Torque Determination in Industrial Robot Gearboxes
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Solution Overview
Problem
Current methods for determining torque on a robot arm are limited in accuracy and often rely on direct torque sensors, which can be cumbersome and less robust, especially when considering the elastic properties and hysteresis of the transmission system.
Innovation Solution
A method that calculates torque on a robot arm by determining the input-side and output-side rotation angles of the transmission and using a mathematical model that accounts for the transmission's elastic properties, including hysteresis, to indirectly determine the torque, eliminating the need for direct torque sensors and enhancing the robot's stiffness and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct torque sensors are used to determine torque on the robot arm, then torque measurement is obtained, but the system becomes more complex and less robust
Solution Approach 1:
The patent replaces direct mechanical torque sensors with an indirect calculation method using a mathematical model. The torque is determined by processing signals from angle measuring devices (encoders) that measure rotation angles at different positions in the transmission chain, eliminating the need for physical torque sensors and reducing system complexity while maintaining measurement capability
Solution Approach 2:
The patent introduces a mathematical model of the transmission system as an intermediary between the measurable quantities (rotation angles) and the desired quantity (torque). This model acts as a mediator that translates angle measurements into torque values, avoiding direct mechanical sensing while preserving the information needed for torque determination
2Reliability
If torque sensors are installed in the transmission system, then torque can be measured, but the robot's stiffness and robustness are reduced
Solution Approach 1:
The patent replaces physical torque sensors with a computational approach using a mathematical model of the transmission system. This substitution eliminates mechanical sensing elements that would reduce structural stiffness, while the model processes data from existing angle sensors to provide reliable torque determination without compromising the robot's mechanical integrity
3Measurement precision
If a mathematical model accounting for elastic properties is used, then torque determination accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent incorporates elastic properties and hysteresis effects as additional parameters in the mathematical model of the transmission system. By including these parameters (elastic moduli, damping coefficients, hysteresis characteristics), the model achieves higher accuracy in torque determination while remaining computationally tractable through standard numerical methods
Solution Approach 2:
The patent uses feedback from multiple angle measuring devices positioned at different locations in the transmission chain. The mathematical model processes these feedback signals, comparing measured angles with model predictions to accurately determine torque while compensating for elastic deformations and hysteresis effects through the established relationships in the model
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 approach allows for more precise and robust torque determination, increasing the accuracy of the robot's movement control and enabling real-time monitoring for defects in the transmission, such as broken teeth, while reducing the need for torque sensors, making the robot stiffer and more robust.
Implementation Method 1
a mathematical model of the gearbox, which takes into account, in particular, the elastic properties of the gearbox
Implementation Method 2
the mathematical model takes into account the elastic properties of the gearbox, including hysteresis
Data Source
Figure 1
Figure 2~3
AI summary
The method involves determining an angle of rotation turned toward a driving side of a stationary motor (11) of a robotic arm (2) of an industrial robot (1) and an angle of rotation turned toward reducing side of a gearbox (12) connected to the stationary motor. A torque having an effect on one of sequentially arranged limbs (3-7) based on the determined driving side and reducing side angles of rotation based on a mathematical model of the gearbox is determined with respect to particular elastic properties of the gearbox. An independent claim is also included for an industrial robot.