Controlling an Autonomous Racing Vehicle: Using Feedforward and Feedback to Control Steering and Speed

2009 ◽  
Author(s):  
Krisada Kritayakirana ◽  
J. Christian Gerdes
Keyword(s):  
Autonomous Vehicle ◽  
Vehicle Stability ◽  
Error Feedback ◽  
Tracking Errors ◽  
Vehicle Handling ◽  
Race Car ◽  
Modeling Errors

This paper describes the algorithms used for controlling an autonomous vehicle that operates at the limits of tire adhesion. The controller is designed to imitate a racecar driver by using both feedforward and feedback to command the steering, throttle, and brakes of the vehicle. The feedforward steering is based on the vehicle handling diagram, while the lanekeeping steering feedback is added to ensure vehicle stability and reduces tracking errors caused by disturbances or modeling errors. The feedforward speed is estimated based on the available friction, while the proportional speed feedback is introduced to mimic a race-car driver modulating the speed to trim the vehicle orientation. Two different speed feedback designs based on lookahead error and heading error are compared. The experiments demonstrate the superiority of heading error feedback, which enables the vehicle to operate at its limits while maintaining minimal lateral and heading errors from the desired trajectory.

scholarly journals Improvement of Vehicle Stability Using Reinforcement Learning

2018 ◽  
Author(s):  
Janaína R. Amaral ◽  
Harald Göllinger ◽  
Thiago A. Fiorentin
Keyword(s):  
Reinforcement Learning ◽  
Learning Algorithm ◽  
Rear Wheel ◽  
Vehicle Stability ◽  
Sideslip Angle ◽  
Vehicle Handling ◽  
Race Car ◽  
Torque Vectoring ◽  
Preliminary Study ◽  
The Cost

This paper presents a preliminary study on the use of reinforcement learning to control the torque vectoring of a small rear wheel driven electric race car in order to improve vehicle handling and vehicle stability. The reinforcement learning algorithm used is Neural Fitted Q Iteration and the sampling of experiences is based on simulations of the vehicle behavior using the software CarMaker. The cost function is based on the position of the states on the phase-plane of sideslip angle and sideslip angular velocity. The resulting controller is able to improve the vehicle handling and stability with a significant reduction in vehicle sideslip angle.

Autonomous Vehicle Safe Operating Speeds on the Automated Skyway Express in Jacksonville, Florida

2021 ◽  
pp. 036119812199183
Author(s):  
Andrew E. Loken ◽  
Joshua S. Steelman ◽  
Scott K. Rosenbaugh ◽  
Ronald K. Faller
Keyword(s):  
Autonomous Vehicles ◽  
Autonomous Vehicle ◽  
Physical Characteristics ◽  
Vehicle Stability ◽  
Conservative Method ◽  
Passenger Vehicles ◽  
Structural Capacity ◽  
Impact Angles ◽  
Unconventional Methods ◽  
Safe Operating

Autonomous vehicles (AV) differ significantly from traditional passenger vehicles in both their behavior and physical characteristics. As such, the validity of the guidance provided in the Manual for Assessing Safety Hardware, Second Edition (MASH 2016) is questionable in AV applications. Impact angles, speeds, and vehicle weights specified in MASH 2016 are inextricably linked to the traditional vehicles underlying the estimates. For AV applications, these parameters must be estimated from the ground up, stepping outside the guidance of MASH 2016. In this paper, a conservative method for evaluating existing infrastructure to support AV traffic is proposed. The method integrates traditional structural analyses with unconventional methods of estimating impact conditions. This methodology was developed for the Jacksonville Transportation Authority, who, when faced with unique challenges in maintaining and expanding their Automated Skyway Express, opted to convert the system from monorail to AV traffic. Leading AV developers were surveyed to develop a portfolio of potential candidates for the conversion. Estimated impact conditions were then compared against the capacity of the system’s existing concrete parapets. Ultimately, safe operating speeds for each AV candidate were recommended on the bases of structural capacity and vehicle stability. All but one AV candidate were deemed capable of safely operating at the desired speed of 25 mph without any modifications to the barrier. Although the methodology was developed for a particular case, it is applicable to future implementations of AVs on existing infrastructure, provided the roadway is confined similarly to the Skyway deck.

scholarly journals Optimizing Deep-Neural-Network-Driven Autonomous Race Car Using Image Scaling

2020 ◽  
Vol 77 ◽  
pp. 04002
Author(s):  
Yaqub Mahmoud ◽  
Yuichi Okuyama ◽  
Tomohide Fukuchi ◽  
Tanaka Kosuke ◽  
Iori Ando
Keyword(s):  
Autonomous Vehicles ◽  
Response Rate ◽  
Autonomous Vehicle ◽  
Image Resolution ◽  
Performance Difference ◽  
Testing Strategy ◽  
Neural Models ◽  
Race Car ◽  
Image Scaling ◽  
Scaling Down

In this work we propose scaling down the image resolution of an autonomous vehicle and measuring the performance difference using pre-determined metrics. We formulated a testing strategy and provided suitable testing metrics for RC driven autonomous vehicles. Our goal is to measure and prove that scaling down an image will result in faster response time and higher speeds. Our model shows an increase in response rate of the neural models, improving safety and results in the car having higher speeds.

The Application of the Elman Network on the Vehicle Handling Stability Control

2011 ◽  
Vol 199-200 ◽  
pp. 1457-1461 ◽  
Author(s):  
Si Jia Zhou ◽  
Jiang Qi Long ◽  
Ke Gang Zhao
Keyword(s):  
Driving Force ◽  
Control Method ◽  
Control Strategies ◽  
Stability Control ◽  
Vehicle Stability ◽  
Elman Network ◽  
Vehicle Handling ◽  
Combined Control ◽  
One Step ◽  
Tracking Response

In this paper, an expanded Elman network is applied to forecast the vehicle dynamic characteristic and a one step predictive control is also put into use to reinforce its handling stability. The combined control strategy is established based on the conception of the distribution of the driving force between the front and rear driving axles that can be easily achieved in an EV. Moreover, in this research, the distribution proportion of longitudinal driving force defining as a parameter is introduced and the control method of vehicle stability with the aid of the distribution proportion between axles is investigated．Simu1ations have been carried out and the results indicate that the proposed control strategies achieve smooth control effects and rapid target tracking response. This method can be easily applied to the vehicles that are driven by motors, and is capable of improving the lateral dynamic stability of vehicles in most conditions．

Experimental Study of a Roll-Plane Hydraulically Interconnected Suspension System Under Vehicle Articulation Mode

2013 ◽  
Author(s):  
Guangzhong Xu ◽  
Holger M. Roser ◽  
Nong Zhang
Keyword(s):  
Experimental Study ◽  
Experimental Analysis ◽  
Dynamic Performance ◽  
Vehicle Stability ◽  
Ground Contact ◽  
Test Results ◽  
Vehicle Dynamic ◽  
Road Vehicle ◽  
Vehicle Handling ◽  
Phase Motion

This paper presents a detailed experimental study to quantitatively assess the performance of a roll-plane Hydraulically Interconnected Suspension (HIS) system in articulation (warp) mode. This mode is critical for better off-road vehicle handling, particularly in utility vehicles. Articulation of a four-wheel vehicle describes the in-phase motion of two diagonally opposed wheels, with adjacent wheels moving out of phase. The widely used anti-roll bars, required for increased roll resistance, also stiffen the articulation mode, which may result in one or more wheels losing ground contact on uneven surfaces, compromising vehicle stability and safety. Yet roll-plane HIS systems are capable of decoupling vehicle roll from articulation. A comparative experimental analysis of HIS and conventional anti-roll bars has been conducted to evaluate vehicle dynamic performance at full-car level under articulation excitation. Test results demonstrate that the HIS system has a negligible effect on wheel travel in articulation mode, offering a significant improvement in vehicle handling and safety over conventional anti-roll bars.

scholarly journals Design of Integrated Autonomous Driving Control System that Incorporates Chassis Controllers for Improving Path Tracking Performance and Vehicle Stability

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 144
Author(s):  
Taewon Ahn ◽  
Yongki Lee ◽  
Kihong Park
Keyword(s):  
Control System ◽  
Sliding Mode ◽  
Autonomous Vehicle ◽  
Safety Margin ◽  
Autonomous Driving ◽  
Path Tracking ◽  
Tracking Performance ◽  
Change Scenario ◽  
Vehicle Stability ◽  
Yaw Moment

This paper describes an integrated autonomous driving (AD) control system for an autonomous vehicle with four independent in-wheel motors (IWMs). The system consists of two parts: the AD controller and the chassis controller. These elements are functionally integrated to improve vehicle stability and path tracking performance. The vehicle is assumed to employ an IWM independently at each wheel. The AD controller implements longitudinal/lateral path tracking using proportional-integral(PI) control and adaptive model predictive control. The chassis controller is composed of two lateral control units: the active front steering (AFS) control and the torque vectoring (TV) control. Jointly, they find the yaw moment to maintain vehicle stability using sliding mode control; AFS is prioritized over TV to enhance safety margin and energy saving. Then, the command yaw moment is optimally distributed to each wheel by solving a constrained least-squares problem. Validation was performed using simulation in a double lane change scenario. The simulation results show that the integrated AD control system of this paper significantly improves the path tracking capability and vehicle stability in comparison with other control systems.

scholarly journals A TRAJECTORY-TRACKING CONTROLLER FOR IMPROVING THE SAFETY AND STABILITY OF FOUR-WHEEL STEERING AUTONOMOUS VEHICLES

Transport ◽  
2021 ◽  
Vol 0 (0) ◽  
pp. 1-17
Author(s):  
Runqiao Liu ◽  
Minxiang Wei ◽  
Nan Sang ◽  
Jianwei Wei
Keyword(s):  
Trajectory Tracking ◽  
Autonomous Vehicles ◽  
Lateral Displacement ◽  
Autonomous Vehicle ◽  
Tracking Errors ◽  
Disturbance Rejection Control ◽  
Tracking Controller ◽  
Turning Radius ◽  
Trajectory Tracking Controller ◽  
Yaw Angle

To achieve anti-crosswind, anti-sideslip, and anti-rollover in trajectory-tracking for Four-Wheel Steering (4WS) autonomous vehicles, a trajectory-tracking controller based on a four-channel Active Disturbance Rejection Control (ADRC) was used to track the desired lateral displacement, longitudinal displacement, yaw angle, and roll angle, and minimize the tracking errors between the actual output values and the desired values through static decoupling steering and braking systems. In addition, the anti-crosswind, anti-sideslip, and anti-rollover simulations were implemented with CarSim®. Finally, the simulation results showed that the 4WS autonomous vehicle with the controller still has good anti-crosswind, anti-sideslip, and anti-rollover performance in path tracking, even under a small turning radius or lowadhesion curved roads.

Vehicle Handling Qualities

1969 ◽  
Vol 184 (1) ◽  
pp. 233-248 ◽  
Author(s):  
F. D. Hales
Keyword(s):  
Quantitative Methods ◽  
Vehicle Stability ◽  
Test Technique ◽  
Vehicle Handling ◽  
Handling Qualities ◽  
Response Mapping ◽  
Pad Test ◽  
Motion Condition ◽  
Non Linear ◽  
The Relationship

The paper is concerned in general with quantitative methods of analysis for the general steady-state motion of an automobile and, in particular, for methods that are able to assess the non-linear characteristics of vehicles. In this context it is observed that any quantity used must satisfy three requirements; it must have a physical significance and be capable of prediction and measurement. For this purpose three basic handling concepts are considered, understeer, static margin and slip/steer gradient. Following the analysis of the perturbation motion about steady circular motion, the concepts are rationalized and related to the theoretical vehicle behaviour. In a discussion of this analysis the relationship between the three concepts are investigated and subsidiary vehicle parameters highlighted. The final stage of the quantitative method outlined is dealt with in a section on experimental procedures. Three procedures, response mapping, tethered testing and steering pad tests, are examined, and the required measurements and analysis processes needed to obtain measurements of the handling qualities are derived. Finally a typical set of experimental results from a response mapping experiment is included as an example of processes described. It is concluded that the concepts of understeer, static margin and slip/steer gradient can be successfully applied theoretically to the general non-linear cornering motion of an automobile, and that experimental techniques exist that yield measurements from which quantities defined by the theoretical analysis can be obtained, with the exception that measurement of static margin in the general non-linear motion condition is not satisfactory because of experimental problems. The tethered test technique and the steering pad test are also able to provide measures of the most important associated vehicle stability parameter.

Stable headway prediction of vehicle platoon based on the 5-degree-of-freedom vehicle model

2018 ◽  
Vol 233 (6) ◽  
pp. 1570-1585 ◽  
Author(s):  
Shuming Shi ◽  
Ling Li ◽  
Yu Mu ◽  
Guanghui Chen
Keyword(s):  
Ad Hoc Network ◽  
Ad Hoc ◽  
Rotational Velocity ◽  
Autonomous Vehicle ◽  
Degree Of Freedom ◽  
Vehicle Stability ◽  
Vehicle Model ◽  
Vehicle System ◽  
Vehicle Platoon ◽  
The Stability

Vehicular ad hoc network and cooperative adaptive cruise control system make vehicle platooning with small headway feasible. In the study of the autonomous vehicle platoon system under the vehicular ad hoc network condition, the linear vehicle model is usually used to analyze the minimum space-gap, safety space-gap, and so on. However, the stability of nonlinear vehicle system shows that there are limitations when using the linearized vehicle model to analyze vehicle stability. The linear model cannot reflect the influence of the system nonlinear coupling on the vehicle stability. Therefore, in this paper, we use the validated 5-degree-of-freedom (longitudinal velocity, lateral velocity, yaw rate, front wheel rotational velocity, and rear wheel rotational velocity) nonlinear model to analyze the stable intra-platoon spacing of the autonomous vehicle platoon system under the condition of VANET. In order to study the safety intra-platoon spacing of vehicle platoon running in the complex path, a following controller is designed for vehicle platoon running in the corners. The controller adopts the method of vertical and horizontal decentralized control. The longitudinal control is to realize the expected space-gap of vehicles in vehicle platoon, and the lateral control is to achieve the position and orientation following of the preceding vehicle. Based on the stability verification of the following controller, the following control characteristics of vehicle system are analyzed, and the stable headway required for vehicles in vehicle platoon running in the complex path is predicted by the method of simulation experiment.

Sign in / Sign up

Export Citation Format

Share Document