Real-Time <i>In Situ</i> Laser Ranging Based on Online Echo Waveform Fitting

Xie, Xinhao; Xu, Lijun; Wang, Zining; Li, Xiaolu

doi:10.1109/jsen.2019.2924706

Cited by 22 publications

(10 citation statements)

References 23 publications

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“…To obtain the point cloud in real time, some on-line methods implemented on field programmable gate arrays (FPGAs) were proposed. The existing online processing methods include the maximum estimation method, the matched filter and interpolation method [15], and the Gauss-Newton (GN) method [16]. The maximum estimation method measures the distance by obtaining the location of the maximum amplitudes of the emitted pulse and laser echoes [17].…”

Section: Introductionmentioning

confidence: 99%

“…The GN has a high range measurement rate of 285.7 kHz and a ranging precision of 1.7 cm for a laser echo with an SNR of 36.6 dB [18]. However, the existing GN method can only obtain one distance from a laser echo [16]. When there are multiple targets at the transmission of the emitted laser pulse, the laser echo is a superposition of the laser pulses scattered from each target.…”

Section: Introductionmentioning

confidence: 99%

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A multi-target on-line ranging method based on matrix sparsification and a division-free Gauss–Jordan solver

Zhang

Xie

et al. 2021

Meas. Sci. Technol.

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To improve the on-line laser-ranging performance of light detection and ranging (LiDAR), the run time and resource consumption of the commonly used Gauss-Newton method need to be considered under the condition of high-frequency laser echo scattered from multiple targets. Limited by insufficient hardware processing units and the requirement of increased measurement speed, a multi-target laser ranging based on matrix sparsification and a division-free Gauss-Jordan solver implemented on a field programmable gate array is proposed. A Jacobian matrix sparsification method is used to reduce the number of multiplication operations in the coefficient matrix and constant vector calculations, thereby reducing hardware resources and time costs. In order to increase the hardware implementation efficiency, a division-free Gauss-Jordan elimination method is used to quickly solve linear equations. The Vivado-based simulation results show that the amount of hardware resources, such as look-up tables, flip-flops and digital signal processor (DSP) are reduced by 34.5%, 35.7% and 27.3%, respectively, and the time cost is reduced by 3 µs (750 clock cycle @250 MHz) in the case of five iterations, satisfying the real-time requirements for a measurement rate of 45.45 kHz at most. Experimental results show that the proposed method maintains comparable performance of point extraction ability, ranging precision and accuracy, which are 100.0%, 1.78 cm and 0.62

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A multi-target on-line ranging method based on matrix sparsification and a division-free Gauss–Jordan solver

Zhang

Xie

et al. 2021

Meas. Sci. Technol.

Self Cite

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show abstract

“…One solution [9], [10] use Caruana's method, which has low computation complexity and thus fast speed at the cost of accuracy loss. Another solution use complex optimization methods such as Gauss-Newton method [11] and Levenberg-Marquardt method [12] to improve accuracy, but has high computation workload and thus needs high-performance processor to meet the real-time requirement. However, laser ranging systems used on the spaceborne platforms have the cost, size, and energy limits.…”

Section: Introductionmentioning

confidence: 99%

“…Gauss-Newton method was implemented on FPGA for nonlinear curve fitting in a real-time ranging system [11]. The Gauss-Newton method requires the matrix inversion, which is typically implemented by solving linear equations.…”

Section: Introductionmentioning

confidence: 99%

Peak Detection Based on FPGA Using Quasi-Newton Optimization Method for Femtosecond Laser Ranging

et al. 2020

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Dual femtosecond laser ranging (DFLR) is an enabling absolute distance measurement technique which is advantageous of high measurement precision, fast update rate, and large unambiguous range. Peak detection, which requires repeated online solution of nonlinear curve fitting, is a key module of the DFLR system and its performance affects the accuracy and real-time of the ranging system. In addition, for long baseline measurements based on satellite-borne platforms, the DFLR system has requirements in high integration, low cost, and small size. This paper presents a peak detection implementation on a field-programmable gate array (FPGA) that employs a Broyden-Fletcher-Goldfarb-Shanno (BFGS) method to handle nonlinear curve fitting. FPGA is used to explore the possibilities of parallel architecture for the acceleration of peak detection, and realize the miniaturization of the system. The detailed architecture design of the peak detection module using BFGS method (PD-BFGS) and two hardware structures are proposed. Then, the PD-BFGS module is applied to a DFLR system and evaluated with experiments on the absolute distance measurement. The experimental results indicate that the PD-BFGS based on FPGA effectively reduces the peak detection error by 42.81%, compared with the peak detection module using Caruana's method. For the DFLR system, the ranging error is reduced by 63.63% and the real-time updating of the ranging results is guaranteed. INDEX TERMS BFGS-QN method, femtosecond laser ranging, field-programmable gate array (FPGA), nonlinear curve fitting, peak detection.

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“…The use of LIDAR based system is becoming significant in the design of autonomous automobiles and 3D virtual reconstruction of surrounding with very high precision [1]- [7]. To fulfill the high accuracy and resolution of distance measurement, multi-stage TDC structure is preferred for wide dynamic range.…”

Section: Introductionmentioning

confidence: 99%

A Design of 6.8 mW All Digital Delay Locked Loop With Digitally Controlled Dither Cancellation for TDC in Ranging Sensor

et al. 2020

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This paper presents a design of 6.8 mW all digital delay locked loop (ADDLL) with digitally controlled dither cancellation (DCDC) for time to digital converter (TDC) in ranging sensors. ADDLL uses the accumulator (ACC) to control the delay of digitally controlled delay line (DCDL) during phase locking which utilizes less power and area as compared to analog delay locked loop (DLL). In the lock state, the ACC value dithers due to the closed loop operation. A digital controller is proposed to detect the lock state, performs dither cancelation and selects the optimum ACC value for controlling the delay of the replica DCDL for TDC operation. It helps the jitter reduction in the ADDLL. Additionally, it provides robustness against glitches, false locking and unlocking in a noisy environment. The ADDLL peak to peak jitter and RMS jitter at 625 MHz are 6.5 ps and 1.2 ps respectively. The ADDLL including DCDC is implemented on 0.18 µm CMOS technology with an operational range of 350∼900 MHz. It consumes only 6.8 mW at 625 MHz power with 1.8 V power supply. The area utilization is 0.06 mm 2. INDEX TERMS All digital delay locked loop (ADDLL), digital controller, jitter, light detection and ranging (LIDAR), time to digital converter (TDC).

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Real-Time In Situ Laser Ranging Based on Online Echo Waveform Fitting

Cited by 22 publications

References 23 publications

A multi-target on-line ranging method based on matrix sparsification and a division-free Gauss–Jordan solver

A multi-target on-line ranging method based on matrix sparsification and a division-free Gauss–Jordan solver

Peak Detection Based on FPGA Using Quasi-Newton Optimization Method for Femtosecond Laser Ranging

A Design of 6.8 mW All Digital Delay Locked Loop With Digitally Controlled Dither Cancellation for TDC in Ranging Sensor

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