Machine Tool Force Estimation Using Axis Torque Compensation
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Solution Overview
Problem
Monitoring process forces on machine tools is challenging due to space constraints and the high cost of installing force-measuring sensors close to the tool center point, which reduces accuracy and adds compliant components to the kinematics.
Innovation Solution
A method that estimates process forces at the tool center point by determining and subtracting first and second sets of axis torques, eliminating the need for a force-measuring cell or sensor at the tool center point, using a physical model to simulate forces and calculate compensation angles for improved path accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force-measuring sensors are installed close to the tool center point, then measurement accuracy is improved, but space constraints and cost increase
Solution Approach 1:
The patent replaces the mechanical force measurement system (sensors, force measuring cells) with a computational approach using torque measurements and physical models. The control device calculates process forces by processing torque data from existing drive systems and applying mechanical models, eliminating the need for additional force measurement hardware at the tool center point.
Solution Approach 2:
The patent introduces torque measurements as an intermediary quantity that can be obtained from existing drive systems. Instead of directly measuring forces at the tool center point, the system measures torques at the drive axes, processes them through computational models, and derives the process forces indirectly, thus avoiding the need for direct force sensors.
2Ease of operation
If force-measuring cells are installed remotely due to space constraints, then installation is easier, but measurement accuracy decreases and compliant components are added to kinematics
Solution Approach 1:
The patent replaces the mechanical force measurement system with a computational approach using torque measurements and physical models. The control device calculates process forces by processing torque data from existing drive systems and applying mechanical models, eliminating the need for additional force measurement hardware at the tool center point.
3Measurement precision
If expensive force-measuring hardware is used, then measurement accuracy is improved, but maintenance and calibration efforts increase
Solution Approach 1:
The patent enables the system to determine process forces using its own existing sensors (torque measurements from drive systems) and built-in computational capabilities. The control device processes the torque measurements and applies physical models to calculate process forces, making the system self-sufficient without requiring external force measurement hardware that would need separate calibration and maintenance.
Solution Approach 2:
The patent replaces the mechanical force measurement system with a computational approach using torque measurements and physical models. The control device calculates process forces by processing torque data from existing drive systems and applying mechanical models, eliminating the need for additional force measurement hardware at the tool center point.
Data Source
AI summary
A method for estimating one or more process forces associated with a tool center point of a machine tool includes determining a first set of axis torques along the one or more axes of the machine tool based on a model associated with the machine tool or a first machining run without performing a machining operation, measuring a second set of axis torques along the one or more axes of the machine tool during machining, and determining the one or more process forces associated with the tool center point of the machine tool based on the first set and second set of axis torques. Accordingly, the current disclosure describes a method for estimating the process forces acting on the tool center point of the machine tool without using a forcing measuring cell or sensor at the tool center point.