Rotary Actuator Assembly With Damped Haptic Knob Control
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Solution Overview
Problem
Existing rotary actuator assemblies for infotainment systems in vehicles face challenges in providing an improved feel at the knob, as current solutions require large motors for adequate torque and suffer from free play and vibration issues, which affect the haptic experience.
Innovation Solution
A rotary actuator assembly comprising a gear assembly with a rotary oil damper and an optical rotation detection device, which allows a small electric motor to generate desired haptic effects by controlling torque as a function of displacement, using a gear ratio to enhance packaging and reduce free play, and an optical rotation detection system to minimize vibrations and oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a DC motor is used to provide haptic effect in both rotational directions, then the haptic effect can be provided bidirectionally, but the motor becomes relatively large and heavy
Solution Approach 1:
The patent replaces a purely mechanical bidirectional brake system with an electric motor control system. The DC motor's direction of rotation is controlled electronically through software, eliminating the need for a large bidirectional mechanical brake while achieving the same bidirectional haptic effect capability.
Solution Approach 2:
The patent changes the control parameter from mechanical brake engagement to electrical motor control. By controlling the direction of current to the DC motor, the system achieves bidirectional rotation and haptic feedback without requiring a large mechanical structure, thus reducing motor size and weight.
2Force
If a gear assembly is used to increase torque at the knob, then the applicable torque is increased, but the device complexity increases
Solution Approach 1:
The gear assembly serves multiple functions: it provides torque multiplication to increase force at the knob, enables speed reduction for better control, and integrates with the encoder system for precise position feedback. This multi-functionality justifies the added complexity by delivering superior haptic control.
Solution Approach 2:
The gear assembly acts as an intermediary between the electric motor and the knob, transforming the motor's high-speed low-torque output into low-speed high-torque output suitable for haptic feedback at the knob, while also providing a mechanical interface for the encoder.
3Loss of information
If an incremental encoder is used to detect rotation information, then direction and speed information is obtained, but the measurement precision may be insufficient for eliminating oscillation
Solution Approach 1:
The incremental encoder provides continuous feedback on the knob's position, speed, and direction to the control unit. This feedback loop allows the control algorithm to detect oscillations and adjust motor control in real-time, improving measurement precision through active correction rather than relying solely on encoder resolution.
Solution Approach 2:
The patent replaces mechanical precision elements (such as precision gears or cam profiles) with an electronic sensing and control system. The incremental encoder combined with software-based haptic control achieves precise oscillation elimination through electronic feedback, potentially offering better precision than purely mechanical solutions.
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 a refined haptic experience with reduced free play and vibrations, allowing for a compact design and improved motor control, enabling adjustable torque characteristics and enhanced feel at the knob.
Implementation Method 1
an optical rotation detection device for detecting direction, speed and/or angle of rotation of the knob and/or of the electric motor. The optical rotation detection device is detecting the rotation of an element on the shaft
Implementation Method 2
The gear assembly includes a rotary oil damper damping the rotation of the knob
Data Source
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AI summary
A rotary actuator assembly comprises a knob and an electric motor for providing a haptic effect at the knob and/or for driving the knob. The electric motor comprises a shaft, a gear assembly rotationally coupling the knob to the shaft of the electric motor, the gear assembly including a rotary oil damper damping the rotation of the knob. The rotary actuator assembly further comprises an optical rotation detection device for detecting direction, speed and/or angle of rotation of the knob and/or of the electric motor, wherein the optical rotation detection device is detecting the rotation of an element on the shaft.