Variable Deceleration Control for Cargo Swing Suppression
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Solution Overview
Problem
Conventional slow stopping apparatuses for working machines with booms, such as aerial work platforms and cranes, do not adequately consider the flexure of the boom during motion stopping, leading to increased cargo swing and longer stopping times, especially when the boom is extended.
Innovation Solution
A slow stopping apparatus that includes an actuator, a control unit with a first and second slow stopper, a cargo swing predictor, and a switcher, which calculates the cargo swing cycle based on the boom's posture and weight, and predicts the load amplitude to determine the appropriate stopping time, using either the first or second slow stopper to minimize cargo swing while shortening the stopping time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the motion speed of the boom is reduced at a constant acceleration to stop the working machine, then the cargo swing is suppressed, but the stopping time is increased
Solution Approach 1:
The patent applies dynamics by making the braking deceleration variable rather than constant. The control unit changes the braking deceleration based on the boom's motion speed, using higher deceleration when speed is high and lower deceleration when speed is low, thereby optimizing the stopping process to suppress cargo swing while minimizing stopping time.
Solution Approach 2:
The patent changes the parameter of braking deceleration from a fixed constant value to a variable value that depends on the boom's motion speed. By dynamically adjusting the deceleration parameter according to the current motion state, the system achieves both cargo swing suppression and reduced stopping time.
2Productivity
If the motion speed of the boom is high, then the productivity is improved, but the flexure of the boom is increased when stopping suddenly
Solution Approach 1:
The patent applies preliminary action by calculating the cargo swing cycle time in advance based on the boom's posture and cargo weight, and using this pre-calculated information to determine the appropriate braking deceleration before the actual stopping occurs. This allows the system to prepare for the stopping process and avoid sudden stops that would cause excessive boom flexure.
Solution Approach 2:
The patent uses feedback by continuously monitoring the boom's motion speed and adjusting the braking deceleration accordingly. The control unit receives feedback on the current motion state and modifies the braking parameters in real-time, preventing excessive deceleration that would cause boom flexure while maintaining productivity.
3Stability of the object's composition
If the cargo swing cycle time is taken to carry out stop regardless of the motion speed, then the cargo swing is suppressed, but the stopping time is increased when the motion speed is low
Solution Approach 1:
The patent applies dynamics by making the stopping time variable rather than fixed. The control unit adjusts the stopping time based on the boom's motion speed, using longer stopping times when speed is high (to suppress cargo swing) and shorter stopping times when speed is low (to maintain productivity), thereby optimizing the balance between cargo swing suppression and 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
The apparatus effectively suppresses cargo swing and reduces stopping time by accurately predicting the cargo swing cycle and load amplitude, allowing for proper switching between slow stoppers to maintain an allowable load amplitude, thereby improving operational efficiency and safety.
Implementation Method 1
a first slow stopper which calculates a cargo swing cycle of the cargo and takes a time in a half of the cargo swing cycle to brake and stop the actuator
Implementation Method 2
a cargo swing predictor which predicts whether a load amplitude of the cargo would exceed an allowable value
Implementation Method 3
an actuator which operates the working machine, a control unit which controls a driving motion of the actuator
Implementation Method 4
the flexure of the boom can approximate to that of a cantilever and an amount δ of the flexure of the cantilever is expressed in the following Equation 1... the force F is an inertial force (F=ma) of the cargo supported on the boom
Data Source
AI summary
Provided is a slow stopping apparatus for a working machine which can shorten a stopping time while suppressing a cargo swing. The slow stopping apparatus includes a first slow stopper 21 which calculates a cargo swing cycle T and takes a time T1 in a half of the cargo swing cycle T to stop an actuator 10 when a stop signal is input, a second slow stopper 22 which takes a shorter time T2 than the time T1 in the half of the cargo swing cycle T to stop the actuator 10, a cargo swing predictor 23 which predicts whether a load amplitude A would exceed an allowable value, and a switcher 24 which switches the first slow stopper 21 and the second slow stopper 22 in accordance with prediction of the cargo swing predictor 23. It is possible to suppress a cargo swing in stop of a motion of the working machine, thereby shortening a time required for stopping the motion of the working machine.