Spring-Centered Caster Wheel Alignment for Sensor Clearance
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Solution Overview
Problem
Autonomous delivery vehicles face challenges in maintaining the orientation of swivel caster wheels within the field of view of short-range sensors, which can interfere with obstacle and surface detection, and require an apparatus to stabilize the caster wheels relative to the vehicle.
Innovation Solution
An apparatus comprising a spring actuator with a compression spring, swashshaft, and follower mechanism that applies a restoring force to maintain the caster wheels in a desired rotational position aligned with the vehicle's centerline, minimizing pivoting and interference with sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the swivel caster is lifted off the ground, then the caster can pivot freely to align with direction of travel, but the caster moves within the FOV of sensors and interferes with obstacle/surface detection
Solution Approach 1:
The spring actuator applies a preliminary restoring force to counteract the caster's tendency to pivot away from the design position. This anti-action force increases with angular deviation, preventing the caster from moving into the sensor field of view while still allowing controlled pivoting when needed for navigation
Solution Approach 2:
The spring actuator changes the mechanical parameter of restoring force based on the angular position of the caster. As the angular difference from design position increases, the spring force increases proportionally, creating a position-dependent constraint that limits caster movement within the sensor FOV
2Object-affected harmful factors
If the spring actuator applies strong restoring force to maintain caster position, then sensor interference is reduced, but the force required to pivot the caster increases
Solution Approach 1:
The spring actuator provides a dynamic restoring force that adapts to the caster's angular position. The force is minimal at the design position and increases progressively with angular deviation, allowing easy pivoting for small adjustments while strongly restraining large movements that would interfere with sensors
3Manufacturing precision
If the follower is constrained to move axially only, then the spring compression is controlled precisely, but the mechanism complexity increases
Solution Approach 1:
The swashshaft acts as an intermediary between the caster's rotational movement and the follower's axial movement. It converts the rotational angular displacement into linear compression of the spring through its inclined surface, precisely controlling spring compression without requiring complex direct constraint mechanisms
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 apparatus effectively stabilizes caster wheels, reducing interference with sensor fields of view and improving obstacle detection by maintaining caster wheels in a predetermined orientation, enhancing navigation and obstacle avoidance capabilities.
Implementation Method 1
The spring actuator includes a compression spring oriented along the castor pivot axis
Implementation Method 2
The spring actuator that applies a force on the second part that increases with an angular difference between the rotational position and the design position
Implementation Method 3
The swashshaft including a bearing surface characterized by swashshaft axis that intersects the caster pivot axis at an acute angle and the bearing surface is centered on the swashshaft axis
Data Source
AI summary
An autonomous delivery vehicle having one or more caster wheels that may be held off the ground for a portion of the time that the autonomous delivery vehicle travels. Each caster wheel is mounted in a pivot with a centering mechanism to hold the caster wheels in a design orientation. The caster wheel in the design orientation maximizes the view of forward-looking sensors on the autonomous delivery vehicle. The centering mechanism uses a compression spring that drives a follower and swashshaft to apply a rotation force on the caster wheels. The rotational force urges the casters frame and wheels to return to a design position. The rotational force increases with the rotational difference between the caster rotational position and the design position.