scholarly journals The Reference Path Tracer

2021 ◽  
pp. 161-187
Author(s):  
Jakub Boksansky ◽  
Adam Marrs
Keyword(s):  
Reference Path

Study on optical confocal probe based on time difference measurement with no reference path

2006 ◽  
Author(s):  
Yuming Fan ◽  
Shuzhong Zhao ◽  
Junfeng Ren ◽  
Guoxiong Zhang
Keyword(s):  
Time Difference ◽  
Reference Path ◽  
Difference Measurement

scholarly journals An automated driver based on convergent vector fields

2002 ◽  
Vol 216 (4) ◽  
pp. 329-347 ◽  
Author(s):  
T J Gordon ◽  
M C Best ◽  
P J Dixon
Keyword(s):  
Vector Field ◽  
Feedback Control ◽  
Field Analysis ◽  
Driver Model ◽  
Cruise Control ◽  
Essential Information ◽  
Mass Centre ◽  
Reference Path ◽  
Driving Task ◽  
Specific Implementation

This paper describes a new general framework for the action of an automated driver (or driver model) to provide the control of longitudinal and lateral dynamics of a road vehicle. The context of the problem is assumed to be in high-speed competitive driving, as in motor racing, where the requirement is for maximum possible speed along a track, making use of a reference path (racing line) but with the capacity for obstacle avoidance and recovery from large excursions. While not necessarily representative of a human driver, the analysis provides worthwhile insight into the nature of the driving task and offers a new approach for vehicle lateral and longitudinal control; it also has applications in less demanding applications such as Advanced Cruise Control systems. As is common in the literature, the driving task is broken down into two distinct subtasks: path planning and local feedback control. In the first of these tasks, an essentially geometric approach is taken here, which makes use of a vector field analysis. At each location x the automated driver is to prescribe a vector w for the desired vehicle mass centre velocity; the spatial distribution and global properties of w( x) provide essential information for stability analysis, as well as control reference. The resulting vector field is considered in the context of limited friction and limited mass centre accelerations, leading to constraints on ∇ w. Provided such constraints are satisfied, and using suitable adaptation of w( x) when required, it is shown that feedback control can be applied to guarantee stable asymptotic tracking of a reference path, even under limit handling conditions. A specific implementation of the method is included, using dual non-linear SISO (single-input single-output) controllers.

scholarly journals Review and Comparison of Path Tracking Based on Model Predictive Control

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1077 ◽  
Author(s):  
Guoxing Bai ◽  
Yu Meng ◽  
Li Liu ◽  
Weidong Luo ◽  
Qing Gu ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Real Time ◽  
Predictive Control ◽  
Path Tracking ◽  
Error Model ◽  
The Real ◽  
Time Performance ◽  
Reference Path ◽  
Reference Velocity ◽  
Positioning Errors

Recently, model predictive control (MPC) is increasingly applied to path tracking of mobile devices, such as mobile robots. The characteristics of these MPC-based controllers are not identical due to the different approaches taken during design. According to the differences in the prediction models, we believe that the existing MPC-based path tracking controllers can be divided into four categories. We named them linear model predictive control (LMPC), linear error model predictive control (LEMPC), nonlinear model predictive control (NMPC), and nonlinear error model predictive control (NEMPC). Subsequently, we built these four controllers for the same mobile robot and compared them. By comparison, we got some conclusions. The real-time performance of LMPC and LEMPC is good, but they are less robust to reference paths and positioning errors. NMPC performs well when the reference velocity is high and the radius of the reference path is small. It is also robust to positioning errors. However, the real-time performance of NMPC is slightly worse. NEMPC has many disadvantages. Like LMPC and LEMPC, it performs poorly when the reference velocity is high and the radius of the reference path is small. Its real-time performance is also not good enough.

scholarly journals A Smart Many-Core Implementation of a Motion Planning Framework along a Reference Path for Autonomous Cars

Electronics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 177 ◽  
Author(s):  
Gianpiero Cabodi ◽  
Paolo Camurati ◽  
Alessandro Garbo ◽  
Michele Giorelli ◽  
Stefano Quer ◽  
...  
Keyword(s):  
Real Time ◽  
Graphics Processing Units ◽  
Data Communication ◽  
Computational Effort ◽  
Random Trees ◽  
Sequential Algorithm ◽  
Original Algorithm ◽  
Reference Path ◽  
Autonomous Cars

Research on autonomous cars, early intensified in the 1990s, is becoming one of the main research paths in automotive industry. Recent works use Rapidly-exploring Random Trees to explore the state space along a given reference path, and to compute the minimum time collision-free path in real time. Those methods do not require good approximations of the reference path, they are able to cope with discontinuous routes, they are capable of navigating in realistic traffic scenarios, and they derive their power from an extensive computational effort directed to improve the quality of the trajectory from step to step. In this paper, we focus on re-engineering an existing state-of-the-art sequential algorithm to obtain a CUDA-based GPGPU (General Purpose Graphics Processing Units) implementation. To do that, we show how to partition the original algorithm among several working threads running on the GPU, how to propagate information among threads, and how to synchronize those threads. We also give detailed evidence on how to organize memory transfers between the CPU and the GPU (and among different CUDA kernels) such that planning times are optimized and the available memory is not exceeded while storing massive amounts of fuse data. To sum up, in our application the GPU is used for all main operations, the entire application is developed in the CUDA language, and specific attention is paid to concurrency, synchronization, and data communication. We run experiments on several real scenarios, comparing the GPU implementation with the CPU one in terms of the quality of the generated paths and in terms of computation (wall-clock) times. The results of our experiments show that embedded GPUs can be used as an enabler for real-time applications of computationally expensive planning approaches.

scholarly journals 3DOF Adaptive Line-Of-Sight Based Proportional Guidance Law for Path Following of AUV in the Presence of Ocean Currents

2019 ◽  
Vol 9 (17) ◽  
pp. 3518 ◽  
Author(s):  
Fengxu Liu ◽  
Yue Shen ◽  
Bo He ◽  
Junhe Wan ◽  
Dianrui Wang ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Path Following ◽  
Lyapunov Theory ◽  
Line Of Sight ◽  
Average Error ◽  
Drift Angle ◽  
Reference Path ◽  
Guidance Law ◽  
Look Ahead ◽  
Three Degrees Of Freedom

In order to achieve high-precision path following of autonomous underwater vehicle (AUV) in the horizontal plane, a three degrees-of-freedom adaptive line-of-sight based proportional (3DOFAPLOS) guidance law is proposed. Firstly, the path point coordinate system is introduced, which is suitable for the conversion of an arbitrary path. Then, the appropriate look-ahead distance is obtained by an improved adaptive line-of-sight (ALOS) according to three degrees-of-freedom (3DOF), including the cross-track error, the curvature of reference path, and the forward speed. Moreover, combining three degrees-of-freedom ALOS (3DOFALOS) with proportional guidance law, the desired heading is calculated considering the drift angle. 3DOFAPLOS has two functions: in the convergence stage, 3DOFALOS plays a leading role, making AUV converge to the path more quickly and smoothly. In the guidance stage, proportional guidance law plays a major role in effectively resisting the influence of drift angle and making AUV sail along the reference path. If the path is curved, 3DOFALOS makes contributions in both stages, adjusting look-ahead distance in real time with respect to curvature. The stability of the designed closed system is proved by Lyapunov theory. Both simulation and experiment results have verified that 3DOFAPLOS has a satisfactory result, which improves tracking performance more than 50% compared with the traditional line-of-sight (LOS). Specifically, the mean average error (MAE) of path following under 3DOFAPLOS can be reduced by about 60%, and the root mean square error (RMSE) can be reduced by about 50% compared with LOS.

Global Path-Following Control of Stochastic Underactuated Ships: A Level Curve Approach

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
K. D. Do
Keyword(s):  
Lyapunov Functions ◽  
Control Design ◽  
Path Following ◽  
Level Curve ◽  
Reference Path ◽  
Surface Ship ◽  
Path Following Control

A level curve approach is introduced to design global path-following controllers for an underactuated surface ship. The approach is based on the observation: if the position of the ship satisfies the equation of the reference path, then the ship will be on the path. Thus, the controllers are designed based on Lyapunov's direct and backstepping methods to force the position of the ship to satisfy the equation of the path and to move along the path tangentially. The approach does not require computation of the position from the ship to the path. Weak and strong nonlinear Lyapunov functions are introduced in the control design to overcome difficulties caused by underactuation and to guarantee boundedness of the sway velocity. Simulations are included to illustrate the effectiveness of the proposed results.

Sign in / Sign up

Export Citation Format

Share Document