Active Contact Force Control With Spherical Joints and Damping
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Solution Overview
Problem
Existing apparatuses for active force control in machining and handling operations face challenges in precise measurement of axial force, attenuation of rapid oscillations, and compensation for gravity influences, particularly when dealing with uneven workpiece surfaces and multi-axis machines.
Innovation Solution
The apparatus incorporates a linear actuator with a ball screw, a force sensor connected via spherical joints and mechanical dissipative elements (MDE) to measure and attenuate axial forces, while an inertial measurement unit compensates for gravity, ensuring precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is directly connected to the linear actuator, then the measurement of axial force is simplified, but non-axial loads and rapid oscillations affect measurement precision
Solution Approach 1:
The patent introduces spherical joints and mechanical dissipative elements as intermediary components between the linear actuator and force sensor. These intermediaries serve multiple functions: spherical joints eliminate non-axial load transmission while mechanical dissipative elements attenuate rapid oscillations, thereby protecting the force sensor from disturbing influences and improving measurement precision without requiring direct rigid connection
Solution Approach 2:
The mechanical connection is segmented into multiple functional sections: the actuator connection section, spherical joint section, mechanical dissipative element section, and force sensor section. This segmentation allows each component to perform its specific function independently, with spherical joints handling orientation alignment and oscillation attenuation, while the force sensor专注于force measurement
2Measurement precision
If spherical joints and mechanical dissipative elements are added to eliminate non-axial loads and attenuate oscillations, then measurement precision improves, but device complexity increases
Solution Approach 1:
The spherical joints and mechanical dissipative elements serve multiple functions simultaneously: they eliminate non-axial loads, attenuate rapid oscillations, accommodate misalignment, and protect the force sensor. This multi-functionality reduces the need for additional specialized components, making the added complexity worthwhile by achieving superior measurement precision through a compact integrated design
3Weight of moving object
If the linear actuator is positioned closer to the multi-axis machine, then tool inertia is reduced, but control of contact force becomes more difficult
Solution Approach 1:
The apparatus acts as an intermediary system between the multi-axis machine and the production tool. It incorporates a linear actuator with spherical joints and mechanical dissipative elements that actively control contact force, thereby decoupling the inertia benefits of close positioning from the control difficulties, allowing the tool to be positioned optimally while maintaining precise force control through the intermediary apparatus
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 enables accurate and robust active force control, reducing non-axial load effects and oscillations, allowing for faster and more precise machining operations.
Implementation Method 1
a mechanical dissipative element between the force sensor and the upper flange, to mechanically attenuate changes in contact force measured by the force sensor
Implementation Method 2
The second mechanical connection of the ball screw and the upper flange includes a force sensor to measure force by which the linear actuator is acting on the upper flange and thereby on the production tool. The second mechanical connection between the ball screw and the upper flange is formed based on a first spherical joint and a mechanical dissipative element between the force sensor and the upper flange, and based on a second spherical joint between the force sensor and the ball screw, where the first and second spherical joints are to eliminate any non-axial load
Data Source
AI summary
An apparatus for active contact force control can have an upper flange on which to mount a production tool. The apparatus can be mounted, via a lower flange, on a multi-axis machine to obtain spatial motion together with the corresponding production tool. The apparatus can comprise a housing inside which can be a linear actuator connected to guides. Mechanical connection between a ball screw and the upper flange can contain a force sensor and at least one spherical joint. The connection between the spherical joint and the upper flange can be formed using a mechanical dissipative element made of elastic dissipative elements and a disc plate positioned between the elastic dissipative elements.