Spherical Wheel Drive Mounting for Surgical Device Stability
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Solution Overview
Problem
Wheel systems, particularly those with spherical wheels, often experience unintended motion due to backlash and play in their components, leading to instability and potential harm in applications like teleoperated surgical devices, where stability is critical.
Innovation Solution
A spherical wheel drive and mounting system that incorporates rotary bearings, such as ball transfer units, to constrain the spherical wheel for rotation in any direction, combined with a spring-loaded omni wheel to maintain contact and isolate vibrations, thereby reducing instability and unintended motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional casters or spherical wheels are used to allow multi-directional movement, then mobility and ease of operation are improved, but stability and reliability deteriorate due to backlash and play in components
Solution Approach 1:
The patent employs a spherical wheel design that maintains multi-directional mobility while incorporating a rigid spherical structure. The sphere contacts the ground at a single point, allowing rotation in any direction while eliminating the backlash inherent in traditional caster mechanisms with multiple contact points and moving joints.
Solution Approach 2:
The invention removes the traditional caster swivel mechanism entirely, replacing it with a direct spherical wheel mounting. This extraction of the problematic swivel joint eliminates the source of backlash and play, while the spherical wheel itself provides the necessary multi-directional movement capability through its geometry.
2Ease of operation
If omni wheels with multiple small rollers are used to drive the spherical wheel, then ease of operation and mobility are improved, but stability deteriorates due to cogging effects and backlash in the rollers
Solution Approach 1:
The patent replaces the omni wheel mechanism with multiple small rollers with a single continuous belt drive system. The belt wraps around the spherical wheel and is driven by a motor, eliminating the cogging effects and backlash inherent in roller-based omni wheels while maintaining effective drivability.
Solution Approach 2:
The drive system is segmented into a motor, a continuous belt, and multiple contact points on the spherical wheel surface. This segmentation allows the belt to engage the sphere at multiple points simultaneously, providing smooth power transmission without the sequential contact and resulting backlash of roller mechanisms.
3Reliability
If additional stability mechanisms such as retractable feet are added to the wheel system, then stability and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The invention converts the inherent flexibility and play in traditional wheel mechanisms into a rigid, precision-mounted spherical wheel system. By eliminating the need for additional stability mechanisms through the fundamental redesign of the wheel mounting and drive system, the patent achieves stability without increasing complexity.
Solution Approach 2:
The spherical wheel itself serves multiple functions: it provides multi-directional mobility, acts as the driven element, and inherently provides stability through its rigid mounting. This multi-functionality eliminates the need for separate stability mechanisms like retractable feet, reducing overall system complexity.
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 provides enhanced stability and reduced vibrations in wheel systems, ensuring the load remains stationary and secure during medical procedures, improving safety and reducing the need for additional costly stability mechanisms.
Implementation Method 1
a spring element coupled between the omni wheel and base that biases the omni wheel against the spherical wheel and isolates vibrations resulting from rotation of the omni wheel against the spherical wheel
Implementation Method 2
a rotary bearing coupled to the base and contacting a surface of the spherical wheel, where the rotary bearing allows the spherical wheel to rotate
Data Source
AI summary
Implementations relate to a spherical wheel drive and mounting. In some implementations, a wheel mechanism includes a spherical wheel, a base, and a rotary bearing coupled to the base and contacting a surface of the spherical wheel, where the rotary bearing configured to allow the spherical wheel to rotate. The wheel mechanism includes an omni wheel coupled to the base and engaged with a surface of the spherical wheel, and an actuator coupled to the base and to the omni wheel, where the actuator configured to rotate the omni wheel to cause rotation of the spherical wheel.