Coffee Grinder Weight Correction Using Consecutive Error Feedback
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Solution Overview
Problem
Existing coffee grinders suffer from inaccuracies in dispensing coffee weight due to variable time-of-flight, which is influenced by grain size and mechanical/electronic factors, and existing correction methods are unreliable, especially when lumps occur.
Innovation Solution
A coffee grinder with a correction system that only corrects the time-of-flight weight after two consecutive errors and uses a correction factor proportional to the error magnitude, minimizing inaccuracies and allowing for refills if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the grinder unit is stopped in advance to account for time-of-flight, then the coffee weight accuracy is improved, but the dosing precision deteriorates due to variable time-of-flight depending on grain size and mechanical structure
Solution Approach 1:
The control unit continuously monitors the actual coffee weight dispensed and compares it with the target weight. Based on this feedback, the control unit automatically adjusts the time-of-flight compensation value for subsequent dispensing operations, eliminating the need for manual calibration and adapting to variations in coffee grain size and grinder mechanics
Solution Approach 2:
The system dynamically changes the time-of-flight compensation parameter based on actual dispensing results. The control unit modifies this parameter in real-time to optimize dosing precision, transforming a static fixed value into a dynamic adaptive value that responds to actual system performance
2Reliability
If the average of multiple weighing operations is used to correct time-of-flight weight, then the correction reliability is improved, but the measurement precision deteriorates when lumps occur during dispensing
Solution Approach 1:
The control unit identifies and excludes abnormal data points (caused by lumps or other anomalies) from the averaging calculation. By extracting only valid measurements from the dataset, the system maintains correction reliability while preserving measurement precision, avoiding the contamination that would occur if all measurements including outliers were averaged
3Manufacturing precision
If the time-of-flight weight is increased by excess to ensure lower dispensed weight, then the dosing accuracy is improved, but the productivity deteriorates due to frequent refills
Solution Approach 1:
The control unit uses feedback from actual dispensing results to optimize the time-of-flight compensation value, finding the precise balance point that achieves accurate dosing without excessive compensation. This eliminates the need for frequent refills while maintaining dosing accuracy, thereby improving productivity
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
Ensures accurate and reliable coffee weight dispensing by minimizing errors and adjusting for variations in grain size and mechanical structure, while being easy to use and implement.
Implementation Method 1
a load cell (6) connected to the support (4) to weigh the coffee powder in the filter holder (5)
Implementation Method 2
When the grinder unit of the coffee grinder is stopped, the grinder unit continues to rotate due to inertia and thus a small amount of ground coffee continues to be dispensed from the dispensing duct
Data Source
AI summary
A coffee grinder has a coffee weight correction system that provides for comparing an error given by a difference between a measured weight measured by a load cell and a set weight set by a user with four threshold weights. If for two consecutive weighing operations the error is higher than the second weight threshold or lower than the first weight threshold, a correction algorithm makes a correction by setting a correction factor proportional to the modulus of the error of the last weighing operation.