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Revolution in E-Bike Torque Sensor Technology Arriving?

Sales & Trends

Revolution in E-Bike Torque Sensor Technology Arriving?
Sensor specialist Trafag ‘E-bike performance as perceived by cyclist depends crucially on sensor signal quality.’ – Photos Trafag

UNTERENSINGEN, Germany – The company is a leading international supplier of high-quality sensors and monitoring instruments for ships, trains, large engines, water treatment and gas density monitoring. At last month Eurobike this company – Trafag GmbH – presented itself for the first time and gauged the interest in its Magnetic Sense sensor technology. A technology that at first glance can mean a revolution for what is now widely used within electric bicycles.

Sensors that are currently widely used in electric bicycles form the basis of this category’s current sales success. In particular as this success is based on the fact that e-bikes are legally regarded as normal bicycles. This is caused by the fact that by simply moving the pedals, instead of a throttle, the e-bike is moving forward. Sensors are therefore a vital part of e-bikes. However, are sensors that measure distortions in for instance drive shafts and with that the torque to subsequently match the degree of motor support, still of this time? Can that be improved? Trafag AG with its Magnetic Sense technology claims that this is possible.

Measurement error

What the sensor specialist claims is that “The performance of an e-bike perceived by the driver depends crucially on the quality of the control and thus on the quality of the sensor signals. The detection of the torque is here a key component of the input to the control. The largest error contribution of a torque measurement on a rotating shaft in the e-bike is the measurement error caused by the rotating shaft – short RSN (Rotational Signal Nonuniformity). This measurement error is due to inhomogeneities in the wave structure that affect the sensor signal when the shaft rotates. By an additional integration of an angle sensor to the torque sensor, a location-dependent compensation of this RSN can be carried out, which contributes decisively to a very small measurement error of the torque sensor and thus to driving behavior. In addition, this angle information may be provided to the driver as a pedal crank angle and so forth. High performance athletes serve to gather information as the tread homogeneity of both legs varies over the orbital angle. The integration of the torque sensors from Magnetic Sense into customer projects can be implemented relatively easily due to the modular design, and it is possible to address various interface requirements with regard to the mechanical and electrical design. The modular platform, including the electrical interface options, contributes to the rapid implementation in samples and market introduction.”

For further technical Magnetic Sense guidelines, see the pdf at the bottom of this webpage.

Magnetic Sense technology advantages

Sensor specialist Trafag AG claims that its sensor technology for e-bikes offers the following advantages compared to the currently commonly used torque sensors:

  • Contactless measuring principle
  • Insensitive to mechanical overload
  • Digital literate output signal
  • Robust against magnetic and electrical interference fields
  • No mechanical or magnetic machining of the measuring point necessary
  • No specific requirements for the shaft’s material
  • Modular kit that can be applied to custom requirement

Magnetic Sense sensors are marketed by Magnetic Sense GmbH which is a 100 percent subsidiary of Trafag AG. Magnetic Sense GmbH deals exclusively with magnetic inductive sensors (torque sensors, force sensors and angle sensors).

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