Lidar Mirror Control for Uniform Point Cloud Density
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Solution Overview
Problem
Conventional laser radar systems using three-dimensional laser scanners often result in uneven point cloud data density due to non-constant mirror rotation speeds and distances between data points, leading to parts with high and low density in the acquired data.
Innovation Solution
A measurement apparatus with a mirror system rotated by dual motors about horizontal and vertical axes, controlled by a processor to maintain constant rotational speeds and adjust data density, ensuring consistent point cloud data acquisition by varying the number of rotations and rotational speeds of the motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mirror rotates at high speed to improve measurement productivity, then the measurement speed increases, but the rotational speed becomes non-constant causing uneven point cloud data density
Solution Approach 1:
The system dynamically adjusts the rotational speed of the mirror based on real-time feedback from the rotational speed detection unit. The control unit modifies the drive signal to the driving unit to maintain constant rotational speed despite load variations, ensuring uniform point cloud data density while maintaining high measurement speed
Solution Approach 2:
A rotational speed detection unit continuously monitors the mirror's rotational speed and feeds this information back to the control unit. The control unit compares the detected speed with the target speed and adjusts the drive signal accordingly, creating a closed-loop control system that maintains constant rotational speed and uniform data density
2Stability of the object's composition
If the motor rotational speed is reduced below its performance limit to achieve constant speed rotation, then the rotational speed becomes constant, but the measurement productivity decreases
Solution Approach 1:
Instead of operating the motor at a fixed low speed, the system dynamically controls the motor speed to maintain constancy within its performance capabilities. The control unit continuously adjusts the drive signal to keep the rotational speed constant at the desired level, maximizing productivity while ensuring stability
Solution Approach 2:
The system changes the operational parameters of the motor by adjusting the drive signal characteristics (voltage, current, or pulse width) to achieve the desired constant rotational speed. This parameter optimization allows the motor to operate at higher speeds while maintaining constancy, thereby improving productivity
3Device complexity
If the distances between adjacent point cloud data are made non-constant to simplify motor control, then the control complexity decreases, but the measurement precision deteriorates
Solution Approach 1:
The control unit uses feedback from the rotational speed detection unit to maintain constant rotational speed, which ensures constant distances between adjacent point cloud data. This feedback mechanism achieves high measurement precision without significantly increasing control complexity, as the system automatically compensates for speed variations
Solution Approach 2:
The system optimizes the drive signal parameters to achieve constant rotational speed at the lower limit value. By carefully selecting and adjusting these parameters, the system achieves uniform point cloud data density with minimal increase in control complexity
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 solution achieves high-density point cloud data with consistent distances between points, reducing unevenness and enhancing the accuracy of shape measurement by maintaining constant rotational speeds and adjusting motor control parameters.
Implementation Method 1
a mirror configured to irradiate an object with scanning light and to reflect reflected light from the object
Implementation Method 2
a first driving unit configured to rotate the mirror about a first axis parallel to a horizontal direction
Implementation Method 3
a second driving unit configured to rotate the mirror about a second axis parallel to a vertical direction
Implementation Method 4
a light source configured to emit laser light, a light receiver configured to receive reflected light from an object irradiated with the laser light, and a controller configured to measure a distance to the object using time of flight
Data Source
AI summary
A measurement apparatus includes a mirror configured to irradiate an object with scanning light and to reflect reflected light from the object, a first driving unit configured to rotate the mirror about a first axis parallel to a horizontal direction, a second driving unit configured to rotate the mirror about a second axis parallel to a vertical direction, and a processor configured to control the first driving unit and the second driving unit and to acquire data on a shape of the object based on the reflected light. The processor acquires information about control of the second driving unit based on a lower limit value of a rotational speed of the second driving unit, which allows the second driving unit to rotate at a constant speed, and a target value of density of the data.