Hun Ok Lim

Human-like walking with knee stretched, heel-contact and toe-off motion by a humanoid robot

A humanoid robot, WABIAN-2R, capable of human-like walk with stretched knees and heel-contact and toe-off motions is proposed in this paper. WABIAN-2R has two 1-DOF passive joints in its feet to enable it to bend its toes in steady walking. Further, it has two 6-DOF legs, a 2-DOF pelvis, a 2-DOF trunk, two 7-DOF arms with 3-DOF hands, and a 3-DOF neck. In addition, a new algorithm for generating walking patterns with stretched knees and heel-contact and toe-off motions based on the ZMP criterion is described. In this pattern generation, some parameters of the foot trajectories of a biped robot are optimized by using a genetic algorithm in order to generate a continuous and smooth leg motion. Software simulations and walking experiments are conducted, and the effectiveness of the pattern generation and mechanism of WABIAN-2R, which have the ability to realize more human-like walking styles in a humanoid robot, are confirmed

Online walking pattern generation for biped humanoid robot with trunk

This paper describes an online method generating walking patterns for biped humanoid robots having a trunk. Depending on the walking command, the motion patterns of the lower-limbs are created and connected to the prewalking patterns smoothly in online. For the stability of the biped robots, the trunk and the waist motion is generated by a walking stabilization control that is based on the ZMP trajectory and the motion of the lower-limbs. Experimental tests of versatile biped walking on a plane surface are conducted using an auditory interface, and the validity of the online pattern generation method is verified.

Development of a human-like walking robot having two 7-DOF legs and a 2-DOF waist

Almost all conventional biped humanoid robots have difficulties in realizing various walking motions such as knee stretch walking like a human because of an insufficiency of DOF. Therefore, we have developed a 16-DOF biped humanoid robot without a trunk: 3-DOF in each ankle, 1-DOF in each knee, 3-DOF in each hip and 2-DOF in the waist. Using the biped robot, basic experiments are conducted and the effectiveness of the leg mechanism is confirmed.

Design of a battery-powered multi-purpose bipedal locomotor with parallel mechanism

This paper describes the design of a battery driven bipedal robot, which uses 6-DOF parallel mechanisms for its each leg. We have designed this considering a bipedal robot as the leg module that is sufficient for practical use as a multi-purpose locomotor of the robot system. This robot is applicable to various fields, such as medical, welfare and entertainment. In the design of the robot, we have reduced the weight to the maximum extent, taking advantage of the features of the parallel mechanism where the mechanism rigidity is high. Using the developed bipedal locomotor, dynamic walking with the step time of 0.96 sec/step and the step length of 0.2 m/step was conducted, and the effectiveness of its mechanism was confirmed.

A novel method of biped walking pattern generation with predetermined knee joint motion

This paper describes a method of motion pattern generation for biped humanoid robot to walk like humans or walk with various kind of motions. To realize biped walking avoiding singularity at stretching leg, pattern generation uses predetermined knee joint trajectories. Reduction of DOF by predetermination is complemented by waist motion. The effectiveness of generated dynamic walking patterns is confirmed by using a 16-DOF biped robot WABIAN-2/LL.

Evaluation of Various Walking Patterns of Biped Humanoid Robot

This paper describes the evaluation of three different walking patterns of a biped humanoid robot. Stretch-walking patterns with straight legs for a biped robot are compared with conventional walking patterns with bent legs in terms of energy consumption. This paper discusses walking pattern generation for various walks. To confirm the walking pattern evaluation, we have developed a biped robot, WABIAN-2/LL, whose leg mechanism differs from the conventional leg mechanism that has 3 DOF (degrees of freedom) in each ankle, 1 DOF in each knee, 3 DOF in each hip, and 2 DOF in the waist. Walking experiments are conducted with WABIAN-2/LL, and the results demonstrate that stretch walking patterns are effective in terms of energy consumption.

Stretch walking pattern generation for a biped humanoid robot

This paper describes the knee stretch walking of the biped robot that has three degrees of freedom (DOF) in the ankle, one DOF in the knee and three DOF in the hip. To create the stable stretch walking pattern, a walking pattern generation method capable of specifying arbitrarily the knee joint angle is introduced. The motion of the waist avoids the singularity of the swing leg that can exist in single support phase. A compensatory motion algorithm to cancel the moments generated by the motion of the lower-limbs calculates the waist motion. Through stretch walking simulations, the effectiveness of the pattern generation method is confirmed.

Position-based impedance control of a biped humanoid robot

This paper describes position-based impedance control for biped humanoid robot locomotion. The impedance parameters of the biped leg are adjusted in real-time according to the gait phase. In order to reduce the impact/contact forces generated between the contacting foot and the ground, the damping coefficient of the impedance of the landing foot is increased largely during the first half double support phase. In the last half double support phase, the walking pattern of the leg changed by the impedance control is returned to the desired walking pattern by using a polynomial. Also, the large stiffness of the landing leg is given to increase the momentum reduced by the viscosity of the landing leg in the first half single support phase. For the stability of the biped humanoid robot, a balance control that compensates for moments generated by the biped locomotion is employed during a whole walking cycle. For the confirmation of the impedance and balance control, we have developed a life-sized humanoid robot, WABIAN-RIII, which has 43 mechanical d.o.f. Through dynamic walking experiments, the validity of the proposed controls is verified.

Development of a humanoid robot having 2-DOF waist and 2-DOF trunk

A new humanoid robot capable of various motion is proposed in this paper, which has a 2 DOF waist and 2 DOF trunk. A new upper body mechanism is mounted on a leg machine, WABIAN2/LL, and a full scale humanoid robot, WABIAN-2, is constructed in this study. Its trunk is designed to bend forwards, backwards and sideways and rotate in combination with a 2-DOF waist. Also, the upper body is designed in way that makes it able to use a walk-assist machine. Basic walking experiments with and without a walk-assist machine are conducted, and the effectiveness of the mechanism of WABIAN-2 is confirmed

Compensatory motion control for a biped walking robot

This paper addresses a compensatory motion control algorithm of a biped robot to deal with stable dynamic walking on even or uneven terrain. This control algorithm consists of three main parts; the introduction of a virtual plane to consider ZMP (Zero Moment Point); an iteration algorithm to compute the trunk motion; and a program control to realize dynamic walking. The virtual plane is defined as a plane formed by the support points between the surface of terrain and the soles. In order to obtain the trunk motion capable of compensating for the moments produced by the motion of the lower-limbs during the walking, ZMP equation on the virtual plane is computed by using an iteration method. Also, a walking pattern is presented which is composed of the trajectories of lower-limbs, waist and trunk. The walking pattern is commanded to the joints of WL-12RIII (Waseda Leg-Twelve Refined Three) using a program control method. Through walking simulations and experiments on an uneven terrain, such as stairs and sloped terrain, the effectiveness of the control method is verified.