Motorized Spherical Probe Head for CMM Orientation

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Solution Overview

Problem

Conventional articulating probe heads in coordinate measuring machines (CMMs) are bulky, heavy, and costly due to multiple revolute joints and ancillary actuators, which affect precision and speed, and require complex wiring, limiting their ability to achieve precise and efficient orientation and measurement.

Innovation Solution

A motorized articulating probe head with a spherical joint that provides three degrees of freedom, using spherical ultrasonic actuators or brushless induction motors, and integrated encoders for continuous reorientation, along with a wireless link for communication, reducing size and weight while maintaining precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple revolute joints and ancillary actuators are used to enable probe orientation, then the probe head can achieve desired angular positions, but the bulk, weight, and cost increase

Engineering Contradiction:

Improveangular position adjustment capabilityVSAvoidprobe head weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent replaces traditional mechanical revolute joints with a spherical joint that provides three degrees of freedom. The spherical joint is actuated by only two actuators (azimuth and elevation) instead of multiple revolute joints with ancillary actuators, significantly reducing weight while maintaining full angular positioning capability. The spherical coordinate system naturally provides the required orientation freedom with minimal actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The orientation function is segmented into two independent rotational movements (azimuth and elevation) acting on a spherical joint, rather than using multiple coupled revolute joints. This segmentation allows each actuator to control one degree of freedom independently, reducing the total number of mechanical components and their associated weight.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple revolute joints are used for probe orientation, then angular positioning is achieved, but the device complexity increases

Engineering Contradiction:

Improveprobe orientation capabilityVSAvoidnumber of joints and actuators

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent substitutes a complex chain of revolute joints with a single spherical joint mechanism. The spherical joint inherently provides three degrees of freedom (two rotational angles and one radial position) with a simple spherical geometry, eliminating the need for multiple sequential revolute joints and their associated actuators, encoders, and control systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The spherical joint serves multiple functions simultaneously: it provides azimuth rotation, elevation rotation, and radial positioning capability all within a single mechanical component. This multi-functionality replaces what would otherwise require separate revolute joints and linear actuators, significantly simplifying the overall device architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If a longer chain of joints is used for probe orientation, then angular flexibility is improved, but wiring complexity increases due to obstacles that must be crossed by flexible connections or slip rings

Engineering Contradiction:

Improveangular flexibilityVSAvoidwiring complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the long chain of mechanical joints with a compact spherical joint system that achieves the same angular flexibility in a condensed configuration. This reduction in mechanical chain length directly reduces the complexity of wiring, as fewer flexible connections and slip rings are needed to traverse the joint chain, and the wiring path is significantly shortened.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables precise and efficient orientation of the measurement probe with reduced bulk and weight, enhancing measurement precision and speed, and eliminating the need for complex wiring, thus overcoming the limitations of conventional systems.

Implementation Method 1

spherical ultrasonic actuators

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

brushless induction motors

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10302407B2Motorized orientable head for measuring system

Publication Date: 2019.05.28 TESA SA(CH)

AI summary

An inclinable measuring head for use in a coordinate measuring machine or in another measure system. The inclinable head has a support element and a probe holder rotatably linked to the support element by a spherical joint that is capable of being rotated about three independent axes. The measuring head further includes a position encoder providing relative orientation of the probe holder with respect to the support element, and an actuator arranged for orienting the probe holder relative to the support element.