Crane Deceleration Control for Payload Sway Suppression
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Solution Overview
Problem
Existing crane control methods fail to completely suppress payload sway during deceleration, leading to longer stopping distances and safety risks, particularly when operated by unskilled operators.
Innovation Solution
A second velocity pattern is applied to cancel out the superposition of payload sways resulting from initial control, using acceleration and deceleration patterns to control crane operations, thereby reducing the distance and time required for safe stopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the rate of change of crane velocity is increased to reduce stopping distance, then the stopping distance is shorter, but the payload sway amplitude becomes larger
Solution Approach 1:
The patent applies periodic acceleration and deceleration actions at specific timing intervals (one-half period or one-quarter period of the sway) to counteract payload sway. This periodic action allows the crane to achieve shorter stopping distance while suppressing payload sway through rhythmically timed control inputs rather than continuous braking.
Solution Approach 2:
The patent applies preliminary braking action before the payload sway reaches its maximum amplitude, and applies reverse braking at predetermined timing intervals. This preliminary and timed action prevents excessive sway development while achieving the stopping objective, resolving the contradiction between stopping distance and sway amplitude.
2Stability of the object's composition
If the velocity change time is extended to suppress payload sway, then the payload sway is suppressed, but the stopping distance becomes longer
Solution Approach 1:
Instead of extending velocity change time continuously, the patent uses periodic acceleration and deceleration pulses at specific timing intervals. This approach suppresses payload sway effectively while maintaining a relatively short overall stopping distance by utilizing rhythmic control actions rather than prolonged braking.
Solution Approach 2:
The patent employs feedback mechanisms to detect payload sway state and automatically adjusts the timing and magnitude of braking actions. This feedback control enables effective sway suppression while optimizing stopping distance by applying control forces only when and where needed based on real-time sway conditions.
Data Source
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AI summary
A crane is provided in which a stopping distance is reduced to improve safety while a payload sway occurring when the crane is stopped is suppressed. The crane includes: a velocity command generation section that generates a movement velocity command for a horizontal movement device; and a crane control section that moves the horizontal movement device according to the velocity command. And, the velocity command generation section generates: a deceleration pattern v1 in which deceleration is performed from the moment a stop operation start signal is received; and an acceleration and deceleration pattern v2 in which acceleration and deceleration are performed to cancel out a payload sway x01 resulting from superposition of a payload sway x0 at the time of the stop operation start and a payload sway x1 occurring when the horizontal movement device is driven according to the deceleration pattern v1. The horizontal movement device is driven according to the deceleration pattern v1 from the time of the stop operation start, and then the horizontal movement device is driven according to the acceleration and deceleration pattern v2 such that a time at which the amount of payload sway of the payload sway x01 reaches a maximum and a center time of the acceleration and deceleration pattern v2 coincide with each other.