Torque measurement using metamaterial tracks aligned by low-friction structure

A method of determining a torque applied to a rotatable shaft, the method comprising:

• providing at least one low-friction material between a first rotatable carrier structure coupled to the rotatable shaft and a second rotatable carrier structure coupled to the rotatable shaft;
• providing a first metamaterial track on the first rotatable carrier structure such that the first metamaterial track is configured to rotate with the first rotatable carrier structure;
• providing a second metamaterial track on the second rotatable carrier structure such that the second metamaterial track is configured to rotate with the second rotatable carrier structure, wherein the first metamaterial track and the second metamaterial track form a mutually coupled structure;
• applying the torque to the rotatable shaft to induce a rotational shift of the first metamaterial track relative to the second metamaterial track, wherein the at least one low-friction material is configured to provide a low-friction rotational shift between the first rotatable carrier structure and the second rotatable carrier structure such that a predetermined distance between the first metamaterial track and the second metamaterial track is constant during the rotational shift of the first rotatable carrier structure relative to the second rotatable carrier structure;
• transmitting an electromagnetic transmit signal toward the mutually coupled structure while the torque is applied to the rotational shaft;
• converting, by the mutually coupled structure, the electromagnetic transmit signal into an electromagnetic receive signal;
• evaluating the electromagnetic receive signal;
• and
• determining the torque applied to the rotatable shaft based on the evaluated electromagnetic receive signal.

A torque measurement system, comprising:

• a first rotatable carrier structure mechanically coupled to a rotational shaft and configured to rotate about a rotational axis in a rotation direction;
• a second rotatable carrier structure mechanically coupled to the rotational shaft and configured to rotate about the rotational axis in the rotation direction, wherein the second rotatable carrier structure is spaced apart from the first rotatable carrier structure;
• a first metamaterial track coupled to the first rotatable carrier structure and configured to co-rotate with the first rotatable carrier structure, wherein the first metamaterial track is arranged at least partially around the rotational axis;
• a second metamaterial track coupled to the second rotatable carrier structure and configured to co-rotate with the second rotatable carrier structure, wherein the second metamaterial track is arranged at least partially around the rotational axis,
• wherein the first metamaterial track and the second metamaterial track are spaced apart by a predetermined distance,
• wherein the first metamaterial track and the second metamaterial track are mutually coupled to each other by a torque-dependent coupling, thereby forming a mutually coupled structure, and
• wherein, in response to a torque applied to the rotational shaft, the first metamaterial track is configured to undergo a rotational shift relative to the second metamaterial track;
• and
• at least one structure arranged between the first rotatable carrier structure and the second rotatable carrier structure, wherein the at least one structure is mechanically not rigidly fixed to at least one of the first rotatable carrier structure or second rotatable carrier structure,
• wherein the at least one structure is configured to provide a low-friction rotational shift between the first rotatable carrier structure and the second rotatable carrier structure such that the predetermined distance is maintained constant during the rotational shift of the first rotatable carrier structure relative to the second rotatable carrier structure.