Crane Slewing Control with Feedforward Speed Compensation
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Solution Overview
Problem
Conventional slewing control devices for cranes face challenges in accurately maintaining the target slewing speed due to variations caused by internal and external factors such as friction, valve spring variations, wind load, and attachment configuration, leading to inaccuracies in slewing operations.
Innovation Solution
A slewing control device that utilizes a controller to generate a corrected command signal based on feedforward control, accounting for variation factors through a neural network to optimize the slewing speed by adjusting the proportional valve command current value, thereby stabilizing the slewing operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional slewing control is used without compensation, then the control system is simple, but the slewing speed cannot reach the target speed due to wind load and other factors
Solution Approach 1:
The controller performs preliminary action by pre-calculating and storing corrected command signals in a lookup table during system initialization or offline processing. During actual operation, the system simply retrieves the pre-computed corrected command signal based on current operating conditions, avoiding the need for complex real-time calculations while achieving accurate slewing speed control despite wind load variations
Solution Approach 2:
The patent introduces an intermediary element - a lookup table storing pre-computed corrected command signals - between the simple proportional valve control and the complex wind load compensation requirements. This intermediary allows the system to achieve accurate speed control without requiring complex real-time computational algorithms, thus resolving the contradiction between precision and complexity
2Reliability
If feedforward control with correction is implemented, then slewing speed accuracy is improved, but the control algorithm becomes more complex
Solution Approach 1:
The controller performs preliminary action by pre-calculating and storing corrected command signals in a lookup table during system initialization or offline processing. During actual operation, the system simply retrieves the pre-computed corrected command signal based on current operating conditions, avoiding the need for complex real-time calculations while achieving accurate slewing speed control despite wind load variations
Solution Approach 2:
The system implements feedback by continuously monitoring actual slewing speed and comparing it with the target speed, then using this information to select appropriate corrected command signals from the lookup table. This feedback mechanism ensures reliable slewing operation while the lookup table structure keeps the real-time control algorithm simple
Data Source
AI summary
A slewing control device is used for a crane that includes an upper slewing body, a lower travelling body, a slewing drive unit, and an attachment. A controller in the slewing control device enables the slewing drive unit to operate based on feedforward control to slew the upper slewing body at a target slewing speed. The controller generates a corrected command signal by correcting a reference command signal set in advance in response to a predetermined target slewing speed, based on information about a variation factor causing the slewing speed to vary. The controller inputs the corrected command signal to the slewing drive unit.