1 Abstract— This paper proposes a feedback path controller for an articulated (LHD) mining vehicle. First, we develop a kinematic model of the vehicle in error coordinates expressed in a moving reference frame, which is partially linked to the vehicle. We give a change of coordinates and input combined with a new variable instead of the time- index that transform the original system into a form that can be viewed as a nonlinear time-invariant system. The nonlinear terms in system can be transformed in linear s- variant one by using mean values theorem. Subsequently, linear control feedback is applied to the full nonlinear system and local general stability of the closed-loop system is achieved by using Linear Matrix Inequality (LMI) approach. Simulation results illustrate the effectiveness of the proposed controller. Index Terms— Mining Vehicle, Nonlinear system, Path Control, Linear control law, LMI, general stability. I. INTRODUCTION N recent years, significant advances have been made in designing automated vehicles for use in the mining process [1]. Their application reduces the need of human operators in hazardous areas and improves the working conditions, productivity and safety of the mineworkers. Recently, experimental results from the automatic guidance of LHD (Load-Haul-Dump) articulated vehicles have been reported [2]. Several control solutions for path tracking of such vehicles have also been reported in the literature. For example, path- tracking controller based on the tangent linearization of a reduced-order kinematic vehicle model has been proposed in [3]. It should be noted that, when the control design procedure is based on the reduced order model, the stability of the internal dynamics depends on the direction of motion of the vehicle. To overcome this problem, an alternative is a control scheme based on the use of an alternate reference point for forward and backward driving located at the front and rear vehicle units, respectively. This idea was applied in [4], and a stabilizing controller For the parking problem of a LHD vehicle has been proposed. Another alternative is path following controllers based on the use of two guide points simultaneously [5, 6]. In [7], using computed torque techniques, a path-tracking controller based on a dynamic model of the vehicle was designed. Although, the kinematic model of the LHD vehicle was proven to be flat, [8], and can be converted into chained form, to apply a feedback control based on the chained form representation of the system, we must overcome the difficulties associated with the problem of finding functions that generate a chained set of coordinates for articulated vehicles with off-axle (kingpin) hitching. This control will be also expressed in the chained form coordinates that usually leads complex expressions for the coordinate transformations, especially for articulated vehicles. Moreover, since the flat output represents the coordinates of a reference point that does not belong to the vehicle and changes its position relative to the vehicle body during the turning maneuvers, simplified control designs are even more desirable from a practical point of view. In this paper, we present a feedback path following controller for an articulated (LHD) vehicle based on LMI design techniques. First, a kinematic model of the vehicle in error coordinates expressed in a moving reference frame partially linked to the vehicle is presented. A primary motivation of introducing such a reference frame is, that it decouples the steering dynamics from the longitudinal dynamics of the vehicle. After preliminary change of coordinates an input combined with a new variable instead of the time-index, we arrive at a system that can be viewed as a nonlinear time- invariant system. The nonlinear terms in system can be transformed in linear s-variant one by using mean values theorem. A linear state feedback is applied to the full nonlinear system and local general stability of the origin for the closed- loop system is achieved. The basic motivation in adopting such an approach is to reduce the computational complexity associated with purely nonlinear control techniques. The paper is organized as follows: In Section 2, the kinematic model of the vehicle is presented using error coordinates expressed in a moving reference frame. In Section 3, the design of the proposed controller and stability analysis are given. Simulation results are presented in Section 4. Section 5 contains some conclusions. II. VEHICLE MODEL The articulated (LHD) vehicle considered in this paper, consists of two units connected by a kingpin hitch as shown in Fig. 1. The vehicle is driven by the rear wheels and steered by changing the orientation of the units relative to each other. The wheels are assumed to roll without lateral sliding. The coordinates of the reference point P, which is placed at the center of the rear vehicle axle with respect to an inertial frame Fxy, are denoted by (x,y). The angles θ 1 and θ 2 are the orientation angles of the front and the rear vehicle units with respect to the frame Fxy. A LMI Approach to Feedback Path Control for an Articulated Mining Vehicle P. Bigras, P. Petrov and Tony Wong, Member, IEEE I