Spring-Activated Brake for Humanoid Robot Motor Joints
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Solution Overview
Problem
Humanoid robots face instability and risk of falling during power outages due to interrupted motor operation, especially in large and heavy models, necessitating improved safety measures to prevent unintended movement.
Innovation Solution
A secured motorized articulation with a spring-activated brake system that includes a rotary electric motor, a brake mechanism using an elastomer shoe for frictional locking, and a linear actuator to override the spring effect, allowing controlled movement between robot limbs, along with manual override and displacement detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-activated brake system is added to the motorized articulation, then safety and stability during power outages are improved, but device complexity increases
Solution Approach 1:
The brake system is designed to automatically activate in the event of a power outage or motor failure, applying a preliminary counteracting force to prevent unintended movement. The spring-loaded brake mechanism is pre-configured to engage when power is lost, counteracting gravitational forces on the robot's limbs before safety issues can arise.
Solution Approach 2:
A force sensor acts as an intermediary element between the motor and the brake system. The sensor detects forces exceeding a predetermined threshold and triggers the brake activation, mediating between the motor's operational state and the brake's engagement to ensure safety while maintaining operational flexibility.
2Measurement precision
If a force sensor with threshold detection is implemented, then control precision and safety are improved, but device complexity and cost increase
Solution Approach 1:
The system monitors force parameters in real-time and triggers brake activation when the force parameter exceeds a predetermined threshold. This parameter-based control enables precise detection of abnormal forces while maintaining a relatively simple system architecture through the use of a single force sensor and threshold comparison logic.
3Adaptability or versatility
If the brake is designed to engage at a predetermined force threshold, then operational flexibility is improved, but the risk of unintended engagement increases
Solution Approach 1:
The force sensor serves as an intermediary that objectively measures actual forces on the limb and compares them against the predetermined threshold. This mediation ensures that brake engagement is triggered only when genuine excessive forces are detected, preventing unintended activation while maintaining operational flexibility through programmable threshold values.
Solution Approach 2:
The system incorporates feedback through the force sensor that continuously monitors limb forces and provides real-time information to the control system. This feedback loop allows the brake to be activated only when necessary, based on actual force conditions, thereby preventing unintended engagement while maintaining adaptability through adjustable threshold parameters.
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
The solution effectively prevents unintended movement during power outages, ensuring stability and safety by blocking or slowing the articulation's rotation within a predetermined threshold force, thus preventing falls and protecting robotic components.
Implementation Method 1
a brake capable of exerting a force on the mobile part of the motor by spring effect, to prevent the movement of the mobile part relative to the fixed part
Implementation Method 2
the shoe in contact with the bell housing exerts a force on the bell housing to prevent, by friction, the rotation of the shaft relative to the base pad
Data Source
AI summary
A secured motorized articulation mounted between a first and a second limb of a humanoid-type robot, comprises: a motor comprising a fixed part linked to the first limb, and a mobile part that can be moved relative to the fixed part and linked to the second limb relative to the first limb, a brake capable of exerting a force on the mobile part of the motor by spring effect, to prevent the movement of the mobile part relative to the fixed part, an actuator capable of displacing the brake by opposing the spring effect, so as to release the mobile part of the motor from the force of the brake and allow the motor to move the mobile part relative to the fixed part.