Virtual Resistive Load Feedback Circuit for Piezoelectric Actuator Hysteresis
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Solution Overview
Problem
Piezoelectric actuators exhibit nonlinearity, hysteresis, and creepage issues due to the non-linear displacement response to applied voltage, which reduces the precision of control in micro- or nano-positioning applications.
Innovation Solution
A power driving circuit with a hysteresis compensation circuit, including a summing circuit and a capacitance dividing circuit, is used to generate a feedback signal based on voltage and current monitor signals, allowing for precise control of piezoelectric actuators by approximating a virtual resistive load across the actuator, thereby correcting hysteresis errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage monitoring and current monitoring are performed separately, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines voltage monitoring and current monitoring into a single integrated circuit block that processes both signals simultaneously. The voltage monitor circuit and current monitor circuit share common components and processing pathways, merging two separate measurement functions into one unified structure that reduces overall device complexity while maintaining measurement precision for both parameters.
2Manufacturing precision
If hysteresis compensation is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements hysteresis compensation by feeding back the difference between the actual output signal and the expected output signal (derived from the input signal) to adjust the driving signal. This feedback mechanism continuously corrects for hysteresis effects, improving manufacturing precision while managing device complexity through efficient feedback loop design.
Solution Approach 2:
The system pre-calculates the expected output signal based on the input signal and stored hysteresis characteristics before applying the driving signal to the piezoelectric actuator. This preliminary action allows the system to anticipate and compensate for hysteresis effects in advance, improving precision without requiring complex real-time correction mechanisms.
3Reliability
If feedback loop with virtual resistive load is used, then reliability is improved, but use of energy increases
Solution Approach 1:
The patent employs a virtual resistive load that dynamically adjusts its equivalent resistance parameter based on operating conditions to optimize the feedback loop performance. By changing the effective resistance parameter rather than using a fixed physical resistor, the system improves reliability through better compensation accuracy while minimizing energy consumption by adapting to different operational states.
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 provides more precise control and improved accuracy of piezoelectric actuators by reducing hysteresis and drift errors, while minimizing power dissipation and device constraints, enabling more precise movement control.
Implementation Method 1
The piezoelectric effect is the linear displacement of a piezoelectric material, usually a type of crystal or ceramic material, when an electrical signal is applied to the material.
Data Source
AI summary
A virtual resistive load feedback circuit for driving a piezoelectric actuator is provided that accounts for a hysteresis error and drift within the movement of the actuator. The circuit may include a voltage divider and charge divider. A voltage monitor signal corresponding to a voltage of a driver signal and a current monitor signal corresponding to a current provided to the amplifier are combined by an operational amplifier and include electrical characteristics of the actuator such that the circuit approximates a virtual load across the actuator. A feedback portion of the operational amplifier may include a resistor and capacitor connected in parallel to provide the voltage and charge divide functions. The use of the virtual resistive circuit allows for the piezoelectric actuator to be ground referenced, with no external components connected directly to the actuator while gaining the feedback effect to counter the hysteresis and drifts errors of the actuator.