Methods and apparatus for flexure-based torque sensor in a bicycle

摘要

In exemplary implementations, a bicycle has “power pedaling”, in which a rider's pedaling efforts are augmented by an electric motor. The rider can control the motor simply by pedaling. It is desirable that the motor torque not exceed the rider torque; otherwise the motor overpowers the rider. A radial flexure is part of the drivetrain that transmits torque from the rider to the back wheel. One part of the flexure is connected to the back wheel casing; another part of the flexure is connected to the freewheel. If motor velocity exceeds rider velocity, this causes the flexure to elastically deform. Two sensors measure the deformation, which is equal to the difference between the angular displacements of the casing and freewheel, respectively. A PD controller seeks to make this difference equal to zero, by controlling voltage levels in the motor (and thus controlling the torque contributed by the motor).

主权项

1. Apparatus comprising, in combination:
(a) a radial flexure; (b) one or more sensors; and (c) a controller; wherein
(i) the flexure is part of a drivetrain, which drivetrain comprises the radial flexure, pedals of a bicycle, and a component that is directly coupled to the flexure, and which drivetrain is configured to transmit power from the pedals to a wheel of the bicycle;(ii) the flexure is configured to undergo elastic deformation due to a difference between rotational displacement of the wheel and of the component, respectively;(iii) the one or more sensors are configured to measure the elastic deformation; and(iv) the controller is configured to seek to cause the difference between rotational displacement to be a constant, by controlling torque imparted by a motor to the wheel.