Piezoelectric Weight Sensing with Temperature Compensation
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Solution Overview
Problem
Existing weight sensing technologies, such as load cells using strain gauges, face challenges in power efficiency, maintenance requirements, and cost-effectiveness, particularly in large-scale deployments for inventory management systems.
Innovation Solution
The use of piezoelectric transducers, encapsulated for environmental protection and paired to compensate for temperature and humidity changes, which generate electric charges in response to mechanical stress, allowing for accurate weight measurement with reduced power consumption and lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If load cells using strain gauges are used for weight sensing, then weight measurement capability is achieved, but power consumption is high and maintenance is required
Solution Approach 1:
The patent replaces traditional mechanical strain gauge-based load cells with piezoelectric transducers that convert mechanical stress directly into electrical signals. This substitution eliminates the need for continuous power supply and complex electronics, achieving maintenance-free operation and ultra-low power consumption (nanoampere level) while maintaining weight measurement capability
Solution Approach 2:
The piezoelectric transducers generate their own electrical signal in response to mechanical stress without requiring external power. The system is inherently self-powered, where the weight being measured directly generates the measurement signal, eliminating the need for batteries, power wires, or active electronics that would require maintenance
2Use of energy by moving object
If piezoelectric transducers are used, then power consumption is reduced, but sensitivity to environmental changes (temperature, humidity) increases
Solution Approach 1:
The patent uses paired piezoelectric transducers where one experiences both weight and temperature effects while the other experiences only temperature effects. By mathematically processing the differential signals, the system changes the measurement parameter from absolute weight to weight-induced differential signal, effectively canceling temperature and humidity interference while maintaining environmental robustness
Solution Approach 2:
The patent introduces an intermediary mathematical processing step that acts as a signal filter. The differential measurement approach serves as an intermediary mechanism that separates the weight signal from environmental noise, allowing the system to operate reliably in varying environmental conditions without additional protective hardware
3Productivity
If large-scale deployment is implemented, then inventory management coverage is improved, but cost increases
Solution Approach 1:
The patent employs inexpensive piezoelectric transducers that can be easily manufactured and replaced. The simple construction using readily available piezoelectric materials (such as PZT ceramics) and basic encapsulation makes each unit cost-effective, enabling large-scale deployment across multiple shelves and locations without prohibitive costs
Solution Approach 2:
The patent divides the inventory management system into independent, modular sensing units that can be deployed individually on different shelves and locations. Each transducer operates independently, allowing scalable deployment where units can be added or removed based on specific inventory needs without affecting other units, thus managing overall system cost effectively
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
This solution enables a maintenance-free, cost-effective weight sensing system that can be deployed on a large scale, providing accurate weight change data and location information with minimal power consumption, suitable for inventory management in facilities like retail stores and warehouses.
Implementation Method 1
Each piezoelectric transducer comprises a piezoelectric material. A change in the mechanical stress on the piezoelectric material produces an electric charge.
Data Source
AI summary
An apparatus includes a platform or other accessory that is supported by one or more transducer assemblies using piezoelectric transducers. In one implementation, a saddle structure provides mechanical support to a platform while transferring force from a load onto a portion to which a pair of piezoelectric transducers are affixed. As a load on the saddle changes, the resulting change in strain on the portion produces signals from the piezoelectric transducers. In another implementation a beam provides mechanical support to a platform or other accessory. A pair of piezoelectric transducers are affixed near a strain concentrator, such as a hole in the beam, produce signals indicative of a change in load on the beam.