Robot Arm Joint Electrical Braking for Gravity Hold on Fault
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Solution Overview
Problem
Existing robot arms face challenges in efficiently detecting and responding to faults, particularly in maintaining position without increasing weight or space requirements through mechanical brakes.
Innovation Solution
A robot arm design that incorporates a multiple-phase motor with a controller configured to apply a braking current to maintain the joint position against gravity upon fault detection, utilizing electrical braking instead of mechanical brakes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical brake is incorporated into the drive train of each motor to hold the robot arm in position during fault assessment, then the robot arm can maintain its position against gravity, but the weight of the robot arm increases and space within the robot arm is consumed
Solution Approach 1:
The patent replaces the mechanical brake system with an electrical braking system. The controller applies a braking current to the motor windings, creating electromagnetic torque that holds the joint in position against gravity. This substitution eliminates the need for mechanical brake components, thereby reducing the weight of the robot arm while maintaining the position holding capability during fault assessment.
Solution Approach 2:
The patent changes the operational parameter of the motor from standard driving current to braking current. By controlling the magnitude and direction of the current applied to the motor windings, the system generates the appropriate electromagnetic torque to hold the joint position. This parameter-based control achieves position holding without requiring additional mechanical braking components.
2Reliability
If a mechanical brake is incorporated into the drive train of each motor to hold the robot arm in position during fault assessment, then the robot arm can maintain its position against gravity, but the space within the robot arm is consumed
Solution Approach 1:
The patent replaces the mechanical brake system with an electrical braking system. The controller applies a braking current to the motor windings, creating electromagnetic torque that holds the joint in position against gravity. This substitution eliminates the need for mechanical brake components, thereby reducing the space occupied within the robot arm while maintaining the position holding capability during fault assessment.
3Weight of moving object
If electrical braking is applied by controlling current to motor windings, then the weight and space requirements are reduced, but the system requires precise control of braking current to maintain position against gravity
Solution Approach 1:
The patent makes the motor serve multiple functions: it acts as both a driving motor during normal operation and as an electrical brake during fault conditions. By controlling the current applied to the motor windings, the same motor component performs both propulsion and position holding functions, eliminating the need for separate braking mechanisms and reducing overall system complexity despite the electrical control requirements.
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 allows for effective fault detection and response, maintaining the robot arm's position without the weight and space penalties of mechanical brakes, while ensuring efficient operation and safety.
Implementation Method 1
the controller configured to electrically brake the motor in response to detection of a fault in the robot arm by applying a braking current to the motor so as to maintain the position of the joint against gravity
Data Source
AI summary
A robot arm comprising: a first link connected to a second link by a joint, the joint permitting the second link to move relative to the first link; a motor for driving the joint; and a controller for controlling the motor. The controller is configured to electrically brake the motor in response to detection of a fault in the robot arm by applying a braking current to the motor so as to maintain the position of the joint against gravity. The controller only performs this electrical braking if the joint is in a configuration in which the robot arm will droop under gravity if the joint is not actively driven.