Non Linear Control System for Humanoid Robot to Perform Body Language Movements

Abstract

In social robotics, especially with regard to direct interactions between robots and humans, the robotic movements of the body, arms and head must make an adequate displacement to guarantee an adequate interaction, both from a functional and social point of view. To achieve this, the use of closed-loop control techniques that consider the complex nonlinear dynamics and disturbances inherent in these systems is required. In this paper, an implementation of a nonlinear controller for the tracking of trajectories and a profile of speeds that execute the movements of the arms and head of a humanoid robot based on the mathematical model is proposed. First, the design and implementation of the arms and head are initially presented, then the mathematical model via kinematic and dynamic analysis was performed. With the above, the design of nonlinear controllers such as nonlinear proportional derivative control with gravity compensation, Backstepping control, Sliding Mode control and the application of each of them to the robotic system are presented. A comparative analysis based on a frequency analysis, the efficiency in polynomial trajectories and the implementation requirements allowed selecting the non-linear Backstepping control technique to be implemented. Then, for the implementation, a centralized control architecture is considered, which uses a central microcontroller in the external loop and an internal microcontroller (as internal loop) for each of the actuators. With the above, the selected controller was validated through experiments performed in real time on the implemented humanoid robot, demonstrating proper path tracking of established trajectories for performing body language movements.

Qhali: A Humanoid Robot for Assisting in Mental Health Treatment

“…The articulation controllers also feature a two-level architecture; at the lower level, the control strategy used is based on the information provided by an encoder detailing the position and speed of each motor, along with internal torque regulation via a PI controller, which receives setpoint signals from a non-linear controller based on the backstepping strategy for trajectory tracking; this strategy also uses a velocity profile for arm and head movements [ 35 , 40 ].…”

“…For this reason, it has two arms and an articulated head with two (02) screens to recreate facial expressions. A non-linear control scheme for trajectory tracking and a speed profile that executes the arm and head movements of the Qhali robot with natural motion was presented in [ 35 ]. Figure 10 shows the movements that the robot can perform with the arm and head joints it is equipped with.…”

“…The robot is equipped with a navigation system for autonomous movement and audio-video systems to verbally and non-verbally communicate, express emotions, gestures, and body language, and enhance overall interaction. First, the 3D modeling and mechatronic design processes are developed, along with an approach to the non-linear control strategy to be implemented for the degrees of freedom (DOF) in the robotic arms [ 35 ]. Then, the psychological intervention proposal and its corresponding conceptual and technical requirements are defined.…”