Rotary Input Knob Layout Without Internal Wires
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Solution Overview
Problem
Existing input devices with strain gauges inside a rotary mechanism face complexity in wire arrangement and configuration, restricting rotation angle and hindering size reduction due to the presence of wires within the mechanism.
Innovation Solution
An input device design featuring a rotary mechanism without internal wires, utilizing magnetorheological fluid and air-core coils to apply driving torque and braking force, with a non-magnetic supporting portion to reduce magnetic attraction and cogging torque, and a strain gauge to detect strain for controlling braking force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain gauge is attached to the drive shaft inside the rotary mechanism, then rotation direction can be detected, but wire arrangement becomes complicated and device size cannot be reduced
Solution Approach 1:
The strain gauge is extracted from the internal rotary mechanism and relocated to the external stationary housing. This allows the strain gauge to remain functional for detecting rotation direction while eliminating the need for wires to pass through the rotary mechanism, thereby simplifying the internal structure and enabling size reduction.
Solution Approach 2:
The drive shaft serves as an intermediary mechanical element that transmits rotational motion from the rotary member to the electromagnetic brake. By positioning the strain gauge on the drive shaft's external surface, the system detects rotation direction through the drive shaft's deformation without requiring internal wire routing through the rotating components.
2Measurement precision
If wires are laid inside the rotary mechanism for strain gauge signal extraction, then rotation direction detection is enabled, but the configuration becomes complicated and rotation angle is restricted
Solution Approach 1:
The strain gauge and its wiring are extracted from the internal rotary mechanism and relocated to the external stationary housing. This eliminates the constraint that wires would impose on the rotation angle, allowing the rotary member to rotate freely without wire entanglement or tension limitations.
3Measurement precision
If the rotary mechanism includes internal wires for strain gauge connection, then rotation detection is possible, but size reduction in drive axis direction becomes difficult
Solution Approach 1:
The strain gauge is extracted from the internal rotary mechanism and mounted on the external stationary housing. This removal of internal components eliminates the space required for wire routing and strain gauge installation within the compact rotary assembly, enabling further size reduction in the drive axis direction.
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 simplifies the rotary mechanism, reduces device size, and provides variable tactile sensations by controlling driving and braking torque, while minimizing backlash and magnetic attraction, resulting in a more compact and operable input device.
Implementation Method 1
The brake-applying unit includes magnetorheological fluid, a brake-applying coil that applies a magnetic field to the magnetorheological fluid
Implementation Method 2
the torque-applying unit include a plurality of torque-applying coils arranged in a circumferential direction of an outer circumferential surface of the supporting portion, and a magnet that faces the plurality of torque-applying coils with an interval
Data Source
AI summary
An input device includes a fixed unit, a rotary member rotatably supported by the fixed unit, a rotation-detecting unit that detects a rotation angle of the rotary member, a brake-applying unit that applies a braking force to the rotary member, a torque-applying unit that applies a driving torque to the rotary member, and a control unit that controls the brake-applying unit and the torque-applying unit. The brake-applying unit includes magnetorheological fluid, a brake-applying coil that applies a magnetic field to the magnetorheological fluid, a shaft to which braking torque that changes with viscosity of the magnetorheological fluid is applied, and a transmission gear provided on the shaft and that is in mesh with a gear provided on the rotary member. The shaft is positioned on an outer side with respect to the rotary member in a radial direction of the rotary member.