Height-Adjustable Worktable Obstacle Detection via Strain Gauges

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Solution Overview

Problem

Existing height-adjustable work tables face challenges in accurately detecting obstacles along the adjustment path due to varying friction conditions, which can lead to improper motor control and potential damage.

Innovation Solution

The integration of strain gauges on load-bearing parts of the frame allows for precise monitoring of table loads, enabling accurate detection of obstacles and reversing the motor direction or switching it off to prevent impact, regardless of friction conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If motor load monitoring is used to detect obstacles, then the control system can respond to potential obstacles, but the detection accuracy is insufficient due to varying friction conditions in the actuator and guide areas

Engineering Contradiction:
Improveobstacle detection accuracyVSAvoiddetection reliability under varying friction conditions
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A force transducer is introduced as an intermediary component between the actuator and the adjustment part to directly measure the force required to move the adjustment part. This mediator provides accurate obstacle detection by measuring actual resistance forces, eliminating the influence of varying friction conditions that plague direct motor load monitoring.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces indirect mechanical inference (monitoring motor load to infer obstacles) with direct mechanical measurement (using a force transducer to directly measure resistance forces). This substitution transitions from inferential detection to direct measurement, significantly improving detection accuracy and reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a force transducer is integrated into the adjustment part to directly measure load, then obstacle detection accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improveload measurement accuracyVSAvoidstructural complexity of adjustment mechanism
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The force transducer is merged with existing structural components of the adjustment mechanism, such as integrating it into the telescopic leg or support structure. This combining approach allows the force measurement function to be added without creating entirely separate measurement systems, thereby reducing the overall complexity increase.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The force transducer serves multiple functions: it measures obstacles, monitors table top position, and provides feedback for control systems. This multi-functionality justifies the added complexity by providing several measurement capabilities from a single integrated component rather than requiring separate sensors for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If multiple load-bearing parts are equipped with strain gauges to improve load monitoring, then the precision of load condition determination is enhanced, but the manufacturing complexity increases

Engineering Contradiction:
Improveload condition monitoring precisionVSAvoidmanufacturing complexity of frame structure
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The frame is segmented into multiple load-bearing parts, each equipped with its own strain gauge or force transducer. This segmentation allows independent measurement at different locations, providing comprehensive load monitoring. Each segment can be manufactured and calibrated separately, simplifying the overall manufacturing process despite the increased number of components.

Inventive Principle:
Principle #1Segmentation

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 ensures improved safety by accurately detecting load changes and preventing impermissible forces on the work table, allowing for precise control of the motor to avoid obstacles effectively.

Implementation Method 1

At least one load-bearing part (13) of the frame (2) is provided with a strain gauge (12), by which the load on the respective table (1) or a change in the load can be detected

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP1704797B1Worktable
Publication Date: 2011.08.03 LOGICDATA ELECTRONICS & SOFTWARE ENTWICKLUNGS
  • EP1704797B1 patent drawingFigure 1
  • EP1704797B1 patent drawingFigure 2~3

AI summary

The work table has a height adjustable frame (2) with adjustment actuators (5) operated by electric motors (4) with a control (6). At least one load carrying section of the frame (2) has an extension measuring strip which controls the extension adjustment via the motor in dependence on the applied load.