recording. It is compatible with Matlab and Excel, and LabVIEW VIs are available for custom process control applications. DLLs are also available for users interested in creating their own software.

These sensors expand Sensor Technology's torque monitoring range, providing an alternative solution when low torque or high bandwidth is required, where the TorqSense range may not be suitable.

Optical rotary torque sensors utilise a pair of gratings attached a short distance apart on a strain-sensitive shaft to modulate a light source. When torque is applied, a slight twist in the shaft alters the grating alignment, changing the light transmission to a detector. This method allows the transducer to detect torque in both directions, offering a fast mechanical and electrical response, low inertia, and no need for brushes or complex electronics.

The lack of brush gear enables high-speed operation, with a continuous rating of up to 30,000rpm as standard, with potential for higher speeds depending on shaft size. The torque shaft is designed with low compliance, exhibiting maximum torsion deflections of ½° for smaller transducers and ¼° for larger transducers at full scale deflection. Full-scale torque can be specified within the range of 10mNm to 100Nm.