Human-Robot Interactive System with Force Sensor and Limiter
Solution Overview
Problem
In human-robot interactive systems, existing technologies face challenges in safely detecting and preventing collisions between humans and robots, especially when robots operate at high speeds or with significant power, due to difficulties in precisely estimating frictional torque and detecting direct contact forces without intermediate objects.
Innovation Solution
A human-robot interactive system is designed with a force sensor at the robot's end effector and a limiter, such as a safety fence or area sensor, to prevent direct contact between humans and the robot's first portion by allowing contact only with the second portion, which is closer to the human, and controlling the robot to avoid excessive force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If collision detection sensitivity is increased to ensure human safety, then human safety is improved, but false detection increases due to frictional torque fluctuations
Solution Approach 1:
The robot is divided into multiple portions (first robot portion and second robot portion) with different safety zones. The limiter segments the work area into a first work area where contact is prevented and a second work area where contact is allowed. This segmentation allows collision detection to be applied selectively rather than uniformly throughout the entire workspace, reducing false detections while maintaining safety.
Solution Approach 2:
A limiter (such as a safety fence or area sensor) is introduced as an intermediary device between the human and the robot's first portion. This intermediary physically or sensorially prevents the human from entering the dangerous first work area, eliminating the need for high-sensitivity collision detection in that zone and thereby reducing false detections while ensuring safety.
2Difficulty of detecting and measuring
If force sensors are attached to detect direct contact between human and robot, then contact detection capability is improved, but device complexity increases
Solution Approach 1:
The force sensor is integrated into the robot's existing structure (such as the wrist or end effector) to serve multiple functions: it detects both collision forces during normal operation and direct contact forces when a human touches the robot. This multi-functionality eliminates the need for separate contact detection sensors, reducing device complexity while improving contact detection capability.
Solution Approach 2:
The robot's existing structural components (wrist, end effector, or arm) are designed to inherently detect contact forces through their mechanical properties, eliminating the need for additional dedicated contact sensors. The structure itself serves the detection function, reducing overall system complexity.
3Productivity
If the robot operates at high speed or with large power to improve productivity, then productivity is improved, but the risk of excessive force to human increases
Solution Approach 1:
The robot's operational space is segmented into a first work area (high-risk zone) and a second work area (low-risk zone). The limiter prevents humans from entering the first work area where high-speed or high-power operations occur, while allowing interaction in the second work area. This segmentation enables the robot to maintain high productivity in the restricted zone while ensuring human safety in the accessible zone.
Solution Approach 2:
A limiter acts as an intermediary barrier between the human and the high-power robot operations. This intermediary (safety fence or area sensor) physically or sensorially separates the human from the dangerous first work area, allowing the robot to operate at high speed and power without exposing the human to excessive force risks.
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 solution ensures safe interactive work by preventing excessive force from the robot's first portion and allowing safe contact with the second portion, thereby ensuring human safety during interactions.
Implementation Method 1
the force sensor which is provided between the robot and the carried object detects the direction of the force which the human performing the interactive work applies
Implementation Method 2
a collision detection function which detects collision of a robot with its surroundings based on abnormal torque generated at the manipulator part of the robot
Data Source
AI summary
A human-robot interactive system in which a robot and a human share an area for performing interactive work, the human-robot interactive system including a force sensor which is set at an end effector attached to a front end of the robot or which is set at the robot and, when a detected value of the force sensor exceeds a predetermined value, is configured to stop the robot or controlling operation of the robot so that a detected value of the force sensor becomes smaller, the system further including a limiter which limits a work area of said human so as to prevent contact by the human with the first robot portion of the robot that is positioned further from the human than a set position of the force sensor during operation even when the robot approaches the human.