Power Seat Positioning Control for Sensor Pulse Accuracy
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Solution Overview
Problem
Existing positioning devices for electric power seats in vehicles suffer from inaccurate positioning due to erroneous detection of the movable part's position by the rotation sensor, caused by operations within the movable range that are too short or subject to external forces, leading to deviations in the set seat positions during memory power seat reproduction.
Innovation Solution
The positioning device incorporates deceleration and learning control mechanisms to stop the DC motor at a target rotation position midway between the rising and falling edges of the rotation sensor's output pulse, using inertial, braking, and forced braking modes to prevent erroneous pulse generation, and employs learning control to adjust stop timings for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the motor stops at the end of the movable range, then the positioning is completed, but the rotation sensor generates erroneous pulses due to reverse rotation or inertia, causing position detection errors
Solution Approach 1:
The control device applies a preliminary reverse rotation command before the motor reaches the target position to counteract the inertial reverse rotation that would otherwise occur after stopping. This preliminary anti-action prevents the rotation sensor from generating erroneous pulses by ensuring the motor stops with minimal residual momentum in the correct direction.
Solution Approach 2:
The control device performs preliminary action by detecting the motor's inertial reverse rotation behavior during initial operation and learning the characteristics of this reverse rotation. This learned information is then used to adjust subsequent positioning operations, allowing the system to compensate for inertial effects and prevent erroneous pulse generation.
2Productivity
If the user operates the seat within the movable range for a short duration, then the operation is completed quickly, but the motor may stop before the rotation sensor generates a pulse, causing position detection errors
Solution Approach 1:
The control device uses feedback from the rotation sensor to continuously monitor the motor's rotational position and detect whether pulses are being generated during operation. When short-duration operations cause the motor to stop before generating a pulse, the feedback mechanism detects this condition and triggers a compensation operation to ensure accurate position detection.
Solution Approach 2:
The control device changes operational parameters by adjusting the motor's rotation speed and stopping criteria based on the detected operation duration. For short-duration operations, the system modifies the stopping conditions to ensure the motor continues rotating long enough for the rotation sensor to generate at least one pulse, thereby maintaining position detection accuracy.
3Ease of operation
If external forces act on the seat during operation, then the seat moves to the desired position, but the motor stops at an incorrect position relative to the rotation sensor pulses, causing positioning errors
Solution Approach 1:
The control device dynamically adjusts the motor's operation in response to external forces acting on the seat. By continuously monitoring the rotation sensor pulses and comparing them with the motor's commanded position, the system detects discrepancies caused by external forces and applies corrective rotation to realign the motor position with the actual seat position, maintaining positioning accuracy despite external disturbances.
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 approach ensures highly accurate positioning control by preventing erroneous pulse generation, maintaining the original seat position accuracy even after multiple repetitions of memory power seat operations, and allowing for precise reproduction of user-set seat positions.
Implementation Method 1
a Hall element 202 arranged in a fixed portion to detect the magnetic field generated by the magnet as an electric signal
Implementation Method 2
an actuator connected to a moving body and composed of a DC motor, a speed reduction mechanism
Data Source
AI summary
A positioning device contains an actuator composed of a DC motor, a deceleration mechanism, and a single-phase rotation sensor for detecting the amount of rotational displacement of the deceleration mechanism, and an electronic control unit that electrically drives the DC motor. The electronic control unit learns the time required for the motor to stop after turning off the power, and decelerates and controls the DC motor to stop at a target rotation stop position, which is approximately midway between the rising edge and the falling edge of the output pulse of the rotation sensor.