Differential Drive Propulsion Control for Split-Friction Wheel Slip

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Solution Overview

Problem

Existing methods for controlling vehicle motion in heavy-duty vehicles with open differential drive arrangements struggle to efficiently manage wheel slip, leading to unpredictable behavior, loss of tractive force, and energy inefficiency, especially in uneven friction conditions.

Innovation Solution

A method for controlling propulsion in heavy-duty vehicles with differential drive arrangements, involving the determination of nominal shaft slip and adjustment based on wheel speed differences to achieve a target shaft slip, thereby improving traction and maintaining vehicle motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If torque is applied to drive wheels to generate tractive force, then vehicle propulsion is achieved, but excessive wheel slip occurs leading to loss of tractive force and unpredictable vehicle behavior

Engineering Contradiction:

Improvetractive forceVSAvoidvehicle behavior predictability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The control system continuously monitors wheel speeds and shaft speed, calculating actual shaft slip in real-time. Based on the calculated shaft slip value, the system adjusts the drive shaft torque to maintain optimal traction while preventing excessive wheel slip. This closed-loop feedback control ensures reliable and predictable vehicle behavior during propulsion.

Inventive Principle:

Principle #23Feedback

2Power

If torque is applied to drive wheels to generate tractive force, then vehicle propulsion is achieved, but energy efficiency decreases due to excessive wheel slip

Engineering Contradiction:

Improvetractive forceVSAvoidenergy efficiency

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The system uses real-time feedback from wheel speed sensors and shaft speed measurements to calculate actual shaft slip. The controller adjusts drive shaft torque based on this calculated slip value, optimizing energy utilization by preventing excessive wheel slip that would waste energy. This ensures efficient energy conversion from the power source to vehicle motion.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If open differential drive arrangement is used to power both wheels on driven axle, then vehicle propulsion is enabled, but in split friction conditions one wheel spins faster than the other resulting in sub-optimal propulsion

Engineering Contradiction:

Improvepropulsion capabilityVSAvoidpropulsion efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The control system independently monitors the speed of each wheel and the shaft speed, calculating the actual shaft slip based on these measurements. This feedback mechanism enables the system to detect and respond to split friction conditions by adjusting the drive shaft torque to optimize the utilization of both wheels, preventing one wheel from spinning excessively while the other underperforms.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the drive shaft torque parameter based on the calculated actual shaft slip value. By changing this critical parameter in real-time according to road friction conditions, the system optimizes propulsion efficiency in split friction scenarios, ensuring both wheels contribute effectively to vehicle motion.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If shaft speed is controlled to reduce wheel slip differences, then traction is enhanced and vehicle stability is maintained, but control system complexity increases

Engineering Contradiction:

Improvevehicle stabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control system calculates actual shaft slip using feedback from existing wheel speed sensors and shaft speed measurements. This calculated slip value is then used to adjust drive shaft torque, maintaining vehicle stability without requiring additional complex hardware. The system leverages available sensor data through computational processing to achieve reliable control.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Instead of using complex mechanical differential locks or additional mechanical components to control wheel slip, the system substitutes a computational approach. The control unit calculates actual shaft slip from sensor data and uses electronic control to adjust torque distribution, replacing mechanical complexity with computational simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12208799B2Method for controlling propulsion of a heavy-duty vehicle

Publication Date: 2025.01.28 VOLVO TRUCK CORP

AI summary

A method for controlling propulsion of a heavy-duty vehicle, where the heavy-duty vehicle comprises a differential drive arrangement arranged in connection to a drive axle with a left wheel and a right wheel is provided. The method includes determining a nominal shaft slip corresponding to a desired wheel force to be generated by the drive axle wheels, wherein the nominal shaft slip is indicative of a difference between a current vehicle velocity and a vehicle velocity corresponding to the shaft speed, determining a difference between a speed of the left wheel and a speed of the right wheel, adjusting the nominal shaft slip in dependence of a magnitude of the wheel speed difference to a target shaft slip, and controlling the shaft speed based on the target shaft slip.