Curved Gimbal Link Geometry for Smooth Low-Inertia Haptic Control
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Solution Overview
Problem
Existing gimbal assemblies in master control input devices for telesurgical systems face challenges with high friction, perceptible irregularities in motion, undesirable haptic sensations, and increased inertia due to the addition of powerful actuators, leading to restrictive and non-fluid input control and haptic feedback for operators.
Innovation Solution
A control assembly with a first and second link, where the actuator axis and joint shaft define an offset angle greater than 0 degrees and less than 90 degrees, and a curved portion of the second link housing, along with a motor and gear transmission system, reduces inertia and provides smoother, weightless operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If powerful actuators are added to counteract inertia and provide gravity compensation, then the weightless sensation and gravity compensation improve, but the mass and inertia of the gimbal links increase, leading to more restrictive control
Solution Approach 1:
The patent applies curved geometry to the gimbal link, specifically making the link housing cylindrical rather than traditional L-shaped rectangular geometry. This curvature allows the actuator to be positioned closer to the joint shaft while maintaining structural integrity, reducing the moment arm and thereby decreasing the inertia that the actuator must counteract.
Solution Approach 2:
The patent introduces an offset angle between the actuator axis and the joint shaft axis, creating a three-dimensional configuration rather than a planar one. This spatial arrangement allows the actuator to exert torque more efficiently by optimizing the mechanical advantage, reducing the required actuator power and associated mass.
2Ease of operation
If traditional L-shaped gimbal link geometry is used, then the actuator can be positioned for gravity compensation, but the friction and motion irregularities increase, leading to perceptible haptic sensations
Solution Approach 1:
The cylindrical geometry of the gimbal link housing provides smoother surfaces for rotational movement compared to the sharp corners and flat surfaces of L-shaped links. This curved geometry reduces friction points and eliminates the perceptible haptic irregularities that occur during rotation, resulting in smoother motion.
3Device complexity
If the actuator axis is aligned with the joint shaft axis, then the structure is simplified, but the ability to counteract gravitational torque is reduced
Solution Approach 1:
The patent positions the actuator axis at an offset angle relative to the joint shaft axis, utilizing the third dimension to create an optimal torque arm. This angular offset allows the actuator to generate sufficient gravitational compensation torque while maintaining a compact structure, balancing complexity and force requirements.
Data Source
AI summary
A control input assembly including a first link and a second link. A link housing extends from a second link first end portion to a second link second end portion. The second link first end portion is coupled to a first link second end portion via a joint shaft. An actuator is mounted within the link housing and the actuator defines an actuator axis. The actuator is configured to exert a torque on the joint shaft. The actuator axis and a rotational axis of the join shaft defines an offset angle, the offset angle being between about 20 degrees and 70 degrees.