Traction Drive System for Articulated Robotic Arms
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing robotic arms for vending machines lack independent movement of arm members from their motors, leading to potential damage and safety concerns, and rely on non-absolute position encoders which are prone to accuracy issues due to electrical noise.
Innovation Solution
A traction drive system with an input drive disk, spider, traction balls, traction plate, and clamping device, along with an absolute rotational position sensor system, allowing for decoupled rotation and precise position feedback, reducing the risk of damage and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If robotic arm members are permanently coupled to their driving motors, then the motor can continuously drive the arm member, but damage to drivetrain components or motor is possible when the arm member halts due to collision or jam
Solution Approach 1:
The patent introduces a friction drive system with friction wheels that contact the arm member as an intermediary between the motor and the arm member. This friction-based coupling allows the motor to drive the arm member during normal operation while automatically disengaging when the arm member halts or reverses, preventing damage without requiring complex mechanical couplings or clutches
Solution Approach 2:
The patent replaces traditional mechanical coupling mechanisms (gears, belts, direct drive) with a friction-based contact system. The friction wheels contact the arm member's outer surface, using friction forces rather than mechanical interlocking, which enables smooth engagement and disengagement to protect against damage
2Ease of operation
If the motor continuously drives the robotic arm member, then automation is maintained, but personal safety is compromised as the motor will continue to drive the arm member even during manual operation
Solution Approach 1:
The friction drive system acts as a safety intermediary by automatically disengaging when the arm member is manually moved. The friction contact allows the arm member to be freely manipulated during manual operation without the motor applying driving forces, eliminating the safety hazard while maintaining automation during normal operation
Solution Approach 2:
The patent implements a dynamic drive system where the coupling between motor and arm member is not fixed but adapts based on operational mode. During automated operation, the friction wheels maintain contact for power transmission; during manual operation, the arm member can be freely moved without motor interference, providing inherent safety
3Measurement precision
If non-absolute position encoders are used to provide position feedback, then device complexity is reduced, but position accuracy is reduced due to electrical noise causing lost encoder pulses
Solution Approach 1:
The patent replaces electrical position sensing (encoders) with a magnetic field-based absolute position sensor. This magnetic sensor system provides absolute position feedback that is inherently immune to electrical noise and pulse loss, achieving high position accuracy without the complexity of incremental encoder systems requiring continuous pulse counting
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the arm member's position and the sensor system. The magnetic field carries position information that can be detected by the absolute position sensor, providing a noise-resistant communication channel that eliminates the vulnerability of electrical encoder pulses to electromagnetic interference
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 traction drive system prevents damage to drivetrain components and motors by enabling controlled slippage, while the absolute position sensor system provides high precision and safety, allowing for safe manual operation and accurate robotic arm programming.
Implementation Method 1
the array of traction balls can roll in a circular path on both the surface of the input drive disk and the surface of the traction plate
Implementation Method 2
If the frictional forces between the traction balls, the input drive disk, and traction plate are greater than the tangential forces acting on the traction balls due to torque applied to the input drive disk, the traction balls will continue to roll in the circular path and maintain a coupled rotation between the input drive disk and the output drive shaft
Data Source
AI summary
A traction drive system for an articulated robotic arm. The traction drive system can include an input drive disk, a spider, an array of traction balls, a traction plate, an output drive shaft, a clamping device to load the traction balls, and an absolute rotation position sensor system. The rotation of the output drive shaft can be coupled to the rotation of the input drive disk while the traction balls are frictionally engaged to the drive disk surface and traction plate surface. The rotational connection can be decoupled when the traction balls are not frictionally engaged to the drive disk surface and traction plate surface. A rotational position sensor located in proximity to the traction drive can provide absolute rotational position feedback of the output drive shaft.