Robot Joint Torque Feedback for Jerk-Limited Motion Control
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Solution Overview
Problem
Existing robot control methods fail to optimize acceleration-and-deceleration control effectively, leading to excessive load torque on transmission components, which can damage the robot and increase cycle time, due to simplified vibration models that do not account for real-world conditions and individual robot variations.
Innovation Solution
A method and device that measure load torque and adjust the rate of change in acceleration of each joint based on comparison with allowable ranges, using torque sensors and a control unit to optimize acceleration-and-deceleration patterns in real-time, ensuring the load torque remains within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the robot joints are sharply accelerated and decelerated to increase production speed, then the production speed increases, but the transmission components receive excessive load which is not preferable for durability
Solution Approach 1:
The patent applies dynamics by making the acceleration-and-deceleration pattern adjustable and adaptable. The control device dynamically adjusts the jerk limiting value based on actual torque measurements from torque sensors, allowing the system to optimize between speed and durability depending on real-time conditions rather than using fixed parameters.
Solution Approach 2:
The patent changes parameters by adjusting the jerk limiting value (rate of change of acceleration) based on actual torque measurements. The control device modifies acceleration patterns dynamically by changing the jerk parameter according to measured torque values, enabling optimized control that prevents excessive load while maintaining high speed operation.
2Device complexity
If a simplified vibration model is used for control, then the control calculation is simple, but the model does not accurately reflect real-world conditions and individual robot variations requiring parameter adjustment for each environment
Solution Approach 1:
The patent implements feedback by using torque sensors to measure actual load torque on transmission components and using this measurement to adjust the jerk limiting value. This closed-loop feedback mechanism allows the system to adapt to real-world conditions and individual robot variations without requiring complex pre-calibration for each environment.
Solution Approach 2:
The control device performs self-adjustment by automatically modifying the jerk limiting value based on torque sensor measurements. The system serves itself by autonomously optimizing its acceleration patterns according to actual operating conditions without requiring external intervention or manual parameter tuning for different environments.
3Reliability
If a large margin is set in the jerk limiting value to ensure safety, then the transmission components are protected, but the operation time becomes longer
Solution Approach 1:
The patent resolves this contradiction by making the jerk limiting value dynamic rather than static. The control device continuously adjusts the jerk limit based on real-time torque measurements, allowing the system to operate at maximum safe speed when conditions permit and reduce speed only when necessary to protect components, thereby minimizing operation time while ensuring protection.
Solution Approach 2:
The patent changes the jerk limiting parameter dynamically based on measured torque conditions. By adjusting this parameter in real-time according to actual load conditions, the system achieves optimal balance between speed and protection, avoiding the time loss associated with consistently conservative fixed margins.
4Productivity
If the jerk limiting value is increased to shorten cycle time, then the operation speed increases, but the load torque may exceed the maximum allowable torque causing damage to the robot
Solution Approach 1:
The patent uses feedback from torque sensors to monitor actual load torque in real-time and adjusts the jerk limiting value accordingly. This feedback mechanism prevents excessive load torque by dynamically reducing the jerk limit when torque approaches maximum allowable values, while allowing higher speeds when torque margins are sufficient.
Solution Approach 2:
The patent replaces conservative mechanical design margins with intelligent control based on actual torque measurements. Instead of designing for worst-case scenarios with large safety margins, the system uses sensor feedback and adaptive control to dynamically manage load torque, achieving higher speeds without exceeding mechanical limits.
Data Source
AI summary
A method of controlling a robot having a plurality of joints includes measuring load torque applied to a driving-force transmission system of each of the plurality of joints while moving a hand of the robot along a predetermined path, comparing a measurement value of the load torque and an allowable range of each of the joints, and controlling a rate of change in acceleration of the driving-force transmission system of each of the joints, depending on a comparison result, in a next operation in which the hand of the robot is moved along the predetermined path.