Lifting Desk Obstacle Detection Using Current Change Rate Analysis
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Solution Overview
Problem
Existing lifting desk control methods face challenges in accurately detecting obstacles due to low sensitivity and high costs, particularly with methods relying on abrupt current change detection, mechanical sensors, and three-axis acceleration sensors, which can lead to misjudgments and increased costs.
Innovation Solution
A lifting desk control method involving a motor drive unit, current detection unit, and arithmetic unit that calculates the current change rate over a set time interval, allowing for accurate obstacle detection without additional sensors and minimizing the influence of normal operating conditions, thereby issuing stopping or retreating instructions based on exceeded thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If abrupt current change detection is used for obstacle detection, then the detection method is simple, but the sensitivity for detecting resistance with smaller force is low
Solution Approach 1:
The patent changes the detection parameter from absolute current value to current change rate (dI/dt). By calculating the rate of change of current over time rather than simply comparing current magnitude, the system achieves higher sensitivity in detecting obstacles with smaller resistance forces while maintaining simple implementation through basic arithmetic operations.
2Measurement precision
If mechanical sensors such as piezoelectric sensors or springs are used, then obstacle detection accuracy is improved, but mounting requirements increase and manufacturing becomes difficult
Solution Approach 1:
The patent replaces mechanical sensors (piezoelectric sensors, springs) with an electrical detection method based on current change rate monitoring. This substitution eliminates the need for complex mechanical components and their associated mounting requirements, while achieving comparable or superior detection accuracy through electronic measurement of motor current characteristics.
3Measurement precision
If three-axis acceleration sensors are used, then obstacle detection capability is improved, but cost increases and misjudgment occurs
Solution Approach 1:
The patent utilizes the motor's own current characteristics as the detection signal, making the motor itself serve as the sensing element. This self-service approach eliminates the need for additional expensive sensors like three-axis acceleration sensors, reducing system cost while avoiding the misjudgment issues associated with acceleration-based detection methods.
4Device complexity
If current magnitude judgment is used, then the detection method is simple, but accurate judgment is difficult due to different service conditions under different working conditions
Solution Approach 1:
The patent transitions from static current magnitude comparison to dynamic current change rate analysis. By monitoring how current changes over time (dI/dt) rather than absolute current values, the system adapts to varying working conditions and service loads, achieving accurate obstacle detection regardless of the specific operational context.
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
This method enhances detection sensitivity and reduces costs by focusing on current change rate rather than current magnitude, providing accurate obstacle detection and preventing false alarms during normal operation, while also protecting against overcurrent conditions.
Implementation Method 1
detecting current a at a current time t1 and current b at a time t2 after the current time by a current detection unit
Data Source
AI summary
The invention provides a lifting desk control method including a motor drive unit, a current detection unit and an arithmetic unit. The control method comprises the steps of: detecting current a at the current time t1 and current b at time t2; calculating the current change rate L=(b−a)/(t2−t1); and comparing L with a set value, judging that an obstacle is encountered if the set value is exceeded, and issuing a stopping or retreating instruction to a motor by the motor drive unit. The scheme employed by the invention is to calculate the change rate of current, so judgment is made with higher accuracy and whether an obstacle is encountered is judged with high sensitivity.