Robotic Arm Joint Friction Detection Using Brake Test Torque
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Solution Overview
Problem
Existing robotic arm systems lack an efficient and cost-effective method to detect and evaluate friction status in joints, often requiring additional sensors and manual interpretation of secondary symptoms, which can lead to undetected overloading and increased wear.
Innovation Solution
A method that automatically detects friction status in robotic arm joints by executing a brake test procedure using existing motor control systems, evaluating motor torques in both rotational directions to calculate the moment of friction without separate sensors, and comparing it against prespecified thresholds or historical data to determine if the friction is within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate sensors are added to detect friction in joints, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The motor control system is made multi-functional by enabling it to perform both its primary function (controlling motor operation) and a secondary function (detecting friction status through torque analysis). The existing motor controller executes brake test procedures and analyzes motor torque data to determine joint friction status, eliminating the need for separate friction sensors. This is achieved by evaluating motor torque during brake test procedures and comparing it against threshold values to detect excessive friction in joints.
Solution Approach 2:
The motor control system serves itself by using its own operational data (motor torque during brake tests) to monitor the health status of the robotic arm joints. The system performs self-diagnosis by analyzing the relationship between motor torque and joint friction, allowing it to detect problems without external monitoring equipment. This self-service capability reduces system complexity while maintaining detection accuracy.
2Device complexity
If manual interpretation of secondary symptoms is used, then device complexity is reduced, but reliability of detection deteriorates
Solution Approach 1:
A feedback mechanism is implemented where the motor control system continuously monitors motor torque during brake test procedures and automatically compares the measured torque against predefined threshold values. When the torque exceeds the threshold, the system generates an automated alarm signal indicating excessive joint friction. This closed-loop feedback system replaces manual interpretation with automated decision-making, improving detection reliability while maintaining simple system architecture.
3Measurement precision
If additional sensors and monitoring equipment are installed, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The motor control system is designed to perform multiple functions using the same hardware infrastructure. The existing motor controllers, which are already installed for driving the robotic arm, are enhanced to execute brake test procedures and analyze torque data for friction detection. This multi-functional approach eliminates the need for additional sensors and monitoring equipment, thereby avoiding increased manufacturing costs while maintaining high detection precision.
4Productivity
If brake test procedures are automatically executed with torque evaluation, then productivity is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary diagnostic actions by automatically executing brake test procedures at scheduled intervals or upon request. During these tests, the motor control system preemptively evaluates motor torque to detect potential joint friction issues before they lead to failures. This preliminary monitoring enables proactive maintenance planning, improving productivity by reducing unplanned downtime while using existing control capabilities.
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 method allows for the early detection of defective brakes and excessive friction, preventing overloading and wear, and enabling quicker identification of issues by service technicians, all without the need for additional sensors, thereby improving maintenance efficiency and reducing energy consumption.
Implementation Method 1
a robot controller (10) which is designed to control a plurality of electric motors (M1-M6) of the robotic arm (9), said electric motors being associated with the joints (L1-L6) of the robotic arm, in order to move the robotic arm (9)
Implementation Method 2
associated brakes of the robotic arm, in order to move the robotic arm
Data Source
AI summary
A method, a robot, and a computer program product for detecting and evaluating a friction status in at least one joint of a robotic arm, wherein, within the scope of a brake test program, at least one motor of a plurality of electric motors is driven automatically in a first rotational direction, wherein a detection of a first motor torque in the driven motor takes place during its rotation in the first rotational direction. The at least one motor is then driven in a second rotational direction opposite the first rotational direction, wherein a detection of a second motor torque in the driven motor takes place during its rotation in the second rotational direction. An automatic evaluation of the first motor torque and the second motor torque takes place in order to obtain the friction torque of the joint associated with the driven motor.