Forklift Distance Sensor Positioning Under a Carried Pallet
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Solution Overview
Problem
Autonomous forklifts face challenges in detecting objects in the forward direction when holding a pallet due to the pallet obstructing the laser sensor's scanning path.
Innovation Solution
A forklift design with a distance sensor movable in the height direction, restricted by a mechanism that switches its position between a storage position and a measurement position using a guide mechanism and a restriction mechanism, allowing detection of objects even when holding a pallet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the laser sensor is fixed to the fork for detecting pallet position, then the sensor structure is simple, but the sensor cannot detect objects in the forward direction when the fork holds a pallet because the pallet blocks the scanning path
Solution Approach 1:
The distance sensor is made movable relative to the fork through a guide mechanism, allowing it to dynamically change its position between a storage position (when fork is low) and a measurement position (when fork is elevated). This dynamic positioning enables the sensor to avoid the pallet obstruction by being positioned below the pallet when needed, while maintaining detection capability when the fork is raised.
Solution Approach 2:
The solution introduces vertical dimension movement to resolve the horizontal obstruction problem. Instead of moving the sensor horizontally to avoid the pallet, the mechanism moves the sensor vertically along the guide member, allowing it to position itself below the pallet's lower surface when the fork holds the pallet, thus clearing the scanning path.
2Ease of operation
If the distance sensor is positioned low to measure objects when the fork holds a pallet, then forward detection is enabled, but the sensor may contact the floor and suffer damage when the fork is in lower positions
Solution Approach 1:
The distance sensor's position is dynamically adjusted based on the fork's height. When the fork is elevated to the second height range, the sensor moves to the measurement position below the pallet for forward detection. When the fork is lowered to the first height range, the sensor automatically returns to the storage position spaced from the floor, preventing contact damage.
Solution Approach 2:
The system uses the fork's height position as feedback to control the sensor's position. The restriction mechanism responds to the fork's vertical position, automatically switching the sensor between storage and measurement positions based on whether the fork is in the first or second height range, thereby protecting the sensor while enabling detection when needed.
3Ease of operation
If a mechanism is introduced to move the distance sensor between storage and measurement positions, then detection capability is improved, but the device complexity increases
Solution Approach 1:
The guide mechanism allows the distance sensor to move vertically along the guide member, enabling the sensor to switch between storage and measurement positions. This simple vertical guiding structure provides the necessary positional flexibility without requiring complex actuation systems.
Solution Approach 2:
The restriction mechanism automatically switches the sensor between positions based on the fork's height, using the system's own operational state (fork position) to control the sensor positioning. This self-service approach eliminates the need for separate control systems or electronic components, reducing overall complexity.
4Productivity
If the fork is kept at a low position for efficient operation, then productivity is improved, but the distance sensor cannot detect objects in the forward direction because it is blocked by the pallet
Solution Approach 1:
The distance sensor dynamically positions itself relative to the fork's height. When the fork is in the second height range (elevated), the sensor moves to the measurement position below the pallet, enabling forward detection while maintaining the fork's operational height for productivity.
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
Enables reliable detection of objects in the forward direction while holding a pallet, preventing sensor contact with the floor and avoiding damage, achieved through a cost-effective mechanism without requiring electronic components for position switching.
Implementation Method 1
a laser sensor is used for detecting a position of a fork insertion opening of a pallet. The laser sensor detects a shape of the pallet by performing scanning over a predetermined range on a front side in a horizontal direction with a laser beam.
Data Source
AI summary
A forklift capable of recognizing a state on a front side even when holding a pallet is provided. A forklift includes: a fork movable in a height direction; a distance sensor held by the fork to be relatively movable with respect to the fork in the height direction, the distance sensor measuring a distance to an object existing in a forward direction; and a restriction mechanism restricting a movement of the distance sensor in a downward direction of the height direction when the fork is placed within a first height range from a floor surface to a first height. The distance sensor is: placed at a storage position spaced from the floor surface when restricted by the restriction mechanism; and placed at a measurement position lower than a lower surface of a pallet held by the fork when the fork is placed within a second height range equal to or higher than the first height.