Chieh Chen

Steering and independent braking control for tractor-semitrailer vehicles in automated highway systems

A steering and independent braking control for a tractor-semitrailer vehicle is proposed to achieve lane following in automated highway systems. Independent braking force of the semitrailer is utilized to stabilize the trailer yaw motion and thus to prevent the potential occurrence of jack-knifing. The control algorithm is designed by the input/output linearization and the adaptive backstepping design methodologies.

Lateral control of commercial heavy vehicles

Two nonlinear lateral control algorithms are designed for a tractor-semitrailer type commercial heavy vehicle. The baseline steering control algorithm is designed utilizing input-output linearization. To enhance the lateral stability and furthermore reduce tracking errors of the trailer, braking forces are independently controlled on the inner and outer wheels of the trailer. The coordinated steering and braking control algorithm is designed based on the multivariable backstepping technique. Simulations conducted using the complex model show that the trailer yaw errors under coordinated steering and independent braking force control are much smaller than those without independent braking force control.

Lane changing with look-down reference systems on automated highways

Abstract Automated lane changing is a vital component of the steering control system for automated vehicles. The most important requirements of such maneuvers are smoothness and robustness. Look-down sensing systems face the challenge of having to bridge the gap whenever reference lines of the respective lanes are not measurable. This paper discusses two methods that were successfully employed in the platoon scenario of the 1997 National Automated Highway Systems Consortium Feasibility Demonstration in San Diego, USA: infrastructure-guided lane changes using an additional cross-over marker reference, and free lane changes using a yaw rate sensor for dead reckoning. Both systems achieved good passenger comfort and exhibited high reliability. Similar techniques were applied to the entrance and exit ramps of the automated highways.

Steering and braking control of tractor-semitrailer vehicles in automated highway systems

Linear quadratic optimal control with and without frequency shaping is utilized to design a steering controller for tractor-semitrailer vehicles in automated highway systems (AHS). To enhance driving safety, the authors propose to use independent braking forces in the trailer as another control input. The combined steering and braking controller is designed by utilizing input/output linearization and backstepping design techniques.

Nonlinear damping in vehicle lateral control: theory and experiment

The sensor and actuator limits in real-world control systems imposes unavoidable tradeoffs between performance and the size of the operating region. When linear control design techniques are used, these limits are either neglected or accounted for by lowering the gains of the controller. The former results in severe reduction of the operating region, while the latter yields low performance. These tradeoffs can often be mitigated by using a nonlinear control strategy, in which nonlinear terms are intentionally introduced in order to implement different design objectives in different operating regions. In this paper, nonlinear damping is utilized as a design tool in lateral control of automated vehicles. Design considerations of the vehicle lateral controller include lateral tracking errors, passenger ride quality and reference/sensing system characteristics. It is shown that the intentionally introduced nonlinear damping term in the feedback loop possesses several favorable design features in the lateral control system. Experimental results using a full scale automated vehicle show that passenger comfort can be enhanced for small errors by significantly reducing the original controller gains, while at the same time achieving the same level of maximum lateral tracking errors.

Changing Lanes on Automated Highways with Look-Down Reference Systems 1

Abstract Lane change is a vital component of the steering control system for automated vehicles. Look-down system faces the challenge of having to bridge the gap between the references in the center of the respective lanes. This paper discusses two methods that were employed in the platoon demonstration of the National Automated Highway Systems Consortium: infrastructure guided lane changes using cross-over references and free lane changes using dead-reckoning. Similar techniques were applied to steering control on entrance and exit ramps of automated highways.

Passivity-Based Nonlinear Observer for Lateral Control of Tractor-Trailer Vehicles in Automated Highway Systems 1

In this paper, the authors propose a nonlinear observer to estimate vehicle lateral velocity and yaw rates for lateral motion control of tractor-trailer vehicles in automated highway systems (AHS). The observer design takes into account passivity and damping, features that are inherent in vehicle systems. Simulation results are reported.

Control of a class of multivariable nonlinear systems without vector relative degrees: a backstepping approach

A new control approach for a class of multivariable nonlinear systems whose decoupling matrix is singular is presented. For this class of systems, local decoupling may be achieved by dynamic compensation. Instead of decoupling the nonlinear system by adding chains of integrators in the input channels, we modify the dynamic extension algorithm by incorporating backstepping design methods to partially close the loop in each design step. The resulting control law by this new approach is a static state feedback law. Although the final closed loop form of the nonlinear system is not decoupled, each output is controlled to the desired value asymptotically. A design example is given to illustrate this approach.