Nguyen Thanh Phuong

An optimal control method for biped robot with stable walking gait

This paper proposes an optimal control method for a 10 degree of freedom (DOF) biped robot with stable walking gait. The biped robot is modeled as a 3D inverted pendulum. From dynamic model of the 3D inverted pendulum and under the assumption that center of mass (COM) of the biped robot moves on a horizontal constraint plane, zero moment point (ZMP) equations of the biped robot depending on the coordinate of the center of the pelvis link obtained from the dynamic model of the biped robot are given based on the DdasiaAlembertpsilas principle. A walking pattern is generated based on ZMP tracking control systems that are constructed to track the ZMP of the biped robot to zigzag ZMP reference trajectory decided by the footprint of the biped robot. An optimal tracking controller is designed to control the ZMP tracking control system. From the trajectory of the COM of the biped robot and an arc reference input of the swinging leg, the inverse kinematics solved by the solid geometry method is used to compute the angles of each joint of the biped robot. The simulation and experimental results show the effectiveness of this proposed control method.

Control of two Wheeled Welding Mobile Manipulator

A three-linked manipulator mounted on a two-wheeled mobile platform is used to weld a long curved welding path. A welding torch mounted at the end of a manipulator of the welding mobile manipulator (WMM) must be controlled for tracking a welding path with constant velocity and constant welding angle of torch. In this paper, a decentralized control method is applied to control the WMM considered as two separate subsystems such as a mobile platform and a manipulator. Two decentralized motion controllers are designed to control two subsystems of WMM, respectively. Firstly, based on a tracking error vector of the manipulator and a feedback motion of the mobile platform, a kinematic controller is designed for manipulator. Secondly, based on an another tracking error vector of the mobile platform and a feedback angular velocities of revolution joints of three-link, a sliding mode controller is designed for the mobile platform. These controllers are obtained based on the Lyapunovs function and its stability condition to ensure for the tracking error vectors to be asymptotically stable. Furthermore, simulation and experimental results are presented to illustrate the effectiveness of the proposed algorithm.

Adaptive Control for Welding Mobile Manipulator with Unknown Dimensional Parameters

This paper presents an adaptive tracking control method for a welding mobile manipulator with a kinematic model in which several unknown dimensional parameters exist. The mobile manipulator consists of the manipulator mounts on a mobile-platform. Based on the Lyapunov function, controllers are designed to guarantee stability of the whole system when the end-effector of the manipulator performs a welding task The update laws are also designed to estimate the unknown dimensional parameters. The simulation and experimental results are presented to show the effectiveness of the proposed controllers.

Robust Control of Welding Robot for Tracking a Rectangular Welding Line

This paper highlights a welding robot (WR) for its end effector to track a rectangular welding line (RWL). The WR includes five actuators which use a DC motor as a power source. Two controllers are proposed to control the WRs end effector: a main controller and a servo controller. Firstly, based on WRs kinematic equations and its feedback errors using backstepping method the main controller is proposed to design the reference-inputs for the WRs actuators in order that the WRs end effector tracks the RWL. Secondly, based on the dynamic equation of WRs actuator, the servo controller is designed using an active disturbance rejection control method. Finally, a control system incorporated with the main controller and the servo controllers make the WRs end effector robustly track a RWL in the presence of the modeling uncertainty and disturbances during the welding process. In experiment, the main controller which has a function as a master of the control system links to the five servo controllers which have a function as a slave via I2C communication. The effectiveness of the proposed control system is proven through the simulation and experimental results.

A simple walking control method for biped robot with stable gait

This paper proposes asimple walking control method for a 10 degree of freedom (DOF) biped robot with stable and human-like walking using simple hardware configuration. The biped robot is modeled as a 3D inverted pendulum. A walking pattern is generated based on ZMP tracking control systems, which are constructed to track the ZMP of the biped robot to zigzag ZMP reference trajectory decided by the footprint of the biped robot. An optimal tracking controller is designed to control the ZMP tracking control system. When the ZMP of the biped robot is controlled to track the x and y, ZMP reference trajectories always locates the ZMP of the biped robot inside stable region known as area of the footprint, a trajectory of the COM is generated as a stable walking pattern of the biped robot. Based on the stable walking pattern of the biped robot, a stable walking control method of the biped robot is proposed by using the inverse kinematics.The stable walking control method of the biped robot is implemented by simple hardware using PIC18F4431 and dsPIC30F6014. The simulation and experimental results show the effectiveness of the proposed control method.

A New Approach for Designing Quadruped Robot

Locomotion employed by legged land quadruped is a complex process. It requires the coordination of multiple degrees of freedom. In addition, locomotion control is complex because it requires: adapting to terrain, optimizing the gait, trying to satisfy multiple constraints, therefore, designing of quadruped robot must determine several related factors, which influences the result of the robot. Among of them, the two most important factors are: the mechanical structure and leg configuration; method of locomotion and the control system. This paper proposes a new approach for designing quadruped robot based on the skeleton of dog and the two above factors: simple mechanical structure and leg configuration are designed to simplify the operation of actuator; quadruped robot can be walked and run in a bounding gait with a simple control system.

Modeling and control of synchronous generator: adaptive approach

Designing of the control system for synchronous generator is difficult task. The problem is that the generators usually work under uncertain load. The generator model is unknown. In this situation the adaptive control approach is accepted. In this paper, a new methodology to design an adaptive control system was propose. The controller was build based on RBF network, which approximates the optimal control law found by solving Eulers equation. The parameters of the controller were correcting on-line by an adaptive law. The second Lyapunov method was used to proof the stability of the control system. Simulation results show that the control system has a good quality.