3D feature extraction by integrating Laser Scanner and CCD Sensor with IMU for an unmanned Helicopter Platform
2. System Design
In this research, an unmanned helicopter, RPH2, which is made by SUBARU, is used as a
platform as shown in Figure 1. The size of RPH2 is 4.1m length, 1.3m width, and 1.8m height.
Figure 1 RPH2
All the sensors, digital camera, laser scanner, GPS, and IMU are tightly fixed on the unmanned
helicopter. Specifications of the sensors are shown in Table 1. All the sensors are synchronized.
In the experiment, the unmanned helicopter flies about 1.8m/s of speed for acquiring laser point
data with sufficiently fine resolution and sequential digital camera images with sufficient
overlaps. An unmanned helicopter is an ideal platform to measure wide area effectively and
safely.
Table 1 Specification of Sensors
3. Overview
Figure 2 shows the overview of data processing. In this research, the following data are
acquired; base station GPS data, remote station GPS data, IMU data, CCD images, and laser
range data. Though the data are acquired in different frequencies, they are synchronized. At first,
kinematic GPS post processing is conducted. Secondly, processed GPS and IMU are integrated
with Kalman filter. Thirdly, bundle block adjustment of CCD image is made with the support of
GPS/IMU. Finally, GPS/IMU and bundle block adjustment of CCD images are combined for
generating a high precision and time-series position and attitude data. This hybrid positioning
data is used for coordinate conversion of laser range data and construction of digital surface
model. Then, these acquired data are utilized for feature extraction.
Figure 2 Overview of Data Processing
