Lifting Vehicle Control Device for Dynamic Overload Compensation
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Solution Overview
Problem
Existing vehicle control systems for telescopic lifting arms, which use open-loop control and hydraulic circuits, often result in unstable operations due to sudden arm movements causing dynamic overloads and potential loss of adherence or overturning, especially during sharp maneuvers.
Innovation Solution
An automatic electronic control device that processes signals from a joystick and uses feed-forward control to estimate the kinetic energy of the lifting arm's vibrations, generating a compensated signal by convolving pulses to reduce or eliminate oscillations, adapting to varying load weights and arm extensions, and accounting for the hydraulic circuit's response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open-loop control system is used for lifting arm operation, then operator can control the arm movement, but sudden commands cause dynamic overloads and vehicle instability
Solution Approach 1:
The control system introduces feedback by continuously monitoring the actual arm position and comparing it with the commanded position. The error signal is then used to generate compensating control actions that eliminate overshoot and oscillations, thereby maintaining vehicle stability while preserving operator control capability.
Solution Approach 2:
The system performs preliminary action by predicting the arm's natural oscillations and applying compensating control signals in advance. The controller anticipates the oscillatory behavior and pre-empts it with counteracting forces, preventing dynamic overloads before they occur.
2Force
If hydraulic power circuit is used for arm actuation, then arm can be moved with sufficient force, but system exhibits oscillations and natural frequencies that compromise stability
Solution Approach 1:
The system addresses mechanical vibration by utilizing the hydraulic circuit's inherent damping properties and adding controlled vibration countermeasures. The controller introduces anti-phase vibrations to cancel out unwanted oscillations, thereby reducing the arm's natural frequency effects while maintaining sufficient actuation force.
Solution Approach 2:
The control system acts as an intermediary between the hydraulic power circuit and the lifting arm. It mediates the interaction by filtering out oscillatory components and transmitting only the necessary positional control signals, thereby decoupling the force-generating capability of the hydraulic system from the stability requirements of the arm movement.
3Productivity
If sharp maneuvers are executed, then work can be performed efficiently, but vehicle may lose adherence or overturn
Solution Approach 1:
The control system applies preliminary anti-action by detecting sharp maneuver commands and pre-empts them with stabilizing control signals. When the operator inputs a sharp maneuver, the controller immediately generates compensating forces to counteract the resulting dynamic overloads, preventing loss of adherence before it occurs.
Solution Approach 2:
The system provides beforehand cushioning by introducing damping control actions that cushion against the harmful effects of sharp maneuvers. The controller applies controlled resistance and stabilization forces that cushion the impact of sudden movements, protecting the vehicle from overturning while allowing efficient work operations.
Data Source
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AI summary
A lifting vehicle (1) comprises a mobile lifting arm (3), first measuring means (16) for measuring at least one working parameter of the arm (3) and a control device (13) receiving an input signal (SJ) and configured for deriving the value of the natural frequency of vibration of the arm (3) as a function of the load and of the working range and for determining a control signal (SV) for actuating the arm (3). In particular, the signal (SV) is defined at least partially by the convolution of the input signal (SJ) with a plurality of pulses having a time delay between one another and an amplitude defined as a function at least of the first natural frequency.