Motorized Coordinate Measuring Device Cable Pulley Actuation
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Solution Overview
Problem
Existing coordinate measuring devices face challenges in achieving high precision due to multiple components and sensitivity to temperature variations, while also being bulky and heavy, and there is a need for a lightweight yet precise solution.
Innovation Solution
A coordinate measuring device utilizing cable and pulley mechanisms driven by electrical motors, with a complex routing of cables to accommodate displacement without affecting secondary elements, allowing for precise positioning of a probe along orthogonal axes and rotation of a base component, powered by a data processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a probe is mounted on an articulated, multi-axis measurement arm with multiple moving parts, then the device is more flexible and easier to operate, but high precision is seldom achieved and the device is sensitive to temperature variations
Solution Approach 1:
The patent replaces the traditional mechanical articulated arm with a robotic manipulator system controlled by multiple independent motors. Each motor controls a specific degree of freedom through cable-pulley mechanisms, eliminating the mechanical linkages and joints that cause precision loss and temperature sensitivity. The robotic system uses direct motor control with encoders to achieve precise positioning without mechanical transmission errors.
2Ease of operation
If a probe is mounted on an articulated, multi-axis measurement arm, then the device is easier to operate, but the device becomes bulkier and heavier
Solution Approach 1:
The patent eliminates heavy mechanical linkages, bearings, and motors mounted on moving components by using a centralized motor system with cable-pulley actuation. The motors remain stationary in the base, and cables transmit force to the moving parts, significantly reducing the weight of the manipulator arm and probe assembly while maintaining full six-degree-of-freedom motion capability.
3Adaptability or versatility
If multiple components and moving parts are used in the coordinate measuring machine, then the device is more versatile, but high precision is seldom achieved
Solution Approach 1:
The patent replaces mechanical components with a robotic system that uses cable-pulley mechanisms actuated by stationary motors. Each of the six degrees of freedom is controlled by an independent motor, with cables routed through pulleys to achieve the desired motion. This eliminates mechanical play, backlash, and cumulative positioning errors while maintaining full versatility for various measurement tasks.
Solution Approach 2:
The patent introduces cable-pulley mechanisms as intermediaries between the stationary motors and the moving manipulator components. The cables transmit force and motion control from the base-mounted motors to the various links and the probe, enabling precise control without direct mechanical connections between moving parts.
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 a lightweight, portable device with high precision, achieving up to 5 micron far-range accuracy and 2 micron near-range accuracy, while maintaining a compact size and reducing weight, allowing for accurate coordinate measurement of workpieces.
Implementation Method 1
cable and pulley mechanisms driven by electrical motors
Data Source
Figure 1
Figure 2~3
AI summary
A coordinate measuring device (10) comprises a housing (12) rotatively supported on a base (11) and mounting a vertical pillar (13) along which rides a carriage (14) engaged by a horizontally translating arm (15). A turret (18,19) at each end of the arm houses a rotating body (20,21) connected to a probe (22,23). The rotation of the base, the vertical movement of the carriage, the horizontal movement of the arm and the rotation of the probes are driven by motors (27,28,29,30) in the housing. The rotation of the motors are transmitted by a cable and pulley assembly to the arm and carriage. The cable (43) controlling the transversal movement of the arm has its opposite ends attached to the opposite extremity (16,17) of the arm, and is run respectively up and down the portion of the pillar above and below the carriage in order to maintain constant lengths and tension of the cables as the carriage moves up and down the pillar. The rotation of the probes and that of the base are coordinated to keep the probes at a constant angle in relation to the measured surface.