Servo Electric Crane Positioning at Low Speed to Reduce Vibration
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Solution Overview
Problem
Conventional electric cranes are limited in operation speed, causing vibrations and potential object drops when moving to hang objects, as they cannot operate below 5 Hz, posing safety hazards in various industrial environments.
Innovation Solution
An electric crane equipped with a permanent magnet servo motor, encoder, and a control unit that allows for adjustable speed operation between 0.1 Hz and 5 Hz, enabling precise control through a manually operated lever with multiple switches and a pulse signal generator, allowing the crane to move at desired speeds and positions based on user requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the drive device operates at conventional speeds (5 Hz to 50 Hz), then the crane can move the hanging assembly quickly, but the hanging assembly vibrates and objects may drop when moving to hang positions
Solution Approach 1:
The patent applies dynamics by making the operating speed of the drive device adjustable rather than fixed. The permanent magnet servo motor enables continuous speed adjustment from 0.1 Hz to 50 Hz, allowing the system to adapt its speed to different operational requirements. This resolves the contradiction by enabling slow operation (0.1-5 Hz) when precision and safety are critical, and fast operation (5-50 Hz) when speed is prioritized.
Solution Approach 2:
The patent changes the speed parameter from a fixed range (5-50 Hz) to an adjustable range (0.1-50 Hz). By introducing the ability to vary the operating frequency parameter, the system can select appropriate speeds for different tasks: very low speeds (0.1-5 Hz) for precise positioning and hanging operations to minimize vibration, and higher speeds for rapid movement between positions.
2Ease of operation
If the drive device is limited to 5 Hz to 50 Hz operation, then the system structure remains simple, but the crane cannot operate at very slow speeds required for precise positioning
Solution Approach 1:
The patent replaces conventional mechanical drive systems with a permanent magnet servo motor controlled by a programmable logic controller (PLC). This substitution enables precise speed control and positioning through electronic control rather than mechanical means, achieving high precision positioning (slow speeds 0.1-5 Hz) while maintaining relatively simple system architecture through standardized control components.
Solution Approach 2:
The patent implements feedback control through the encoder connected to the permanent magnet servo motor and the PLC-based control system. The encoder provides position feedback, and the PLC processes this information to adjust motor operation, enabling precise positioning control. This feedback mechanism allows the system to achieve high precision without excessive mechanical complexity.
3Productivity
If the crane operates at higher speeds (5 Hz to 50 Hz), then productivity increases, but vibrations occur causing objects to drop during positioning
Solution Approach 1:
The patent applies periodic action by using very slow, controlled movement cycles (0.1-5 Hz) during critical positioning and hanging operations. This extremely slow periodic motion allows the system to maintain productivity through efficient high-speed operation (5-50 Hz) during non-critical phases, while eliminating vibration during the critical slow positioning phase where objects are being hung.
Solution Approach 2:
The patent uses dynamic speed adjustment to resolve the productivity-safety contradiction. The permanent magnet servo motor allows the system to operate at high speeds (5-50 Hz) for rapid movement between positions to maintain productivity, then switch to very low speeds (0.1-5 Hz) during positioning and hanging operations to eliminate vibration and ensure safety, optimizing both productivity and safety throughout the operational cycle.
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 electric crane can move at very slow speeds (0.1 Hz to 5 Hz) with precise control, reducing vibrations and ensuring safe object handling by allowing vertical and horizontal movement within 1 mm to 2 mm distances, enhancing operational safety and flexibility.
Implementation Method 1
The drive device of the body is a permanent magnet servo motor
Implementation Method 2
the drive device has an encoder electrically connected on an end thereof opposite to the permanent magnet servo motor
Implementation Method 3
The operation lever has a pulse signal generator rotatably controlled by the rotary hand wheel to generate pulse signals
Data Source
AI summary
An electric crane contains: a body and an electrical box. The body includes a drive device, a roller, a lift assembly, and a hanging assembly. The electrical box is electrically connected with an operation lever configured to be manually controlled by a user, and the operation lever has multiple switches. The drive device is a permanent magnet servo motor and has an encoder. The electrical box includes a control unit electrically connected with the encoder to feed back a detected position of a rotator of the permanent magnet servo motor and to compare whether an operating instruction of the permanent magnet servo motor matches with a rotating speed of the permanent magnet servo motor. The operation lever has a rotary hand wheel. The operation lever has a pulse signal generator. The pulse signal generator is electrically connected with the electrical box.