Tilt rotators can make a significant difference to the accuracy with which excavation tasks are completed. To measure and guide the minute movements made possible by this equipment, manufacturer SMP turned to AHM36 CANopen absolute encoders from SICK.
On an excavator, a tilt rotator can be added between the boom and the bucket to allow for more complex movements. It enables the operator to turn the bucket back and forth as well as change the level of incline. This provides support for precise trenching and slope pulling, and makes it possible to do earthworks accurately without having to move vehicle often during the work. Encoders are used here to measure the rotary position of the bucket in relation to the boom.
Coming from a background in excavator bucket production, SMP noticed an underserved market for these tilt rotators. The configuration and placement of the tilt rotator that SMP required demanded a highly tailored product from SICK. So too did the harsh environments in which it would be utilized. SMP needed a small, reliable encoder that could be installed in a small space and connected to a worm gear inside the tilt rotator. The encoder also had to be able to withstand high levels of shock and vibration, as well as temperatures as low as -40 °C. Moreover, it had to be able to function inside a casing that is filled with grease, meaning it needed its own protective housing.
The AHM36 CANopen absolute encoder was chosen for the task due to its high performance, high durability and small size. At just 36 mm, the AHM36 has a space-saving and cost-effective design, and is simple to install thanks to its rotatable male connector. Its stainless-steel design and IP69K enclosure rating (Inox versions) make it highly resilient to ambient influences. Meanwhile, its rugged, reliable, fully magnetic sensor system mean it can also be used in harsh environments such as the ones in which SMP tilt rotators operate.
The novel area of application presented room for improvement at first. This is a unique type of installation of SICK encoders on tilt rotators, and the solution has evolved over time. Thanks to close and continuous communication, SICK improved features in early iterations of these encoders that allowed some grease to make it past the protective layer.
SICK was very quick to improve the design to the customer needs. Engineers from SICK visited the site within a few weeks, in October 2023. The first new prototypes were sent to try out the very next month. Series delivery of the finalized product then started in early 2024. Rather than creating an entirely new product, the team adapted the current setup using existing hardware – a hybrid between IP69K and IP67. The housing located at the front of the worm gear where the flange and shaft connect needed the level of protection offered by the IP69K. Otherwise, the shape of the IP67 version with the necessary rotatable M12 connector was used. This means that the part has room to turn without crowding the other parts.
The site visits from SICK personnel and the open collaboration mean challenges are able to be met quickly. SMP also benefits from the CANopen interface of the absolute encoders. This allows excavator operators to see where the bucket is headed onscreen in the cabin immediately, allowing for precise digging.
SICK and SMP will continue to deepen their collaboration going forward. Meanwhile, this first use case for SICK absolute encoders in this specific environment opens up new potential for applications in mobile outdoor automation.
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