Bum-Joo Lee

Modifiable Walking Pattern of a Humanoid Robot by Using Allowable ZMP Variation

In order to handle complex navigational commands, this paper proposes a novel algorithm that can modify a walking period and a step length in both sagittal and lateral planes. By allowing a variation of zero moment point (ZMP) over the convex hull of foot polygon, it is possible to change the center of mass (CM) position and velocity independently throughout the single support phase. This permits a range of dynamic walking motion, which is not achievable using the 3-D linear inverted pendulum mode (3D-LIPM). In addition, the proposed algorithm enables to determine the dynamic feasibility of desired motion via the construction of feasible region, which is explicitly computed from the current CM state with simple ZMP functions. Moreover, adopting the closed-form functions makes it possible to calculate the algorithm in real time. The effectiveness of the proposed algorithm is demonstrated through both computer simulation and experiment on the humanoid robot, HanSaRam-VII, developed at the Robot Intelligence Technology (RIT) laboratory, Korea Advanced Institute of Science and Technology (KAIST).

Paired Structured Light for Structural Health Monitoring Robot System

The displacement measurement in structural health monitoring (SHM), though important, was not popular due to inaccessibility of the civil infrastructures and high installation cost. The currently popular approaches use accelerometer, strain gauge, PZT, GPS, etc., most of which indirectly measure the displacement and require high cost to install and maintain. Thus the development of SHM system that directly measures the displacement of the structure using low-cost sensors is urgently needed. In this article, a multiple paired structured light (SL) system is proposed as a displacement measurement system for a massive structure. The proposed paired SL module which consists of cheap cameras and lasers is inexpensive to implement and can directly measure the accurate relative displacement between any two locations on the structure. Based on various simulations, a minimal configuration of the paired SL module is found. And Newton—Raphson and extended Kalman filter-based displacement estimation methods are proposed by deriving a kinematic equation and its constraints. By building a prototype of the paired SL module, some real experiments are performed to show the feasibility of the system for long-span structural displacement measurement.

Command State-Based Modifiable Walking Pattern Generation on an Inclined Plane in Pitch and Roll Directions for Humanoid Robots

Previous research related to walking on an inclined plane for humanoid robots, including the 3-D linear inverted pendulum model (3D-LIPM) approach, were unable to modify walking period, step length, and walking direction independently without any additional step for adjusting the center of mass (CoM) motion. Moreover, the inclination along the pitch direction was only considered for walking. To solve these problems, a novel command state (CS)-based modifiable walking pattern generator for humanoid robots is proposed for modifiable walking on an inclined plane in both pitch and roll directions. The dynamic equation of the 3D-LIPM on the inclined plane in both pitch and roll directions is derived to obtain the CoM motion. Using the CoM motion, a method for modifiable walking pattern generation on the inclined plane is developed to follow a given CS composed of walking periods, step lengths, and walking directions for both legs. The effectiveness of the proposed walking pattern generator is demonstrated through both simulation and experiment for the small-sized humanoid robot, HanSaRam-IX (HSR-IX).

Landing Force Control for Humanoid Robot by Time-Domain Passivity Approach

This paper proposes a control method to absorb the landing force or the ground reaction force for a stable dynamic walking of a humanoid robot. Humanoid robot may become unstable during walking due to the impulsive contact force of the sudden landing of its foot. Therefore, a control method to decrease the landing force is required. In this paper, time-domain passivity control approach is applied for this purpose. Ground and the foot of the robot are modeled as two one-port network systems that are connected, and exchange energy with each other. The time-domain passivity controller with admittance causality is implemented, which has the landing force as input and foots position to trim off the force as output. The proposed landing force controller can enhance the stability of the walking robot from simple computation. The small-sized humanoid robot, HanSaRam-VII that has 27 DOFs, is developed to verify the proposed scheme through dynamic walking experiments.

Recent progress and development of the humanoid robot HanSaRam

This paper presents an overview of the recent progress and development of the humanoid robot, HanSaRam series, which have been developed in the Robot Intelligence Technology (RIT) Laboratory, KAIST since 2000. The HanSaRam series have been designed and developed as a small-sized robot for researching walking gate generation, navigation, task planning and HuroCup of FIRA. In particular, the performance of the 7th and 8th versions have been remarkably improved in the aspect of walking pattern generation and task planning. This paper describes the overall design and architecture of recently developed two versions of HanSaRam along with a developed vision simulator tool and the real-time walking gate generation scheme, modifiable walking pattern generator.

Compensation for the landing impact force of a humanoid robot by time domain passivity approach

In this paper, a method to reduce the landing impact force is proposed for a stable dynamic walking of a humanoid robot. To measure the meaningful landing impact force, a novel foot mechanism, which uses FSRs (force sensing resistors), is introduced as well. Humanoid robot might become unstable during the walking due to the impulsive contact force from the sudden landing of its foot. Therefore a new control method to decrease the landing impact force has been required. In this paper, time domain passivity control approach is applied for this purpose. Ground and the foot of the robot are modeled as two one-port network systems which are connected and exchanging energy each other. And, the time domain passivity controller which has the landing impact force as input and foots position to trim off the force as output, is implemented. Unlike previous works, the proposed controller can guarantee the stability of the robot system without any dynamic model information at all. The small sized humanoid robot, HanSaRam-VI which has 25 DOFs, with the proposed foot mechanism is developed to verify the proposed approach through dynamic walking experiments

BALANCE CONTROL OF HUMANOID ROBOT FOR HUROSOT

Abstract This paper presents balance control of humanoid robot for HuroSot using its upper body motion and swinging two arms. The upper body is modeled as an inverted pendulum for an on-line compensation. By using the upper body motion it compensates ZMP (Zero Moment Point) error, obtained by FSR (Force Sensitive Resistor) sensors attached on the sole of the foot. Also by swinging the arms it can cancel the yawing moment such that it can walk properly by keeping its overall balance. Experimental results of balance control of HSR-V, a small sized humanoid robot for HuroSot designed and developed in the RIT laboratory at KAIST, are described to demonstrate the effectiveness and applicability of the proposed method.

Landing Force Controller for a Humanoid Robot: Time-Domain Passivity Approach

For the purpose of a humanoid robots stable walking or running, it is important to absorb landing force or ground reaction force which is generated when the robots foot lands on the ground surface. The force can make the robot unstable, and the problem becomes serious if the robot runs. This paper proposes a control system, which can absorb the landing force of a humanoid robot. Time-domain passivity control approach is applied for this purpose. Ground and the robots foot are modeled as two one-port network systems, which are connected and exchange energy with each other. The time-domain passivity controller has the landing force as input and controls the foots position to reduce the force. The proposed controller can guarantee the stability of the robot system without need of any dynamic model information or control parameters. Using small sized humanoid robot, dynamic walking experiments are performed to verify the proposed scheme, and its efficiency is shown from the comparison with the other scheme.

Structural health monitoring robot using paired structured light

The displacement measurement in structural health monitoring (SHM), though important, was not popular due to inaccessibility and the huge size of the civil infrastructures. The frequently employed approaches use accelerometer, strain gauge, PZT, GPS, LVDT(Linear Variable Differential Transformer) etc., where most of them indirectly measure the displacement, require high cost, and are not so practical to install and maintain. Thus the development of SHM system that directly measures the displacement of the structure using low-cost sensors can be very helpful. In this paper, a multiple paired structured light (SL) system is proposed to be used as a structural displacement measurement. The proposed paired SL module is quite cheap to implement and can directly measure the accurate relative displacement between any two locations. Based on some simulations, a minimal configuration of the paired SL module is proposed. And the steepest descent and extended Kalman filtering-based displacement estimation methods are proposed by deriving a kinematic equation and its constraints. After building a prototype of the paired SL module, some real experiments are performed to test the feasibility of the system for the long-span structural displacement monitoring. The proposed system is expected to act also as a visual inspection and active sensing system if the mobility of the robot is utilized.

Multi-objective quantum-inspired evolutionary algorithm-based optimal control of two-link inverted pendulum

This paper proposes a method to generate an optimal trajectory of nonlinear dynamical system and concurrently optimize multiple performance criteria. As the dimensionality of system increases, it is difficult to find values of cost/reward function of conventional optimal controllers. In order to solve this problem, the proposed method employs iterative linear quadratic regulator and multi-objective quantum-inspired evolutionary algorithm to generate various optimal trajectories that satisfy multiple performance criteria. Fuzzy measure and fuzzy integral are also employed for global evaluation by integrating the partial evaluation of each solution over criteria with respect to users degree of consideration for each criterion. Effectiveness of the proposed method is verified by computer simulation carried out for the problem of stabilizing two-link inverted pendulum model.