Scanning Probe with Strain-Sensing Bendable Members
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Solution Overview
Problem
Existing scanning probes for coordinate positioning apparatuses, such as machine tools, have limited deflection ranges and are often costly due to complex spring and transducer arrangements, making them unsuitable for general-purpose measurement applications.
Innovation Solution
A scanning probe design featuring a strain-sensing structure with an inner and outer portion connected by curved bendable members, allowing for increased deflection range without increasing the probe's size, and incorporating strain-sensing elements to measure bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a complex spring and capacitive transducer arrangement is used to achieve large deflection range, then the scanning capability is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces the complex mechanical spring and capacitive transducer system with a strain-sensing structure that uses strain gauges to detect stylus deflection. This substitution maintains the ability to measure large deflections while significantly reducing device complexity and cost. The strain gauges are mounted on a deformable element that flexes with stylus movement, providing direct mechanical-to-electrical signal conversion without complex intermediate mechanisms.
Solution Approach 2:
The patent changes the measurement parameter from capacitive displacement sensing to strain-based detection. By mounting strain gauges on a deformable element, the system directly measures the strain produced by stylus deflection, enabling large deflection ranges to be measured with simpler, more cost-effective components while maintaining scanning capability.
2Device complexity
If a simple strain sensor is used for touch trigger measurement, then the device complexity is reduced, but the deflection range is limited
Solution Approach 1:
The patent employs a curved or arc-shaped deformable element instead of a straight rigid structure. This curvature allows the element to flex through larger angles and displacements while remaining within its elastic range, thereby extending the measurable deflection range without increasing device complexity. The strain gauges are positioned to detect strain along this curved path, capturing the full range of motion.
Solution Approach 2:
The patent transitions from a static rigid structure to a dynamic deformable element that can adapt its shape during measurement. The deformable element flexes dynamically in response to stylus deflection, enabling the system to accommodate both small touch trigger signals and large scanning deflections within the same structure, thus extending the effective deflection range without adding complexity.
3Ease of operation
If the probe size is kept compact, then the ease of operation is improved, but the deflection range is constrained
Solution Approach 1:
The patent integrates the strain gauges directly onto the deformable element itself, nesting the sensing function within the structural component. This eliminates the need for separate transducer housings and mounting mechanisms, allowing the system to achieve large deflection ranges within a compact probe form factor. The strain-sensing structure is embedded within the probe body, maximizing space efficiency.
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 design achieves a significantly expanded working range of deflection, enabling the scanning probe to function both as a touch trigger probe and a scanning probe, while maintaining robustness and cost-effectiveness.
Implementation Method 1
the plurality of bendable members comprising at least one strain-sensing element
Data Source
AI summary
A scanning probe for a coordinate positioning apparatus, such as a machine tool, is described that includes a probe body connected to a stylus holder by a strain-sensing structure. The strain-sensing structure has an inner portion connected to an outer portion by a plurality of bendable members. A proximal end of each bendable member is attached to the inner portion and a distal end of each bendable member being attached to the outer portion. The inner and outer portions are centred on a central axis and the plurality of bendable members include at least one strain-sensing element. The proximal and distal ends of each bendable member are located at different angles about the central axis. Such an arrangement enables both scanning and touch trigger measurements to be acquired.