Motorized Measurement Arm Holding Torque for Repeatable Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motorized measurement arm apparatuses for machine tools suffer from repeatability issues in their operative position, particularly under conditions of machine vibrations or when carrying heavy sensors, leading to measurement uncertainty.
Innovation Solution
A motorized measurement arm apparatus with a mechanical stop arrangement maintained by a motor's holding torque, where the motor remains energized after reaching the operative position to ensure consistent engagement, reducing the impact of vibrations and improving positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical stop arrangement with spring-based detent mechanism is used to define the operative position, then the apparatus is compact and robust, but the repeatability of the operative position degrades under machine vibrations or when carrying heavy sensors
Solution Approach 1:
The patent replaces the purely mechanical spring-based detent mechanism with an electromechanical system. A motor (electromagnetic actuator) is used to actively position and hold the measurement arm at the operative position, substituting passive mechanical spring forces with controlled electromagnetic forces. This allows for more precise and stable positioning that is not susceptible to the same vibration and load issues affecting mechanical springs.
Solution Approach 2:
The motorized system provides active self-correction and self-holding capability. The motor continuously maintains the operative position through controlled electromagnetic torque, automatically compensating for disturbances such as vibrations or changes in sensor weight without requiring external intervention or complex mechanical adjustment mechanisms.
2Stability of the object's composition
If tension springs are used to maintain engagement of the mechanical stop, then the arm member can be held in the operative position, but the apparatus becomes less compact and robust
Solution Approach 1:
The patent replaces the complex mechanical spring arrangement with a simpler electromechanical motorized system. The motor provides direct actuation and holding capability, eliminating the need for multiple tension springs and their associated mounting mechanisms. This reduces mechanical complexity while improving engagement stability through active electromagnetic control.
3Reliability
If the motor is deactivat ed after reaching the operative position, then energy consumption is reduced, but the engagement of the mechanical stop is not maintained under vibration or load
Solution Approach 1:
The motor operates in periodic cycles: it is activated to move the arm to the operative position, then deactivated or placed in a low-power holding mode once positioned. This periodic activation pattern reduces energy consumption while maintaining positioning reliability, as the motor only consumes significant power during movement phases rather than continuously.
Solution Approach 2:
The system uses feedback control to determine when the operative position has been reached and when the motor can be deactivated. Sensors or position detection mechanisms provide feedback to the control system, which then manages motor activation/deactivation timing to maintain engagement reliability while minimizing energy consumption during stable positioning.
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 provides improved repeatability and accuracy of measurements by maintaining engagement of the mechanical stop arrangement, even under conditions of vibration or when carrying heavy sensors, thereby enhancing metrology precision.
Implementation Method 1
a motor for moving the arm member relative to the base, and a motor controller for energising the motor to move the arm member relative to the base, wherein the motor controller is configured to energise the motor when the arm member is in the operative position to maintain engagement of the mechanical stop arrangement
Data Source
Figure 1~2
Figure 3A~3C
Figure 4~5
AI summary
A motorised measurement arm apparatus (2) for a machine tool is described. The apparatus (2) comprises a base (4; 40) for attachment to the machine tool and an arm member (6;38) extending from the base for holding one or more sensors. The arm member (6;38) is moveable relative to the base between a stowed position (26b) and an operative position (26a), the operative position being defined by engagement of a mechanical stop arrangement (50a,50b). The apparatus also has a motor (44) for moving the arm member (6;38) relative to the base (4;10) and a motor controller (52,78) for energising the motor (44) to move the arm member (6;38) relative to the base (4;40). The motor controller (52,78) is configured to energise the motor (44) when the arm member (6;38) is in the operative position to maintain engagement of the mechanical stop arrangement (50a,50b). An operative position having improved repeatability is thus obtained.