The relevant and modern open-architecture testbed described in this paper deals with a synergetic NSC 737664 combination of an effective control approach and a state-of-the-art technology for rapid prototyping that combines a hard real-time control implementation with a software (MATLAB/Simulink) widely used for these applications. In this context, the present paper has three aims: (1) to describe the construction of a differential drive WMR, (2) to show the implementation of a real-time hierarchical control strategy in order to carry out a trajectory tracking control task, and (3) to present a methodology for generating the WMR trajectories (based on cubic splines) which are constructed from the desired data points (x1*, y1*),��, (xn*, yn*).

Furthermore, time-varying parametric trajectories such as straight lines and parabolic curves, are also implemented.To this end, the present paper is organized as follows. Section 2 presents the general description of the WMR construction. Section 3 describes the hierarchical controller law for the kinematic model for the trajectory tracking task. Section 4 gives an algorithm for generating smooth curves based on specific points given in the X-Y plane via cubic splines. Section 5 shows the real-time control implementation for the WMR. Finally, some conclusions and prospects for future research are presented in Section 6.2. Construction of the WMR A mobile robot is, in general, composed of two mechanical subsystems: (1) actuators and sensors and (2) mechanical design. The control of these subsystems requires two electronic stages: (1) the power stage and (2) the acquisition and control stage.

The interaction of these stages is shown in the block diagram presented in Figure 1. The electronic power stage (stage 2) allows interaction between the electronic control interface (stage 3) and the two dynamic subsystems (stage 1). This interaction includes the communication system, the power supply, and the conditioning circuits (in order to interconnect the electronic board DS1104). The strategy used in the PC (using MATLAB/Simulink) keeps the whole system under control, taking into consideration the physical restrictions. Likewise, the control stage comprises the control strategies used to integrate the functioning of each subsystem (based on mathematic models of the plant). Figure 1General block diagram of the WMR prototype.

2.1. Stage 1: Subsystems This part describes the WMR dynamic subsystems a and b, which include actuators, sensors, and the mechanical structure. Subsystem a (motors and sensors) allows propulsion of the WMR in a specified workspace and discrete position sensing. The subsystem b describes the mechanical design.2.1.1. Subsystem GSK-3 a:Actuators and Sensors The prototype described in this work uses DC motors as actuators.