Drive Unit Steering via Differential Torque and Passive Chassis

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Solution Overview

Problem

Existing transport systems designed for heavy loads face challenges in maneuverability and stability, particularly when navigating short distances or uneven terrain, as they often require additional motors for steering and are prone to issues with slippage and interference from ground contours.

Innovation Solution

A drive unit with a passive steering mechanism using two independently controlled drive wheels that can apply different torques and rotate in opposite directions, combined with independent suspension and damping systems, allowing for complex steering and navigation without active torque generation, and featuring hard rollers for durability and low wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If additional motors are added for steering, then steering capability is improved, but device complexity increases

Engineering Contradiction:
Improvesteering capabilityVSAvoidnumber of motors
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the steering function with the drive function by using the same drive motors to generate both drive torques and steering torques. The drive motors are controlled to apply different torques to left and right drive wheels, achieving both propulsion and steering simultaneously, thereby eliminating the need for separate steering motors.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The drive motors are designed to perform multiple functions: they provide both the driving force for movement and the differential torques necessary for steering. This multi-functionality reduces the overall system complexity by having single components fulfill multiple roles rather than requiring dedicated components for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If passive steering mechanism is used, then device complexity is reduced, but steering precision deteriorates

Engineering Contradiction:
Improvesteering mechanismVSAvoidsteering precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic steering approach where the steering angle is not fixed but varies continuously based on the differential torques applied to the drive wheels. The passive steering mechanism allows the chassis to rotate freely according to the torque difference, creating a dynamic and adaptable steering system that achieves precision through control algorithms rather than mechanical precision.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback control to maintain steering precision. Sensors detect the actual steering angle and wheel positions, and the control unit adjusts the drive torques accordingly to achieve the desired steering accuracy, compensating for the lack of active mechanical steering control.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If independently controlled drive wheels are used, then maneuverability is improved, but control complexity increases

Engineering Contradiction:
ImprovemaneuverabilityVSAvoidcontrol system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control system utilizes the natural mechanical behavior of the passive steering mechanism to simplify control. By applying differential torques to the drive wheels, the system automatically generates the appropriate steering angle through the passive steering linkage, eliminating the need for complex coordinated control of separate steering and drive systems.

Inventive Principle:
Principle #25Self-service

4Reliability

If hard rollers are used instead of rubber tires, then durability is improved, but friction decreases

Engineering Contradiction:
ImprovedurabilityVSAvoidfriction
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent changes the material parameter of the contact surface from rubber to hard plastic, fundamentally altering the friction characteristics. This parameter change is compensated for by optimizing the drive torque application and utilizing the passive steering mechanism, which maintains adequate traction while achieving the desired durability and wear resistance.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2627553B1Drive unit for a transport system and transport system comprising said drive unit
Publication Date: 2015.07.22 WFT FERTIGUNGSTECHN
  • EP2627553B1 patent drawingFigure 1
  • EP2627553B1 patent drawingFigure 2
  • EP2627553B1 patent drawingFigure 3

AI summary

The invention relates to a drive unit (12) for driving a transport platform (2) of a transport system, comprising a drive mounting (4), a chassis (3), the chassis (3) being mounted in the transport platform (2) by the drive mounting (4) so as to be steerable about a steering axis (5), further comprising at least two driving wheels (6) which are rotatably mounted in the chassis (3), the at least two driving wheels (6) being supplied with different drive torques and/or drive torques that work in the opposite direction and/or opposite rotational directions, the drive unit (1) being designed to steer the transport platform (2) when the at least two driving wheels (6) are supplied with different drive torques.