Robot Surface Following Using Virtual Shape Normal Control
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Solution Overview
Problem
Existing robot control methods for following curved surfaces require advance shape measurement by contact, which is complex and can damage soft objects like balloons.
Innovation Solution
A curved surface following control method for robots that includes a normal direction identification process and a work tool posture control process, allowing the robot to follow a curved surface without prior shape measurement by using a virtual shape approximation and maintaining contact force with a force sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based shape measurement is performed to acquire target workpiece geometry, then shape information accuracy is improved, but the complexity of advance preparation increases and soft objects may be damaged
Solution Approach 1:
The patent creates a virtual shape model (copy) of the target workpiece based on approximate geometric formulas rather than performing actual contact-based physical measurement. This virtual copy contains sufficient information for robot control without requiring complex physical scanning procedures, thereby reducing preparation complexity while maintaining adequate measurement precision for the control task.
Solution Approach 2:
The patent replaces the mechanical contact-based measurement system with a computational approach using approximate geometric formulas and virtual shape modeling. This substitution eliminates the need for physical contact during measurement, simplifying the preparation process and preventing damage to soft objects while still providing accurate enough shape information for robot following control.
2Measurement precision
If contact-based shape measurement is performed to acquire target workpiece geometry, then shape information accuracy is improved, but the risk of damaging soft objects increases
Solution Approach 1:
The patent creates a virtual shape model (copy) of the target workpiece based on approximate geometric formulas rather than performing actual contact-based physical measurement. This virtual copy contains sufficient information for robot control without requiring complex physical scanning procedures, thereby reducing preparation complexity while maintaining adequate measurement precision for the control task.
Solution Approach 2:
The patent replaces the mechanical contact-based measurement system with a computational approach using approximate geometric formulas and virtual shape modeling. This substitution eliminates the need for physical contact during measurement, simplifying the preparation process and preventing damage to soft objects while still providing accurate enough shape information for robot following control.
3Device complexity
If virtual shape approximation is used instead of contact measurement, then advance preparation is simplified and soft objects are protected, but measurement precision may be reduced
Solution Approach 1:
The patent applies partial measurement by using approximate geometric formulas that capture the essential shape characteristics without performing complete precise measurement. This partial action approach provides sufficient shape information for robot following control without the complexity and potential harm of complete contact-based measurement, accepting that full measurement precision is not necessary for the control task.
Solution Approach 2:
The patent changes the measurement parameters from exact physical dimensions to approximate geometric parameters that are sufficient for control purposes. By using formulas that represent the general shape (e.g., cylindrical, spherical approximations) rather than exact surface geometry, the system achieves adequate precision for following control while simplifying preparation and protecting soft objects.
4Manufacturing precision
If force-controlled contact is used to follow curved surface, then following precision is improved, but the preparation process becomes more complex
Solution Approach 1:
The patent performs preliminary action by creating a virtual shape model and calculating the normal directions in advance before the robot begins following control. This pre-computation of geometric information simplifies the real-time control process, as the robot only needs to follow the pre-calculated trajectory and maintain force-controlled contact, rather than performing complex real-time shape analysis.
Solution Approach 2:
The patent introduces a virtual shape model as an intermediary between the robot control system and the actual target workpiece. This intermediary contains pre-calculated geometric information and normal directions that mediate the control process, allowing the robot to achieve precise following control without directly interacting with the complex real-world geometry during operation.
Data Source
AI summary
A surface following control method for a robot is used for controlling the robot including a hand part, an arm part, and a controller. In this surface following control method for the robot, processes including a normal direction identification process and a work tool posture control process are performed. In the normal direction identification process, a normal direction of a virtual shape at a virtual position where the work tool attached to the hand part contacts the virtual shape which is a shape represented by the formula is identified. In the work tool control process, the work tool attached to the hand part is brought into contact with the target workpiece at a corresponding position which is a position corresponding to the virtual position on the surface of the target workpiece, in a posture along the normal direction identified in the normal direction identification process.