Servo Lifting Control via Force Sensing and Stability Switching
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Solution Overview
Problem
Conventional lifting device control systems require operators to handle a control lever separately from the load, preventing them from simultaneously controlling and handling the load effectively, especially when lifting or positioning it.
Innovation Solution
A control system that includes a force-measuring means, a first controller for computing servo motor direction and speed, and a switching mechanism to ensure stable operation, allowing the operator to control the load's direction and speed by applying a controlling force via a rope wound by a servo motor, with a second controller activated when the load touches the ground to prevent unwanted movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control lever is located apart from the load, then the control system can independently control the servo motor, but the operator cannot simultaneously hold the load and handle the control lever
Solution Approach 1:
The control system merges the control function directly with the load by enabling the operator to apply force directly to the load. The force applied by the operator on the load is detected by the force measuring means, and the servo motor automatically adjusts its operation based on this force, eliminating the need for a separate control lever and allowing the operator to simultaneously hold and control the load.
2Productivity
If the servo motor rotates at high speed to lift the load quickly, then productivity increases, but the load may touch the ground causing instability and unwanted movement
Solution Approach 1:
The system uses force measuring means to continuously monitor the force applied to the load. When the load touches the ground and the measured force drops below a predetermined threshold, the switching means automatically switches from the first controller to the second controller. The second controller is specifically designed to maintain stability under this condition, preventing unwanted movement while allowing high-speed operation during normal lifting.
Solution Approach 2:
The control system dynamically adapts its behavior based on the operating condition. The switching means enables the system to transition between two different control modes: the first controller for normal high-speed lifting operations, and the second controller for stability maintenance when the load contacts the ground. This dynamic switching allows the system to optimize for speed during lifting while ensuring stability during ground contact.
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
Enables operators to handle and control loads in desired directions and speeds while preventing unintended movement when the load touches the ground, enhancing operational efficiency and safety.
Implementation Method 1
a means for measuring a force... measures the force that is applied at the lower part of the rope. The total force is caused by a force for controlling that is generated by the operator, the mass of the load, and the acceleration of the load.
Implementation Method 2
The rope is wound up and down by the rotation of the servo motor in the forward or the reverse direction... controls the rotation of a servo motor so that an operator can move a load in a direction and at a speed that he or she desires
Data Source
AI summary
A control system for a lifting device in which a load moves up or down or maintains its position by a rope that is wound up or down by the rotation of a servo motor. It includes a device for measuring a force, a first controller, a second controller and a switching device. A total force that is applied at the lower part of the rope caused by a force for controlling, the mass of the load, and the acceleration of the load is measured. The first controller, based on the measured force computes the direction and the speed of the servo motor, and outputs a signal to it. The second controller determines a stable condition using Popov's stability criterion. The switching device replaces the first controller with the second controller when the value that is measured by the measuring device becomes less than a threshold.