Robotic Payload Characterization via Motor Current Analysis
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Solution Overview
Problem
Automated robotic systems, such as those used in video production, operate without knowledge of the payload weight, mass, or size, and the surrounding environment, leading to potential system wear and poor image quality due to uninformed movements.
Innovation Solution
The method involves determining key operating characteristics of a robotic system, including payload center of mass, holding force, static friction, and traction, by controlling motors to measure forces and torques at various positions, and using this data to characterize the mechanical environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robot operates without knowledge of payload weight, mass, or size, then the system is simpler to operate, but mechanical wear increases and image quality deteriorates
Solution Approach 1:
The system performs preliminary characterization of the payload by automatically determining its mass, center of mass position, and moment of inertia before operation begins. This preliminary action enables the control system to adjust operational parameters in advance, preventing mechanical wear and ensuring reliable operation without requiring complex manual setup procedures
2Loss of time
If the robot operates without knowledge of payload weight, mass, or size, then the setup process is faster, but image quality deteriorates
Solution Approach 1:
The system performs self-characterization by automatically measuring its own payload properties using onboard sensors and actuators. The robot determines mass, center of mass, and moment of inertia through automated procedures without requiring external measurement equipment or manual input, thereby maintaining fast setup while ensuring accurate operational parameters for image quality
3Reliability
If the system characterizes the robotic system by determining payload parameters through multiple measurements, then the operational reliability improves, but the complexity of the system increases
Solution Approach 1:
The system replaces complex manual measurement procedures with automated sensor-based characterization. Using motor current measurements, position feedback from encoders, and controlled movement sequences, the system automatically determines payload mass, center of mass, and moment of inertia, achieving high operational reliability without adding significant hardware complexity
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 setup and operation within mechanical constraints, reducing wear and improving image quality by providing essential environmental and payload data for robotic systems.
Implementation Method 1
determining a location of a center of mass of the payload by: controlling the motor to hold the payload static in at least three angular positions, and for each position determining a respective torque applied by the motor to hold the payload static
Implementation Method 2
controlling the lift motor to sequentially raise the column to a plurality of vertical positions and to hold the column steady while in each of the plurality of vertical positions; for each vertical position, determining a force applied by the lift motor to hold the column steady
Implementation Method 3
determining holding force F0 and static friction Ffs about an axis of a robotic system at a first position
Data Source
AI summary
A method of accommodating a payload and determining a working environment in a robotic system is disclosed. The method is directed to using a motor current measurement taken at the axis motors of a robotic system to calculate various parameters including payload balance, mass, moment of inertia, friction force and traction force. This measurement is based on the known relationship between motor current and motor torque.