Damoon Soudbakhsh

An emergency evasive maneuver algorithm for vehicles

In this paper a collision avoidance algorithm based on the drivers input is presented. In a near collision situation many drivers try to avoid the obstacle by steering; however, there are many instances that they cannot perform a successful avoidance maneuver, since some may steer too much and go off the road, and others may not steer enough and collide with the obstacle. In this research, an algorithm for activating a collision avoidance system based on the drivers input is presented and tested on human subjects in a car driving simulator.

Enhanced Active Steering System for Collision Avoidance Maneuvers

Design of an advanced controller for active steering systems in evasive maneuvers of vehicles is investigated. Dynamics of the vehicle is modeled with an extended bicycle model using a nonlinear tire model. The developed model is validated with simulation results from commercial vehicle dynamics simulation software. Two control methods were implemented and studied with the desired trajectory path as an input. Both controllers gave very good results comparing to the ones achieved from PID controller. Deviations of the LQR were in the range of only 1 mm, even for the tough maneuvers. The pole placement controller resulted in deviations in the range of micrometers. Both controllers handled disturbances very well.

Comparison of linear and non-linear controllers for active steering of vehicles in evasive manoeuvres

This paper presents different control approaches to perform an evasive collision avoidance manoeuvre using active steering. Linear and non-linear controllers to control the combined lateral and longitudinal motion of the vehicle using predefined trajectories are compared. A proportional–derivative controller, a linear quadratic regulator (LQR), and two different sliding-mode controllers (SMC) were developed. The second SMC model includes an additional velocity error term, which augments the model with a steering actuator term. The controllers were implemented on a bicycle model and a 17 degrees-of-freedom (DOF) vehicle model. The results showed that all controllers perform similarly in controlling the trajectory of the bicycle model. However, in implementation on the non-linear full vehicle dynamics model, the LQR and SMCs provided similar position tracking, but the two SMCs performed better in minimizing the yaw (directional) error at the end of the trajectory. However, at a higher velocity, SMC2 resulted in a more stable manoeuvre than SMC1.

Vehicle steering maneuvers with direct trajectory optimization

Steering control systems have been used to develop vehicle automated lane change maneuvers or evasive maneuvers for collision avoidance. Most of these systems have used predetermined desired trajectories to perform the required maneuvers. In this study, an optimal trajectory is found while ensuring minimization of lateral acceleration throughout the maneuver. Collocation technique was used to numerically solve the nonlinear programming problem. The results show a near optimal trajectory can be achieved. The generated trajectory is compared to that of a fifth-order polynomial. The resultant trajectory was substantially better than the polynomial one, with both a lower peak and the overall lateral accelerations.

Effectiveness and Acceptance of Adaptive Intelligent Speed Adaptation Systems

Intelligent speed adaptation (ISA) systems face significant consumer acceptance hurdles that limit the likelihood of widespread adoption, particularly in the United States. However, if these systems are designed as speed management systems rather than speed limiting systems, with adaptability to individual driving behavior, they may be more likely to meet with consumer acceptance. The results of a fixed-based driving simulator experiment that tested the acceptance and effectiveness of a new type of ISA, called an Advanced Vehicular Speed Adaptation System (AVSAS), are reported. The results of the experiment showed that AVSAS resulted in reductions in driver speeds across a range of roadway types. AVSAS is a speed management system that adapts to an individual drivers speed behavior and the current driving situation. AVSAS resulted in an average reduction of 5% of the maximum speeds and 3% of the average speeds of the drivers on four road segments. As expected, AVSAS did not reduce driver speeds as much as the mandatory control ISA system, and the experiment confirmed the results of tests conducted on ISA systems largely in Europe. Conversely, the results revealed that more participants were willing to purchase AVSAS compared with the information or mandatory ISAs. Although these results show the promise of a trade-off between system effectiveness and acceptability that has been missing in mandatory and information ISA research, AVSAS suggests that a range of ISA system design requirements could encourage the adoption of ISA systems in the United States.

Vehicle Evasive Maneuver Trajectory Optimization Using Collocation Technique

Vehicle evasive maneuvers or sudden lane changes pose stringent conditions on trajectory control, which require not only a desired path following but also a complete consideration of lateral forces and vehicle dynamic stability. Experienced drivers steer the vehicle on a desired path, as much as possible, without creating large lateral forces beyond the stability limits. Steering control systems have been developed to perform similar lane change or evasive maneuvers automatically but with limitations. A control method is developed to find desired trajectory automatically based on the defined design criteria using constrained optimization via collocation technique. The results are compared with two known suitable trajectories. The results show that the proposed control method produces peak lateral acceleration that are lower than the 5th order polynomial trajectory, and overall lateral accelerations that are lower than a comparable trapezoidal acceleration profile.© 2010 ASME

Investigation of Control Design of Vehicle Active Steering

The design of a controller for active steering systems in evasive maneuvers of vehicles is investigated. Dynamics of a vehicle using the bicycle model along with a steering model is developed in state space representation. Parameters of a sports utility vehicle are used. The developed model is validated with simulation results from a commercial vehicle dynamics simulation software. The effects of a PID controller to control the host vehicle in obstacle avoidance maneuvers are investigated. The desired trajectory path is used as an input, and influence of the different gain parameters are studied. Controller can handle disturbances (such as driver’s input) supporting or opposing the maneuver up to a limit. It handles reduced headway distances up to about 60% of the distance to obstacles, but is only capable of keeping the system stable in a small range of velocities.Copyright

A Neighboring Optimal Controller for Disturbance Rejection During Vehicle Evasive Maneuvers

This paper presents design of a neighboring optimal controller for vehicle evasive maneuvers. The developed controller is tested in presence of varying and constant side force disturbances. A model of wind side force is presented and the controller is tested. On simulated vehicle maneuver cases, the controller shows good disturbance rejection capabilities. The controller is able to perform the maneuver even in presence of 30 m/s (67 mph) wind gust with less than 1cm of error. Also, testing the controller with different bank angles shows that even with 10% bank angle the vehicle performs the maneuver with only 5 cm of error.Copyright

NCAP Star Rating and Safety of Rear Seat Occupant

New Car Assessment Program (NCAP) gives star ratings to the vehicles based on their crashworthiness. The program uses results of crash tests performed with 50% male HYBRID III dummies in the driver and right front passenger seats and gives separate star ratings for the driver and right front passenger positions. These star ratings are available from the safer car website [1], and are perceived as an indicator of general safety of the vehicles for people trying to purchase a vehicle. A one-star rating would show the lowest, and five-star would be the highest safety ranking. As the NCAP star ratings of the vehicles have improved over years, front occupant protection has improved as well; however, recent studies have shown that rear occupants are less protected in newer model years of vehicles [2]. Safety of rear occupants is not evaluated with the NCAP program. In this paper an attempt is made to verify whether the NCAP scores can show the level of protection provided to the rear occupants or not.Copyright

Evaluating Different Criteria to Diagnose ACL Rupture Using a Knee Arthrometer

Every year many people suffer from knee injuries. Previous studies on patients with knee injuries has shown that about 40% percent of knee injuries are ligament injuries, and about 50% of the ligament injuries are the Anterior Cruciate Ligament (ACL) injuries [1–2]. Knee arthrometers are widely used to diagnose ACL injuries, along with other methods [3–4]. In the current research, a knee arthrometer which was developed to provide an accurate measurement of AP displacement of the knee [5] was used to measure anterior laxity of the knees of 20 subjects, and the results were analyzed to find better criteria to diagnose ACL rupture using knee arthrometers.© 2009 ASME