Self-Positioning Swivel Caster Cam Mechanism for Robotic Clearance
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Solution Overview
Problem
Existing movable material handling equipment with freely-rotating swivel casters face challenges in maintaining defined positions during operations, leading to variable clearance and potential collisions with robotic drive units due to random orientations and surface irregularities, which hinder efficient and reliable movement and retrieval.
Innovation Solution
Self-positioning swivel casters with defined home positions, utilizing a mechanism comprising a caster wheel, swivel frame, bearing, lower and upper cams, and a compression spring, that align and maintain orientation based on surface characteristics, preventing drift and ensuring consistent clearance for robotic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If freely-rotating swivel casters are used, then turning and movement in various directions is facilitated, but the casters are positioned in substantially random positions when the cart is not being moved
Solution Approach 1:
The cam mechanism is pre-configured with specific geometric profiles that automatically guide the caster to a predetermined home position when the cart is stationary. The cam lobe geometry is designed in advance to provide the necessary mechanical advantage and positioning force, eliminating the need for active control during operation.
Solution Approach 2:
The self-positioning mechanism uses the cart's own weight and the cam-follower interaction to automatically return the caster to its home position without requiring external power or control systems. The spring-loaded follower engages with the cam profile to provide automatic positioning based on the cart's stationary state.
2Adaptability or versatility
If freely-rotating swivel casters are used, then directional flexibility is improved, but variable clearance and potential collisions with robotic drive units occur
Solution Approach 1:
The home position of the caster is predetermined through cam geometry design, ensuring that when the cart is stationary, the caster is automatically positioned at a specific orientation that maintains consistent clearance with robotic drive units. This pre-planned positioning eliminates random orientations that cause variable clearance.
3Ease of operation
If swivel casters are used to facilitate movement, then ease of operation is improved, but drift along floor slopes occurs due to surface irregularities
Solution Approach 1:
The cam mechanism is pre-designed with asymmetric profile geometry that creates a stable equilibrium position. When the cart is stationary, the cam-follower interaction automatically positions the caster at a specific angle relative to the cart frame, preventing drift along floor slopes by maintaining a predetermined stable orientation.
4Manufacturing precision
If a self-positioning mechanism with cams and springs is added, then position definition is improved, but device complexity increases
Solution Approach 1:
The self-positioning function is extracted from complex active control systems and implemented through a simple passive cam-follower mechanism. The cam profile geometry alone provides the positioning logic, eliminating the need for sensors, motors, or control algorithms while achieving reliable home position return.
Solution Approach 2:
The mechanism uses simple, inexpensive components such as steel cams, spring followers, and bearing assemblies that can be easily manufactured and replaced if needed. The cam profiles are machined from standard materials and can be produced cost-effectively, making the overall mechanism economically viable despite added parts.
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 self-positioning swivel casters maintain consistent clearance and prevent drift, enabling reliable robotic handling by ensuring carts remain stationary and aligned, minimizing collisions and facilitating efficient movement in material handling facilities.
Implementation Method 1
a compression spring positioned between the upper cam and the cart frame, the compression spring may be configured to apply a force to the upper cam
Implementation Method 2
an upper cam rotatably coupled to the cart frame, a lower cam coupled to the swivel caster frame, the upper cam and the lower cam may have surfaces configured to cause the lower cam, the swivel caster frame, and the caster wheel to rotate to a defined home position
Implementation Method 3
the compression spring may be configured to apply a force to the upper cam that overcomes friction between the upper cam and the lower cam
Data Source
AI summary
A self-positioning swivel caster may include a swivel mechanism that defines a home position of the caster. The swivel mechanism may include a compression spring, an upper cam, and a lower cam that is coupled to the caster wheel, in which the upper and lower cams include mating surfaces that define the home position. A bias force applied by the compression spring to the upper cam may cause rotation of the lower cam to the home position. When coupled to mobile containers, self-positioning swivel casters in home positions may increase clearance under the mobile containers for robotic drive units or other material handling equipment used to move the mobile containers, and the self-positioning swivel casters in home positions may also prevent drift or rolling of the mobile containers away from current locations.