Transmission Control System Using Motor Position Sensor
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Solution Overview
Problem
The existing transmission control systems using electric motors face challenges in accurately controlling the transmission ratio due to errors in angle measurement, back lash, torsion, and residual stress, leading to deviations in transmission ratio, especially when the vehicle is stopped, and require additional sensors which increase costs and complexity.
Innovation Solution
A transmission control system that includes a motor, actuator, current sensor, position sensor, storage device, and control device with a first estimation unit to estimate the initial transmission ratio using characteristic curves, allowing for accurate control of the transmission ratio even when the vehicle is stopped by correcting initial positions and loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absolute position sensor is provided in the transmission to control the motor, then the controllability of transmission ratio is improved, but the cost and device complexity increase
Solution Approach 1:
The motor's own position sensor is made to serve dual purposes: controlling the motor and measuring the transmission ratio. The control device calculates the transmission ratio by combining the motor's rotational position data with the actuator's displacement data, eliminating the need for separate sensors in the transmission.
Solution Approach 2:
The motor position sensor is extended to perform multiple functions. Instead of being limited to motor control, it is used together with actuator position data to determine the transmission ratio, making the sensor system universal and reducing overall system complexity.
2Reliability
If the motor rotational position is changed while power is turned off, then the correspondence between electric angle and mechanical angle is lost, but storing values in storage device cannot prevent deviance in transmission ratio
Solution Approach 1:
The control device continuously monitors the actual transmission ratio by calculating it from real-time motor position and actuator position data. This feedback mechanism allows the system to detect and correct any deviance between the stored correspondence data and the actual transmission ratio, maintaining accuracy even after power cycles.
Solution Approach 2:
The system pre-calculates and stores the correspondence between motor rotational position and transmission ratio in the form of characteristic curves. These preliminary calculations are stored in the storage device and used as reference data for rapid determination of transmission ratio without requiring complex real-time measurements.
3Force
If gears are mounted to amplify torque in the electric motor, then the torque and speed conditions are satisfied, but back lash and torsion cause deviance between motor and transmission ratio
Solution Approach 1:
The system replaces direct mechanical torque multiplication through gears with an electrical control approach. The motor controller adjusts the motor's output torque directly through electrical control, eliminating the need for gear trains and their associated back lash and torsion errors.
Solution Approach 2:
The control device dynamically adjusts the motor's rotational position and speed parameters to compensate for mechanical imperfections. By changing the control parameters rather than relying on fixed mechanical gear ratios, the system achieves accurate torque control without the precision losses inherent in mechanical gear systems.
Data Source
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AI summary
Provided is a transmission control system that enables more precise control of the transmission ratio. This transmission control system is provided with a motor 3, an actuator 11, a transmission 13, a position sensor 4, a current sensor 5, and a control unit 1. The control unit 1 includes: a drive unit that drives the motor 3 while the vehicle is stopped; and a first estimation unit that estimates the initial transmission ratio, which indicates the transmission ratio when the ignition switch is turned on, on the basis of a rotation position detected by the position sensor 4, a load current detected by the current sensor 5, and a characteristic curve over a period during which the drive unit is operating.