Robot Controller Force Control Using Three-Axial Sensor
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Solution Overview
Problem
Conventional three-axial force sensors are limited in controlling complex forces and moments, as they can only detect three components and struggle with four or more axis control, requiring labor-intensive production and calibration for five-axial sensors.
Innovation Solution
A robot controller system that uses a three-axial force sensor to detect forces and moments, and presumes additional forces and moments by setting a force-presuming point based on detected data, relative positional relationships, and tool/workpiece shapes, allowing for control akin to a six-axial sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a five-axial force sensor is used to detect more force components, then the force control capability is improved, but the production complexity and calibration time increase significantly
Solution Approach 1:
The patent uses a three-axial force sensor as a simplified copy of a five-axial force sensor, detecting only three force components (Fx, Fy, Fz) while presuming the other two components (Mx, My) through calculation based on geometric relationships and kinematic data, thereby avoiding the complex production and calibration required for a full five-axial sensor
Solution Approach 2:
The patent extracts only the essential three force components that can be directly measured by a simple three-axial sensor, and separates the remaining two moment components as calculated values derived from the detected forces and kinematic relationships, thus simplifying the sensing system while maintaining control capability
2Device complexity
If a three-axial force sensor is used to reduce system complexity, then the production cost and system size are reduced, but the force control capability for complex operations is limited
Solution Approach 1:
The patent replaces the mechanical sensing capability of a five-axial force sensor with a combination of a three-axial force sensor and computational algorithms that use robot kinematic data and geometric relationships to calculate the missing force components, substituting physical sensing with intelligent computation
Solution Approach 2:
The patent introduces robot arm link length data and kinematic information as intermediary elements that bridge the gap between the limited three-axial sensor measurements and the required five-axial force control, using these intermediaries to calculate the missing force components
3Ease of manufacture
If only three force components are detected to simplify the sensor structure, then the manufacturing cost is reduced, but the ability to perform four or more axis force control is insufficient
Solution Approach 1:
The patent performs preliminary action by pre-storing robot arm link length data and establishing geometric relationships before the force control operation, enabling the system to calculate missing force components in real-time without requiring complex hardware
Data Source
AI summary
A robot controller (11) which moves either a tool (4) or a workpiece (W) relative to another one with a hand unit, controls the force acting between the tool and the workpiece, comprising a force detector unit (3) for detecting a force in one axial direction and moments about the axes in two axial directions that are at right angles with the one axis and are, further, at right angles with each other; a force-presuming point setting unit (12) for setting a force-presuming point at where a force acting between the tool and the workpiece is presumed; and a force-presuming unit (13) for presuming forces in the two axial directions and a moment about the one axis based upon the force in the one axial direction and the moments about the axes in the two axial directions, and upon the position of the force-presuming point.