An absolute encoder sends a position value of the shaft for positioning, the single-turn position, in a production or packaging machine, for example. If you want to record the absolute value beyond one revolution, the number of revolutions is recorded in addition to the single-turn position. This is referred to as a multi-turn encoder. The position information is usually sent to a controller using a protocol via an intelligent interface (e.g. PROFINET, EtherCAT, CAN).
The rotary motion from the application makes mechanical energy available to the encoder. If it is possible to convert this into sufficient electrical energy so as to write the number of revolutions in an electrical metre, then, although this is not the invention of a perpetual-motion machine, it does constitute an energy self-sufficient metre for the revolution count. A dynamo does not work, because even the smallest rotations can occur at low speed.
Functional principle of EnDra® Multi-turn Technology
A Wiegand wire consists of a hard magnetic sleeve and a soft magnetic core. The absolute position per revolution (single-turn) is measured with a magnet on the rotating shaft and four Hall sensors. If the field of the magnet moves along the Wiegand wire by rotating the shaft, the soft magnetic core is forced to follow the field, constrained by the hard magnetic sleeve.
An increasingly-greater field difference is created in the wire (for example, when tensioning an arc). As soon as the external field reaches the coercive field strength of the sleeve, the sleeve is demagnetised, and the built-up voltage of the core suddenly jumps over.
This pulse, which is independent of the speed, is generated twice per revolution and converted into electrical pulses using a coil. These pulses generate enough energy to operate a low energy FRAM memory and also provide information on the number of revolutions.
No additional external energy is needed for this revolution count. If an external voltage is applied once again, an intelligent microcontroller calculates the correct value from the position, and the number of revolutions then sends this value to the controller.
EnDra® multi-turn technology has the potential to trigger creative destruction. It can and indeed - according to Robert Wachendorff - “will” completely change the market. This is supported by the assertions such as the following:
- In Germany alone, this would probably eliminate the need to use more than 250,000 batteries and drives each year. The environmental protection aspect alone guides us along this direction.
- If the market fully buys into and embraces this new technology - obsolete technologies using drives and battery will be completely replaced.
- The lower material and production costs mean that completely new areas of application can be opened up.
- The limitations of outdated technologies using drives or batteries (e.g. temperature sensitivity, large space demands, maintenance requirements, high environmental pollution and onerous disposal requirements) are continuously opening up new markets, for example, in the fields of wind energy, medical technology, lift technology, mobile working machines and plant and machine construction.
- Drive manufacturers will experience very significant declines in sales in the multi-turn encoder segment.
EnDra® multi-turn technology opens up completely new areas of application for absolute encoders, for example, in lift construction, mobile machinery, medical technology, alternative power generation and in machine and apparatus construction.
EnDra® is the innovative milestone for miniaturisation, freedom from maintenance and for environmental friendliness in absolute multi-turn encoders, which will trigger this “creative destruction
The advantages and thus the benefits resulting from this technology are enormous for the user, machine manufacturer and plant operator.
Environmentally friendly, maintenance-free, no need for disposal, and lower administrative costs.
Wear-free and maintenance-free.
Smaller Design & Low Weight
Less space required means new application possibilities.
Lower susceptibility to failure.