This paper presents the development of a simplified model of the lower limbs of a biped robot, composed, basically, of a waist, two femurs, two tibiae and two feet. This mechanical structure has six degrees of freedom and has the approximate dimensions of a human being. The control system was implemented on the Robot Operating System (ROS). Contrariwise to most ROS controllers, a multi-input, multi-output (MIMO) controller using the computed-torque technique is proposed. The Gazebo simulator is used to validate the model and the control system.