Piezoelectric Drive Pulse Control for Low-Speed Precision Motion
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Solution Overview
Problem
Existing drive units, such as piezoelectric drives, have a limited operating range and efficiency in controlling the speed and position of passive elements, particularly in achieving a wide range of speeds and precise movements.
Innovation Solution
A method for operating a drive unit that involves modifying the driving signal by adjusting the excitation frequency, pulse shape, and omitting driving pulses to maintain energy transfer above a minimum threshold, allowing for quasi-continuous movement at low average speeds and precise control of speed and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the excitation frequency is reduced to achieve lower speeds, then the speed range is extended, but the energy transmitted by each driving pulse drops below the minimum threshold required for reliable operation
Solution Approach 1:
The patent applies dynamics by making the drive unit operate in two distinct operational modes that can be dynamically switched based on the required speed. At higher speeds, continuous pulsing is used, while at lower speeds, the system transitions to intermittent pulsing with longer intervals. This dynamic switching allows the system to adapt to different speed requirements while maintaining sufficient energy transmission in each pulse, thereby extending the usable speed range without compromising operational reliability.
Solution Approach 2:
The patent implements periodic action through intermittent pulsing at lower speeds, where driving pulses are applied in periodic intervals rather than continuously. This allows the resonator to come to rest between pulses, and the pre-stress force to reset the contact elements to their initial positions. By using periodic action with longer intervals between pulses, the system can operate at lower average speeds while ensuring each individual pulse still transmits sufficient energy to reliably drive the passive element.
2Speed
If driving pulses are repeatedly omitted to achieve lower average speeds, then the speed control range is improved, but the position precision and movement continuity deteriorate
Solution Approach 1:
The patent employs feedback mechanisms to monitor the position and speed of the passive element, allowing the control system to adjust the timing and frequency of driving pulses accordingly. This feedback ensures that even when pulses are omitted to reduce average speed, the system can maintain position precision by making precise adjustments based on real-time measurements, thereby compensating for the intermittent operation.
Solution Approach 2:
The pre-stress force applied to the contact elements serves as a preliminary action that ensures the passive element is properly positioned and ready for the next driving pulse. This preliminary force maintains contact and alignment between the active and passive elements during the intervals when driving pulses are omitted, ensuring that when the next pulse arrives, the system is ready for precise and reliable actuation, thereby maintaining position precision despite intermittent operation.
3Adaptability or versatility
If the excitation frequency is modified to extend the operating range, then the versatility is improved, but the energy efficiency and reliability of each driving pulse deteriorate
Solution Approach 1:
The patent applies dynamics by implementing two distinct operational modes that can be dynamically selected based on the required speed. In the first mode (higher speeds), continuous pulsing is used with standard excitation frequencies. In the second mode (lower speeds), the system switches to intermittent pulsing with modified excitation frequencies and longer intervals. This dynamic mode switching allows the system to extend its operating range while ensuring that in each mode, the excitation parameters are optimized to maintain sufficient energy transmission and operational reliability.
Solution Approach 2:
The patent utilizes parameter changes by modifying the excitation frequency and pulse timing parameters according to the operational mode. At lower speeds, the excitation frequency is reduced and pulses are spaced further apart, allowing the resonator to settle and the pre-stress force to reset the system. These parameter changes extend the operating range while maintaining reliability by ensuring each pulse operates within optimal energy transmission parameters, avoiding the reliability issues that would arise from using uniformly low-frequency pulsing across all speed ranges.
4Ease of operation
If driving pulses are omitted to achieve quasi-continuous movement at low speeds, then the ease of operation is improved, but the productivity and time efficiency deteriorate
Solution Approach 1:
The patent implements periodic action through intermittent pulsing that creates quasi-continuous movement at low speeds. By applying driving pulses in periodic intervals with longer durations and allowing the resonator to come to rest between pulses, the system achieves smooth, controlled movement that is easy to operate. The periodic application of energy, combined with the pre-stress force maintaining contact, ensures continuous propulsion without the need for complex control mechanisms, thereby improving ease of operation while accepting reduced productivity as a trade-off for low-speed precision control.
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
Enables a broader operating range and efficient control of speed and position of passive elements, enhancing the drive unit's performance in achieving desired speeds and positions with reduced energy consumption.
Implementation Method 1
the excitation means comprises a piezoelectric element; Upon excitation by an alternating voltage with an excitation frequency, the arms oscillate
Implementation Method 2
a resonator and at least one excitation means for exciting oscillations in the resonator
Data Source
Figure 1~3
Figure 4~7
Figure 8~11
AI summary
A method serves for operating a drive unit comprising an active element (1) having a resonator (2) and an excitation means (23) for exciting oscillations in the resonator (2) and thereby driving a passive element (4). The method comprises the steps of • driving the excitation means (23) with a driving signal, the driving signal being a periodic signal comprising driving pulses repeated with an excitation frequency; • depending on a control signal, modifying the driving signal by: o if the control signal is within a first range, modifying the excitation frequency or modifying the shape of the driving pulses, and o if the control signal is within a second range, repeatedly omitting driving pulses.