AGV Cart-Towing Turn Control to Reduce Caster Friction

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Solution Overview

Problem

Automated guided vehicles (AGVs) face difficulties in smoothly turning during autonomous travel with towed carts due to increased frictional resistance, which hinders movement and can cause slipping, especially when handling heavier loads.

Innovation Solution

The AGV system employs a controller that gradually shifts to autonomous traveling mode, allowing the robot to turn while moving forward, reducing frictional force by controlling the speed and rotational velocity of its wheels, and uses a caster configuration that can swivel and roll, enabling smooth turning by adjusting the turning radius and applying torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the AGV shifts from line trace traveling to autonomous traveling to disconnect the basket cart away from the guide path, then the operator burden is reduced, but the frictional resistance increases making it difficult to turn the basket cart

Engineering Contradiction:
Improveoperator burdenVSAvoidfrictional resistance
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The AGV performs preliminary actions by gradually shifting from line trace traveling to autonomous traveling mode before reaching the disconnection position. This gradual transition allows the AGV to build up momentum and reduce the frictional resistance when turning the basket cart, making the turning operation smoother and more efficient.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The AGV dynamically adjusts its traveling mode during the approach to the disconnection position. By transitioning from line trace traveling to autonomous traveling while moving forward, the system optimizes the balance between guide path following and maneuvering capability, reducing the frictional resistance during basket cart turning.

Inventive Principle:
Principle #15Dynamics

2Force

If the basket cart is turned from the stopped state, then the turning resistance increases due to frictional force, but turning while moving forward reduces this resistance

Engineering Contradiction:
Improveturning resistanceVSAvoidforward speed
Core Design Contradiction:
ForceVSSpeed

Solution Approach 1:

The AGV performs preliminary actions by gradually shifting from line trace traveling to autonomous traveling mode before reaching the disconnection position. This gradual transition allows the AGV to build up momentum and reduce the frictional resistance when turning the basket cart, making the turning operation smoother and more efficient.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The AGV dynamically adjusts its traveling mode during the approach to the disconnection position. By transitioning from line trace traveling to autonomous traveling while moving forward, the system optimizes the balance between guide path following and maneuvering capability, reducing the frictional resistance during basket cart turning.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the AGV uses drive wheels to rotate and move the basket cart, then the frictional force can inhibit wheel rotation or cause slipping, but controlling speed and rotational velocity reduces these issues

Engineering Contradiction:
Improvebasket cart movementVSAvoidwheel slipping
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The AGV performs preliminary actions by gradually shifting from line trace traveling to autonomous traveling mode before reaching the disconnection position. This gradual transition allows the AGV to build up momentum and reduce the frictional resistance when turning the basket cart, making the turning operation smoother and more efficient.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The AGV controller monitors and adjusts the drive wheel rotation based on the basket cart's movement status. By providing feedback control on wheel rotation and speed, the system prevents wheel slipping and ensures reliable basket cart turning during the transition to autonomous traveling mode.

Inventive Principle:
Principle #23Feedback

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 enables the AGV to smoothly turn and disconnect carts without manual intervention, reducing operator burden and improving efficiency even with heavier loads by minimizing frictional resistance during the turning process.

Implementation Method 1

the resistance to the turning increases due to the frictional force between casters of the basket cart and a floor surface

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3879373B1Autonomous traveling device and autonomous traveling control method
Publication Date: 2023.02.08 RICOH CO LTD
  • EP3879373B1 patent drawingFigure 1
  • EP3879373B1 patent drawingFigure 2
  • EP3879373B1 patent drawingFigure 3

AI summary

An autonomous traveling device (1) configured to tow a cart (2) including a caster (23), which swivels around an axis (CP) perpendicular to a rotation axis (SP) of a wheel (23a), includes a drive wheel (71); a self-position detection unit (111) to detect a position of the autonomous traveling device (1); a forward travel control unit (112) to drive the drive wheel (71) to move the autonomous traveling device (1) forward; a backward travel control unit (115) to drive the drive wheel (71) to move the autonomous traveling device (1) backward; and a turning control unit (113) to drive the drive wheel (71) to turn the autonomous traveling device (1). In response to a detection that the autonomous traveling device (1) towing the cart (2) is at a turning position, the forward travel control unit (112) and the turning control unit (113) drive the drive wheel (71) so that the autonomous traveling device (1) turns by a predetermined angle while moving forward or backward. Based on a determination that the autonomous traveling device (1) towing the cart (2) is at a moving-back position, the backward travel control unit (115) drive the drive wheel (71) to move the autonomous traveling device (1) backward to a target position.