Force-Feedback Input Knob Using Worm Gear and Spring Assist
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Solution Overview
Problem
Existing force generation input devices require large motors to transmit a sense of force to the operator, leading to increased device size due to the need for high torque generation.
Innovation Solution
The input device incorporates a base member, motor, worm gear, first gear, rotor, elastic member, and change amount detection unit, allowing for reduced motor size by utilizing a worm gear and elastic members to generate and control the sense of force applied to the operator, with the motor driving the worm gear to assist or limit the restoring force, thereby reducing the required torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a motor generates large torque to transmit sense of force to the operator, then the sense of force transmission is effective, but the device size increases
Solution Approach 1:
The patent segments the force generation function into two parts: the motor generates only the necessary torque to move the worm gear against spring force, while the elastic member (spring) provides the majority of the force feedback to the operator. This segmentation allows the motor to be much smaller than in conventional designs where the motor must generate all the force feedback torque directly.
Solution Approach 2:
The worm gear acts as an intermediary mechanism between the motor and the rotor. It translates the motor's rotational motion into linear motion of the movable member, which then interacts with the elastic member. This intermediary arrangement allows the motor to operate at lower torque while still achieving effective force feedback through the spring mechanism.
2Volume of stationary object
If the motor size is reduced to minimize device volume, then space efficiency improves, but the torque generation capability decreases
Solution Approach 1:
The patent introduces dynamic elements including the movable member that translates rotational motion to linear motion, and the elastic member that dynamically provides restoring force. The worm gear's axial movement coupled with the spring's elastic deformation creates a dynamic force multiplication effect, allowing a small motor to generate sufficient force feedback through the compliant mechanism rather than requiring high static torque capability.
Solution Approach 2:
The patent changes the operational parameters of the force feedback system by introducing compliance through the elastic member. Instead of relying on high motor torque, the system uses the spring constant and preload force of the elastic member to generate the primary force feedback. The motor only needs to overcome the spring force and provide small additional torque for precise control, dramatically reducing the required motor size.
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
This configuration enables a compact input device that provides a range of force sensations to the operator while minimizing the motor's size and torque requirements, improving space efficiency and reducing the overall device size.
Implementation Method 1
The elastic member is configured to generate urging force in a direction in which the movement of the movement member is suppressed in accordance with a movement amount of the movement member
Implementation Method 2
The worm gear is configured to be rotated by the rotation shaft and attached to the rotation shaft so as to be movable in an axial direction of the rotation shaft
Data Source
AI summary
An input device includes a base member, a motor, a rotation shaft, a worm gear, a first gear, a rotor, a movement member, an elastic member, a change amount detection unit, and a controller. The rotation shaft is rotated by the motor. The worm gear is rotated by the rotation shaft. The first gear is rotatable and engaged with the worm gear. The rotor is rotatable relative to the base member, includes a second gear engaged with the first gear, and is rotated by an operator. The movement member is moved as the worm gear is moved. The elastic member generates urging force. The change amount detection unit detects a change amount of a state that is changed in accordance with the movement of the movement member. The controller performs drive control for the motor to change a sense of force applied to the operator.