2831 © 2014 ISIJ
ISIJ International, Vol. 54 (2014), No. 12, pp. 2831–2836
An Imaging Algorithm for Burden Surface with T-shaped MIMO
Radar in the Blast Furnace
Xin FU,
1,2)
*
Xianzhong CHEN,
1,2)
Qingwen HOU,
1,2)
Zhengpeng WANG
1,2)
and Yixin YIN
1,2)
1) School of Automation & Electrical Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian
Zone, Beijing, 100083 China. 2) Key Laboratory of Advanced Control for Iron and Steel Process, Ministry of Education,
China, No. 30 Xueyuan Road, Haidian Zone, Beijing, 100083 China.
(Received on April 1, 2014; accepted on August 7, 2014)
This paper proposed a new near-field imaging algorithm for Blast Furnace (BF) burden surface imaging.
The algorithm was applied in a novel T-shaped MIMO radar. In the process of beam synthesis focusing,
the proposed algorithm does precise phase compensation to realize the equiphase surface. It avoids inter-
polation, reduces the computational complexity, and is convenient for data batch processing concurrently,
which greatly improves the efficiency of operations and enhances the real-time performance. Simulation
results and the on-line test result demonstrate the effectiveness and high operational efficiency of the pro-
posed MIMO radar imaging method which has great potential in BF burden surface imaging.
KEY WORDS: T-shaped MIMO radar; burden surface; blast furnace.
1. Introduction
Near-field imaging has been extremely concerned for its
widespread application in many civilian military and bio-
medical applications. Present microwave imaging radars
being applied for blast furnace burden surface imaging are
single radar,
1–3)
distributed array radar,
4,5)
mechanically-
scanned radar
6)
and phased array radar.
7)
In these four
radars, we have to say the advantage and disadvantage of the
phased array radar on burden surface detection. It employs
a group of antennas to realize the antenna beam electric
scanning by phase shifter. Imaging resolution and real-time
performance can meet the requirements of industrial BF
production. But the high angular resolution is attained by
increasing the size and cost of the radar.
In recent years, an emerging radar system is explored
with the MIMO concept.
8)
With the introduction of space-
diversity and multiplexing techniques, MIMO radar can use
less actual antenna elements to form a virtual antenna array
and obtain multiplied communication channels and free-
dom.
9)
MIMO radar for imaging applications can enhance
the imaging resolution and reduce the radar cost significant-
ly. So far, neither MIMO radar used in BF industry nor
research for MIMO radar suitable for harsh environment
and rough surface imaging is reported.
Many types of microwave imaging algorithms such as the
range migration algorithm (RD),
10)
the chirp scaling algo-
rithm (CS),
11)
the omega-k algorithm (
ω
-k)
12)
and the wave-
number domain algorithm are based on a plane wave which
are suitable for far-field imaging and the resolutions are lim-
ited by classical radar uncertainty principle. These limita-
tions make it difficult to use these conventional algorithms
for BF burden surface imaging. How to obtain a more real-
istic and high-resolution burden surface images in harsh
environment is also a hot topic. The near-field imaging algo-
rithm has been well developed. The tomographic imaging
algorithm
13)
is successfully used in the near-field imaging.
This algorithm is suitable for wide angle imaging, but it
needs summation in the frequency dimension. Also, it is too
slow for real time imaging when the span of the angle is
large in azimuth. A two-dimensional nonuniform fast Fou-
rier transformation (NUFFT) is applied to the near-field
scattered data.
14)
However the algorithm is only suitable for
the narrow angular case. The fast cyclical convolution
algorithm
15)
is also able to create near-field SAR images of
the target. In order to save computing time, the author
16)
presents a near-field linear SAR algorithm based on the use
of a focusing operator defined by the measurement geome-
try. The authors
17)
studied imaging system based on the
combination of ultra-wideband (UWB) transmission,
MIMO array, and SAR. However, the imaging algorithm
also utilized the range migration which needs 3-D Stolt
interpolation and a 3-D IFFT.
The above all near-field imaging algorithms need interpo-
lation for echo data in order that the spherical wave can
convert into planar wave. The interpolation is not only time-
consuming, but also can cause certain deviation on the edge
of the target. Aiming at the problem that these imaging
algorithms suffer heavy computational burden and poor
real-time capability, a new highly computing efficiency near-
field imaging method is proposed based on the assumption
of spherical wave. In the process of beam synthesis focusing,
the proposed algorithm does precise phase compensation to
* Corresponding author: E-mail: fxzn2006@163.com
DOI: http://dx.doi.org/10.2355/isijinternational.54.2831