Legged Robot Center-of-Gravity Estimation Without Force Sensors
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Solution Overview
Problem
Legged robots equipped with force sensors for center of gravity estimation face high manufacturing and operation costs due to the expense and fragility of the sensors, which are prone to deformation under heavy loads.
Innovation Solution
An information processing device that calculates and estimates the center of gravity of a robot device based on torque applied to its joints and reaction force from the ground contact surface, eliminating the need for force sensors by using torque and link length data to determine the reaction force and subsequently the center of gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is used to estimate the center of gravity, then the measurement precision is improved, but the manufacturing cost increases and the reliability decreases
Solution Approach 1:
The patent replaces the mechanical force sensor system with a computational mechanics approach. By measuring torque at joints and link lengths, the system calculates reaction forces and estimates the center of gravity through mathematical computation rather than direct mechanical sensing. This substitution eliminates the force sensor while achieving the same measurement objective through a more reliable and cost-effective method.
2Measurement precision
If a force sensor is installed on the leg portion, then the center of gravity can be estimated, but the manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive force sensor hardware with a computational approach using existing torque measurements and link length data. The system calculates reaction forces at the ground contact point and estimates the center of gravity through mathematical computation, eliminating the need for costly force sensors while achieving the same measurement capability.
3Measurement precision
If a force sensor is used for center of gravity estimation, then the measurement precision is improved, but the operation cost increases due to frequent replacement
Solution Approach 1:
The patent replaces the force sensor system with a computational approach that uses torque measurements from joint motors and link length parameters. This substitution eliminates the force sensor that required frequent replacement, thereby reducing operation and maintenance costs while maintaining center of gravity estimation accuracy throughout the robot's operational life.
4Measurement precision
If a force sensor is installed on the leg portion, then the center of gravity can be estimated, but the device complexity increases
Solution Approach 1:
The patent replaces the physical force sensor installation on the leg portion with a computational system that processes torque data from joint motors and link length information. This substitution simplifies the device by eliminating additional sensors and their associated wiring and calibration requirements, while achieving center of gravity estimation through mathematical computation of reaction forces.
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 approach reduces the production and operational costs of legged robots by estimating the center of gravity without expensive force sensors, improving stability and reducing the frequency of sensor replacement.
Implementation Method 1
calculates, on the basis of torque applied to one or more joints included in each of a plurality of leg portions, reaction force applied from a ground contact surface to each of the plurality of leg portions
Data Source
AI summary
A center of gravity of a robot device is estimated without utilization of a force sensor or the like. An information processing device including a center-of-gravity estimation unit that calculates, on the basis of torque applied to one or more joints included in each of a plurality of leg portions, reaction force applied from a ground contact surface to each of the plurality of leg portions, and that estimates a center of gravity of a robot device including the plurality of leg portions on the basis of the calculated reaction force on the plurality of leg portions.