Direct-Drive Wheel Torque Limit Detection Before Slip Onset
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Solution Overview
Problem
Existing solutions for improving vehicle stability and road handling primarily focus on reactive measures after wheel slippage or deviations have occurred, lacking a method to predict the safety limit and adjust propulsion parameters in real-time to prevent slip.
Innovation Solution
An arrangement for determining a maximum allowable torque at a driving wheel of an electric motor vehicle, which includes two or more driving wheels, torque detecting means, rotational speed sensors, and a computational unit that adjusts output torque. The system applies transient changes in drive torque to determine rotational speed differences, calculates the slip ratio, and constructs a slip curve to determine the maximum allowable torque before wheel slip occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reactive torque adjustment is used after wheel slip detection, then wheel slippage can be corrected, but vehicle stability cannot be proactively maintained
Solution Approach 1:
The system performs preliminary determination of maximum allowable torque by continuously monitoring wheel rotational speed and calculating slip ratios before actual wheel slip occurs. The computational unit predicts the safety limit and adjusts propulsion parameters proactively, rather than waiting for slip to happen and then reacting.
Solution Approach 2:
The system implements continuous feedback by monitoring wheel rotational speed parameters, calculating slip ratios in real-time, and comparing them against determined maximum allowable torque values. This feedback loop enables dynamic adjustment of drive torque to maintain operation within safe limits.
2Measurement precision
If transient torque changes are applied to determine slip ratio, then accurate maximum torque determination is achieved, but measurement precision requirements increase
Solution Approach 1:
The system applies transient torque changes that exceed normal operating torque to deliberately induce measurable wheel slip. By applying excessive torque temporarily, the system generates sufficient slip signal to accurately determine the slip ratio and calculate maximum allowable torque, then returns to normal operation.
Solution Approach 2:
The system replaces complex mechanical slip detection mechanisms with computational analysis of rotational speed parameters. The computational unit calculates slip ratios from sensor data through mathematical processing, substituting mechanical complexity with computational intelligence.
Data Source
Figure 1~2
AI summary
An arrangement for determining a parameter representing a maximum allowable torque at a driving wheel (1) of an electric motor (7) vehicle, comprising two or more driving wheels (1), a torque detecting means (4), rotational speed detection sensors (5) for each driving wheel (1), a computational unit (6) capable of adjusting output torque at each driving wheel (1), wherein the driving wheels (1) are each driven individually by electric motors (7) which can each be operated separately by an inverter controlling torque output of the motor, and wherein the computational unit (6) triggers a transient change in the drive torque, at least one driving wheel (1), and wherein the rotational speed parameters which are determined in said driving wheels (1) are compared with each other in the computational unit (6) in the sense of identifying slip, wherein said electric motors (7) are direct drive motors, without implementation of gearing and transmission elements, wherein said rotation speed detection sensors (5) are designed to detect rotational differences of equal or less than 1 degree and wherein said computational unit (6) is capable of determining several points on a slip curve.