Steering Column Height Adjuster PWM Control for Constant Speed
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Solution Overview
Problem
Steering column height adjustments in motor vehicles result in varying adjustment speeds and sounds due to weight forces, causing annoyance to the driver.
Innovation Solution
An electrically adjustable steering column method using pulse width modulation (PWM) to control the electric motor, ensuring constant adjustment speed by varying the duty cycle, and determining the load condition through initialization and periodic measurements to maintain consistent sound development during height adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the steering column height is adjusted using a simple electric motor without control optimization, then the structure remains simple, but the adjustment speed varies and produces inconsistent sounds
Solution Approach 1:
The control system dynamically adjusts the PWM duty cycle based on the detected load condition and adjustment direction to maintain constant adjustment speed. The controller modifies motor power delivery in real-time, transitioning from static to dynamic control to compensate for varying gravitational loads during raising and lowering operations.
Solution Approach 2:
The system uses feedback from load condition detection (current measurement) to adjust the PWM duty cycle. The controller continuously monitors motor current, determines the load state, and modifies the control signal accordingly, creating a closed-loop control system that maintains consistent adjustment speed despite external force variations.
2Speed
If the electric motor is controlled with constant power during height adjustment, then the control is simple, but the adjustment speed varies due to weight forces
Solution Approach 1:
The system changes the electrical parameter (PWM duty cycle) based on the mechanical load condition. By detecting current consumption and determining load state, the controller adjusts the voltage parameter delivered to the motor, optimizing energy usage while maintaining constant speed during both raising and lowering operations.
Solution Approach 2:
The control system operates in periodic cycles: detect load condition, determine adjustment direction, calculate appropriate PWM duty cycle, and execute motor control. This periodic measurement and adjustment approach ensures consistent speed while optimizing energy consumption throughout the adjustment range.
3Object-affected harmful factors
If the height adjuster operates without load condition detection, then the device complexity is low, but the sound development is inconsistent and annoying
Solution Approach 1:
The height adjuster system performs self-diagnosis by measuring its own current consumption to determine load conditions. The motor controller uses the motor's own electrical characteristics (current draw) to infer mechanical load state and adjust control parameters, eliminating the need for external sensors or complex measurement systems.
Solution Approach 2:
The system replaces potential mechanical load sensors with electrical measurement (current detection). By using electrical parameters (current consumption) to infer mechanical load conditions, the system achieves accurate load detection without adding mechanical complexity, maintaining consistent sound quality through electrical control adjustments.
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 method provides a uniform and pleasant sound experience for the driver by maintaining constant adjustment speed and sound during both raising and lowering of the steering wheel, accounting for load changes and manufacturing tolerances.
Implementation Method 1
a height adjuster including an electric motor
Implementation Method 2
the control is effected by pulse width modulation, wherein by varying a duty cycle of the pulse width modulation (PWM duty cycle) the electrical voltage is adapted
Implementation Method 3
The worm shaft is in engagement with a worm wheel
Implementation Method 4
the electric motor drives a threaded rod engaged with a spindle nut, wherein a rotational movement of the threaded rod is converted into a translational movement of the spindle nut
Implementation Method 5
a lever is held pivotably in a hinge axis on the holder and in a hinge axis on the guide bracket, and the electric motor effects pivoting of the guide bracket by the lever
Data Source
AI summary
A method of operating a steering column of a motor vehicle, which includes a height adjuster including an electric motor and a controller to control the electric motor to raise and lower along an adjustment path of a steering assembly connected to the steering column. The control is effected by pulse width modulation and, by varying a duty cycle of the pulse width modulation, an electrical voltage is adapted in such a way that the raising and/or lowering is effected over an adjustment path at a constant adjustment speed.