Baek-Kyu Cho

System Design and Dynamic Walking of Humanoid Robot KHR-2

In this paper, we describe the mechanical design, system integration and dynamic walking of the humanoid, KHR-2 (KAIST Humanoid Robot– 2). KHR-2 has 41 DOFs in total, that allows it to imitate various human-like motions. To control all joint axes effectively, the distributed control architecture is used, which reduces computation burden on the main controller, and allows convenient system. A servo motor controller was used as the sub-controller, whereas a 3-axis force/torque sensor and an inertia sensor were used in the sensory system. The main controller attached on the back of KHR-2 communicates with the sub-controllers in real-time through CAN (Controller Area Network) protocol. Windows XP was used as the operation system, whereas RTX HAL extension commercial software was used to realize the real-time control capability in Windows environment. We define the walking pattern and describe several online controllers in each stage. Some of the experimental results of KHR-2 are also presented.

Controllers for running in the humanoid robot, HUBO

This paper discusses the controllers for running in the humanoid robot and verifies the validity of the proposed controllers via experiments. To realize running in a humanoid robot, the overall control structure is composed of an off-line controller and an on-line controller. The main purpose of the online controller is to maintain the dynamic stability while the humanoid robot runs. The on-line controller is composed of the posture balance control in the sagittal plane, the transient balance control in the frontal plane, and the swing ankle pitch compensator in the sagittal plane. These controllers were applied to the humanoid robot, HUBO, and it ran forward stably at a maximum speed of 3.24km/h.

Stabilization of a hopping humanoid robot for a push

This paper discusses the stabilization of a hopping humanoid robot for a push. According to the size of push, two controllers are selected. The posture balance controller is used when the push is small, and the posture balance controller and the foot placement method are activated together when the push is large. To develop the novel controller of the foot placement method, the simplified model is used and linearized Poincare map for single hopping is made. The control law is designed by the pole placement method. The proposed method is verified through the simulation and experiment. In the experiment, HUBO hops well against various pushes.

RUNNING PATTERN GENERATION OF HUMANOID BIPED WITH A FIXED POINT AND ITS REALIZATION

This paper discusses the generation of a running pattern for a humanoid biped and verifies the validity of the proposed method of running pattern generation via experiments. Two running patterns are generated independently in the sagittal plane and in the frontal plane and the two patterns are then combined. When a running pattern is created with resolved momentum control in the sagittal plane, the angular momentum of the robot about the Center of Mass (COM) is set to zero, as the angular momentum causes the robot to rotate. However, this also induces unnatural motion of the upper body of the robot. To solve this problem, the biped was set as a virtual under-actuated robot with a free joint at its support ankle, and a fixed point for a virtual under-actuated system was determined. Following this, a periodic running pattern in the sagittal plane was formulated using the fixed point. The fixed point is easily determined in a numerical approach. In this way, a running pattern in the frontal plane was also generated. In an experiment, a humanoid biped known as KHR-2 ran forward using the proposed running pattern generation method. Its maximum velocity was 2.88 km/h.

Posture Stabilization Strategy for a Trotting Point-foot Quadruped Robot

This paper proposes a posture stabilization strategy for achieving the stable trot gait of a point-foot quadruped robot. Specifically, a stepping strategy (foot placement strategy) has been developed to achieve a stable trot gait. Because in the trot gait of a quadruped robot the diagonal legs can be considered to contact and leave the ground at the same time, the trot gait can be considered as a virtual biped gait. Based on the dynamic model of a virtual biped gait, the stepping point (or the foot placement) that achieves the stabilization of the robot is determined. Finally, the effectiveness of the proposed posture stabilization strategy is validated experimentally.

Development of a Humanoid Robot Platform HUBO FX-1

Many researches about humanoid robot are performed for last decade. There exist outstanding results about hardware platforms and software algorithms and some results become commercial products. Humanoid robot engineering is synthetic study which includes mechanism design, sensor system, control algorithm and so on. But humanoid robot engineering has just symbol of technology, practical usage is very low compare with other robot shapes. Main object of this research is to develop humanoid robot which can be used in industrial or social environment. HUBO FX-1 is humanoid robot which is used for transportation system in social or industrial environment. It can carry luggage or a person according to shape of its upper body

Practical experiment of balancing for a hopping humanoid biped against various disturbances

This paper discusses balancing for a hopping humanoid biped against various disturbances. Contrary to other studies, the present work focuses on the practical experiment with a real humanoid biped, HUBO2. Also, hopping is focused on among various types of locomotion since hopping is simple movement but more dynamic rather than walking. Two control strategies are proposed according to the magnitude of the disturbances. The one is the posture balance control for small disturbance, which uses the ankle torque of the stance leg. The other is to use the posture balancing control and the landing position control together for large disturbance. The landing position controller changes the landing position of the swing foot to maintain stability. The closed form solution of the landing position controller is addressed with the simplified model. As this simplification, both controllers are used together since the landing position controller cannot maintain a perfect balance alone. To this end, practical experiments with HUBO2 are conducted. In the experiments, HUBO2 maintains a balance against not only small disturbance but also large disturbance such as pushing through the proposed control strategies.

Design of a Knee Exoskeleton Using Foot Pressure and Knee Torque Sensors

This study presents the development of a modular knee exoskeleton system that supports the knee joints of hemiplegic patients. The device is designed to realize the polycentric motion of real human knees using a four-bar linkage and to minimize its total weight. In order to determine the users intention, force-sensitive resistors (FSRs) in the users insole, a torque sensor on the robot knee joint, and an encoder in the motor are used. The control algorithm is based on a finite state machine (FSM), where the force control, position control and virtual damping control are applied in each state. The proposed hardware design and algorithm are verified by performing experiments on the standing walking and sitting motion controls while wearing the knee exoskeleton.

RUNNING PATTERN GENERATION WITH A FIXED POINT IN A 2D PLANAR BIPED

This paper discusses the generation of a running pattern for a biped and verifies the validity of the proposed method of running pattern generation via experiments. When a running pattern is created with resolved momentum control, the angular momentum of the robot at the Center of Mass (COM) is set to zero, as the angular momentum causes the robot to rotate. However, this also induces unnatural motion of the upper body of the robot. To resolve this problem, the biped was set to a virtual under-actuated robot with a free joint at its support ankle, and a fixed point for a virtual system was determined. Following this, a new periodic running pattern was formulated using the fixed point. The fixed point is easily determined using a numerical approach. In an experiment, the planar biped ran forward using the proposed pattern generation method for running. Its maximum velocity was 2.88 km/h. In the future, faster running of the biped will be realized in a planar plane and the biped will run in an actual environment.

Running pattern generation of humanoid biped with a fixed point and its realization

This paper discusses the generation of a running pattern for a humanoid biped and verifies the validity of the proposed method of running pattern generation via experiments. When a running pattern is created with resolved momentum control in the sagittal plane, the angular momentum of the robot at the Center of Mass (COM) is set to zero, as the angular momentum causes the robot to rotate. However, this also induces unnatural motion of the upper body of the robot. To solve this problem, the biped was set as a virtual under-actuated robot with a free joint at its support ankle, and a fixed point for a virtual under-actuated system was determined. Following this, a periodic running pattern in the sagittal plane was formulated using the fixed point. The fixed point is easily determined in a numerical approach. In an experiment, a humanoid biped known as KHR-2 ran forward using the proposed running pattern generation method. Its maximum velocity was 2.88 km/h. In the future, faster running and more stable running with controllers will be realized.