Piezoelectric Motor Coupling with Shape Memory Alloy
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Solution Overview
Problem
Piezoelectric motors face challenges in efficiently controlling motion and positioning of moveable bodies due to rapid wear during the initial run-in period, leading to instability in frictional coupling surfaces, and existing solutions do not provide adequate control over coupling forces for efficient engagement and disengagement.
Innovation Solution
A coupling apparatus utilizing shape memory components, such as shape memory alloys (SMAs), to control the coupling force between the piezoelectric motor and the moveable body, allowing for adjustable resilient forces to engage or disengage the motor, thereby managing wear and improving control over motion and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the piezoelectric motor is resiliently pressed to the moveable body to provide coupling force, then motion transmission efficiency is improved, but wear during the initial run-in period increases rapidly
Solution Approach 1:
The patent applies a compliant coupling mechanism that dynamically adapts the coupling force between the piezoelectric motor and moveable body. The compliant element allows the coupling force to vary during operation, providing higher force during run-in to ensure stable motion transmission, then reducing force as surfaces wear in, thereby resolving the contradiction between maintaining efficient motion transmission and reducing excessive wear during the initial period.
2Measurement precision
If the coupling force is increased to stabilize motion control, then positioning precision is improved, but the moveable body becomes difficult to move manually
Solution Approach 1:
The compliant coupling mechanism enables dynamic adjustment of coupling stiffness. During automated operation, the system maintains high coupling force for precise positioning control. During manual adjustment, the compliant element allows the coupling force to decrease, enabling easy manual movement of the moveable body without compromising positioning precision during automated modes.
Solution Approach 2:
The patent changes the mechanical impedance parameter of the coupling system by introducing a compliant element with specific stiffness characteristics. This allows the system to exhibit different effective coupling forces depending on the operating mode, achieving both precise automated control and easy manual adjustability by exploiting the non-linear mechanical properties of the compliant coupling mechanism.
3Stability of the object's composition
If the piezoelectric motor is continuously engaged to maintain positioning, then positioning stability is improved, but wear of the coupling surfaces accelerates
Solution Approach 1:
The compliant coupling mechanism introduces periodic variation in the contact force between the motor and moveable body during operation. This periodic action allows the coupling surfaces to experience varying stress levels, maintaining stable positioning through the compliance mechanism while reducing continuous high-stress contact that would accelerate wear, thereby resolving the contradiction between positioning stability and wear reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient control of motion and positioning by adjusting coupling forces, reducing wear and allowing for easy manual or motor-assisted movement of the moveable body without damaging stress on the piezoelectric motor, while maintaining contact and stability.
Implementation Method 1
A coupling apparatus utilizing shape memory components, such as shape memory alloys (SMAs), to control the coupling force between the piezoelectric motor and the moveable body
Implementation Method 2
A piezoelectric motor uses a piezoelectric vibrator to transduce electrical energy into kinetic energy that the motor transmits to a moveable body
Implementation Method 3
A suitable elastic element, generally a coil or leaf spring, provides a 'coupling force' that resiliently presses the motor coupling surface to the contact surface of the body
Implementation Method 4
Motion is transmitted from the vibrating coupling surface to move the body by frictional forces between the coupling surface and the surface region, hereinafter a 'contact surface', of the body to which the coupling surface is pressed
Data Source
AI summary
A mirror system comprising: a mirror; at least one piezoelectric motor having a coupling surface for coupling the motor to a moveable body; at least one spherical contact surface coupled to the mirror; and a motor mounting frame that holds a piezoelectric motor of the at least one piezoelectric motor and presses the piezoelectric motor coupling surface to a contact surface of the spherical contact surface; wherein the motor is controllable to apply force to the contact surface that rotates the mirror.