Forces and torque in a magnetically actuated harmonic motor

Abstract

The objective of this work is the calculation of forces and torque for a new type of motor, the harmonic motor, intended specifically for operation of brakes in vehicles. The motor offers the promise of eliminating a number of design limitations of existing electromechanical actuator systems. First, the motor eliminates the need for a gear set. This reduces the complexity of the package, which could result in a less expensive, more reliable, lighter and smaller overall package. Second, the harmonic motor inherently provides zero-force back-drivability and fails silent, greatly expanding the design space and simplifies the system fault analysis. Third, the motor has a low rotational inertia that could be used to improve the dynamic response of the system, improving both stopping distances and anti-lock braking control-ability. This work discusses a preliminary structure intended to show that the performance characteristics can be met and in particular that a specified torque can be obtained within given dimensional constraints. Simple analytical calculations based on magnetic circuits are first used to initiate linear and nonlinear finite element calculations of fields of forces.