Lift Device Controller Using Orientation Sensors for Stability
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Solution Overview
Problem
Scissor lifts face challenges in safely operating on uneven or sloped surfaces due to the inability to accurately determine and limit the maximum allowable elevation based on pitch and roll angles, leading to potential tipping or rolling hazards.
Innovation Solution
A control system that includes a controller receiving data from orientation sensors to determine the maximum allowable elevation of the platform, limiting the lift assembly's operation to prevent tipping or rolling by restricting further elevation when the platform reaches this limit, and providing alerts to the operator through a user interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the lift assembly is extended to increase platform elevation, then the platform can reach higher work areas, but the risk of tipping or rolling increases on uneven or sloped surfaces
Solution Approach 1:
The controller continuously receives pitch and roll angle data from orientation sensors and dynamically adjusts the maximum allowable elevation limit based on real-time tilt conditions. This feedback mechanism ensures that as the platform elevation increases, the system monitors tilt angles and restricts further elevation if stability thresholds are exceeded, thereby preventing tipping or rolling while allowing maximum safe reach
Solution Approach 2:
The system dynamically determines the maximum allowable elevation limit based on real-time pitch and roll angles rather than using a fixed limit. The controller calculates and updates the elevation threshold adaptively according to current operating conditions, allowing the lift to operate at higher elevations on level ground while automatically reducing the safe elevation limit when tilt angles indicate unstable conditions
2Reliability
If the maximum allowable elevation is determined based on pitch and roll angles, then safety is improved, but the device complexity increases due to additional sensors and control logic
Solution Approach 1:
The controller performs multiple functions: it manages the actuator for lift assembly extension/retraction, receives and processes orientation sensor data, calculates the maximum allowable elevation limit based on pitch and roll angles, and restricts elevation operations when limits are reached. By consolidating these diverse functions into a single control unit, the system achieves enhanced safety without proportionally increasing overall device complexity
Solution Approach 2:
The system replaces complex mechanical safety mechanisms (such as physical limit stops, mechanical interlocks, or multiple redundant safety devices) with an electronic control system that uses orientation sensors and algorithmic calculations to determine and enforce elevation limits. This substitution reduces mechanical complexity while maintaining or improving safety performance
Data Source
AI summary
A lift device includes a lift assembly, a platform, and a controller. The lift assembly is configured to be driven to increase or decrease in length by extension and retraction of one or more actuators. The platform is coupled at an upper end of the lift assembly. The controller is configured to receive a value of a pitch angle and a roll angle of the lift device from an orientation sensor. The controller is further configured to determine a maximum allowable elevation of the platform based on at least one of the value of the roll angle and the value of the pitch angle of the lift device. The controller is further configured to limit operation of the lift assembly based on the maximum allowable elevation of the platform.