Robot Load Gravity Center Estimation from Single-Posture Torque Sensing
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Solution Overview
Problem
Conventional methods for estimating the weight and position of a load on a robot require multiple postures and measurements, which prolongs the conveying time, especially in material flow systems where workpieces with varying weights and gravity centers need frequent estimation.
Innovation Solution
A device and method using sensors to detect torques and forces applied to different portions of a robot, allowing for the calculation of a load's weight and horizontal position in a single posture, eliminating the need for multiple robotic postures during measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple postures are used for measurement, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent transitions from measuring torque at multiple robot postures (spatial dimension) to measuring torque at multiple axes simultaneously at a single posture (dimensional shift). By utilizing torque sensors at different rotational axes of the robot arm, the system obtains sufficient measurement data from a single posture configuration, thereby eliminating the time-consuming posture changes while maintaining measurement accuracy through multi-axis torque data fusion.
2Measurement precision
If multiple postures are used for measurement, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The invention shifts the measurement approach from temporal sequencing (multiple postures over time) to spatial parallelism (multiple axes simultaneously at one posture). This dimensional transformation allows the system to gather equivalent measurement information faster, directly improving conveying efficiency in material flow systems where rapid weight and position estimation is critical.
3Loss of time
If torque sensors are installed at multiple axes, then device complexity increases, but loss of time decreases
Solution Approach 1:
The patent applies partial action by installing torque sensors at only two specific axes of the robot arm rather than all axes. This selective sensor placement provides sufficient measurement data for accurate weight and position estimation while avoiding the excessive complexity of full-axis instrumentation. The method uses minimal necessary sensors to achieve the measurement objective efficiently.
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
Enables accurate and efficient estimation of a load's weight and horizontal position without changing the robot's posture, reducing conveying time and improving control accuracy in robotic operations.
Implementation Method 1
at least one sensor configured to detect a first torque applied to a first portion of a robot, and a second torque applied to a second portion of the robot different from the first portion or a force applied to the robot
Data Source
AI summary
A device, a method and a program, by which a weight and a horizontal position of a gravity center of a load attached to a movable part of a robot can be estimated by a simple configuration. The device has: two torque sensors configured to detect a first torque applied to a first axis of a robot, and a second torque applied to a second axis of the robot; and a calculation section configured to calculate a weight and a horizontal position of a gravity center of a workpiece, by using two detection values of the torque sensors in one posture in which a hand attached to a movable part of the robot holds the workpiece.