Biped Robot System Research Articles

Optimal Walking Gait Generator for Biped Robot Using Modified Jaya Optimization Technique

This paper treats the optimization of the biped walking trajectory that can be used as a reference trajectory for control. The biped robot is modeled as a kinetic chain of 11 links connected by 10 joints. The inverse kinematics of the biped is derived for the specified positions of the hips and feet. The objective is to optimize the biped robot able to stably and naturally walking with preset foot-lift magnitude (or preset hip-shift, or preset step-length). The stability of the biped robot is quantified by the distance between the ZMP and the foot center in the step cycle, which represents the first objective function. Additionally, for the biped robot to follow the preset foot-lift value, the difference between the magnitude of foot-lift value and the foot-lift preset value represents the second objective function. Specifically, we minimize the value of the two objective functions by considering the gait parameters of biped robot as variables. The new Jaya optimization algorithm is innovatively applied to optimize the biped gait parameters as to ensure the biped robot walking robustly and steadily. The efficiency of the proposed Jaya-based identification method is compared with the Genetic Algorithm (GA), the Particle Swarm Optimization (PSO), the Central Force Optimization (CFO) and improved Differential Evolution (DE) [Modified Differential Evolution (MDE)] algorithms. The simulation results tested on the real small-sized biped robot system HUBOT-4 demonstrate that the novel proposed algorithm offers an efficient and stable gait for biped robot with precise foot-lift value.

Force-Sensor-Based Surface Recognition With Surface-Property-Dependent Walking-Speed Adjustment of Humanoid Robot

We report the development of a biped-robot system with real-time surface recognition and walking-speed adjustment to control the robot motion during walking on different types of surfaces. Four types of test surfaces (i.e. rough foam (RF), smooth foam (SF), thin carpet (TC) and smooth table (ST)) are considered in the system verification. For surface-property recognition we use ultra-thin-membrane force sensors, mounted under the robot feet, and a classification circuit, implemented on an Arduino Uno board. The walking-speed adjustment is performed with an external control circuit, which receives the surface-recognition signal from the classification circuit and sends a feedback signal to the robot controller (i.e. RCB-4HV) for adjusting the walking speed accordingly. We applied the nearest-neighbor-classification algorithm with the Euclidean-distance measure and a set of reference data, to distinguish between the four test surfaces based on the robot's real-time walking pattern. The mean absolute value (MAV) feature descriptor is used to generate four different types of reference walking pattern, corresponding to the four different surfaces. In our experiments it is observed, that the ST surface performs best in terms of average surface-recognition latency (SRL) (~3.6 sec) during walking on same surface. On the other hand, the surface transition from TC to SF showed minimum surface-transition latency (STL) (~8.2 sec) with correct speed change from 135 to 160 robot-motor-configuration frames per stride (frames/stride), while the transition from SF to TC surfaces showed maximum STL (~11.6 sec) including speed change from 160 to 135 frames/stride. The obtained results are useful for development of the next generation of surface-recognition and speed-adjustment systems, implemented in humanoid robots to enable balanced and stable walking in environments with multiple changed surface properties.

Design of a human-like biped locomotion system based on a novel mechatronic methodology

In this article, a formal mechatronic design of a biped robot is addressed. It is considered a model-based system engineering methodology since the continuous updating of information, from analysis and evolution of conceptual designs, demands a large volume of data. The definition of a biped robot comes from the need of a system to perform human-like walking as the problem to be solved. A specific robot configuration results from the analysis of conceptual solutions throughout SysML as the language for modeling the synergistic and automatic integration among engineering disciplines. The general design process is developed according to the well-known V-model for mechatronic systems design; however, a three-dimensional focus is proposed in order to address a variety of domains and their interaction along the design process. The detailed study of the solution is evaluated in order to optimize the joint torques and limbs shape from an anthropometric robot to achieve effective human-like motion. Although the mechatronic design is done for the overall biped robot system, this work is particularly focused on mechanical features as the most representative subsystem that incorporates genetic algorithm optimization based on a numerical Newton–Euler model merged with topology optimization tools to define final geometry of limbs with stiffness maximization.

Observer Design for Estimating Support Force Applied by a Human Operator of a Biped Robot

The recognition of a robot operator’s intention/command is important in human-robot collaboration systems. This paper presents a novel approach to estimating the human operator’s force applied to a robotic system. In our previous study, we proposed a human-operated biped robot for transporting objects on rough terrain, steps or stairs. In this paper, we consider a new control system for the proposed robot, which enables the estimation of the support force applied by a human operator. The dynamics of the proposed robot are modeled by assuming that a support force applied by an operator is considered as a disturbance to each joint. The observer was designed to estimate the disturbance based on a high-gain observer; it was proven that the observer could estimate the disturbance with sufficient accuracy. Simulation results show that the observer successfully estimated the support force as a disturbance even though the disturbance property was completely unknown. In this study, the proposed biped robot system with the observer was expected to provide support to human operators for the cooperative transportation of objects up the stairs.

Robust Control of a Walking Robot System and Controller Design

In this paper, the method of multi-body dynamics is employed to construct the equations of motion for the complicated biped robot system and designed a robust controller for stable dynamic biped robot system. Using this approach, the planned control law can be adjusted continuously in response to the current movement of the feet of the robot, and this adjustment can be accomplished in a very smooth way. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and can provide a powerful safeguard for the robot system. Simulation results are presented to show the system's efficiency and stability in adapting to an uncertain terrain.

A study of the use of fuzzy control theory to stabilize the gait of biped robots

SUMMARYThis paper designs a biped robot to perform appropriate walking exercises according to the terrain, which then walks stably on a flat environment. The concept of fuzzy logic is combined with the Linear Quadratic Regulator (LQR) controller theory to design the best method to allow the biped robot system to have a balanced and stable gait. Traditional controllers are designed using mathematical models of physical systems, but a fuzzy controller is a physical system that uses an inexact mathematical model, which involves sets and membership functions. Fuzzy controllers use fuzzification, fuzzy control rules, and defuzzification. The method and theory of control: A stable gait for robots is achieved using inverse kinematics, fuzzy concepts, the LQR controller theory, path design, and the characteristics of a dynamic equation. It is then simulated using mathematical tools to prove that the system eliminates swinging by biped robots without fuzzy control knowing beforehand the dynamic model the system is using. Proportional-Integral-Differential control achieves a stable gait design in a flat environment.

A coordinated control strategy for stable walking of biped robot with heterogeneous legs

Purpose – The purpose of this paper is to present a coordinated control strategy for stable walking of biped robot with heterogeneous legs (BRHL), which consists of artificial leg (AL) and intelligent bionic leg (IBL).Design/methodology/approach – The original concentrated control in common biped robot system is replaced by a master‐slave dual‐leg coordinated control. P‐type open/closed‐loop iterative learning control is used to realize the time‐varying gait tracking for IBL to AL.Findings – The new control architecture can simplify gait planning scheme of BRHL system with complicated closed‐chain mechanism and mixed driving mode.Research limitations/implications – Designing and constructing a suitable magneto‐rheological damper can greatly improve the control performance of IBL.Practical implications – Master‐slave coordination strategy is suitable for BRHL stable walking control.Originality/value – The concepts and methods of dual‐leg coordination have not been explicitly proposed in single biped robot ...

소형 2족 보행 로봇의 지능형 동작의 구현

A small biped robot system is designed and implemented. The robot system consists of a mechanical robot body, a control system, a sensor system, and a user interface system. The robot has 12 dofs for two legs, 6 dofs for two arms, 2 dofs for a neck, so it has total 20 dofs to have dexterous motion capability. The implemented robot has the capability of performing intelligent actions such as playing soccer, resisting external forces, and walking on a slope terrain. In this paper, we focus on the robot`s capability of playing soccer. The robot uses a color CCD camera attached on its head as a sensor for playing soccer. To make the robot play soccer with only one camera, an algorithm, which consists of searching, localization, and motion planning, is proposed and experimented. The results show that the robot can play soccer successfully in the given environments.

Sensor system of a small biped entertainment robot

SDR-4X II is the latest prototype model of a small biped entertainment robot. It is the improved model of SDR-4X. In this paper we report on the sensing system of this robot, which is important and essential for a small biped entertainment robot which will be used in the home environment. One technology is the design of the motion sensing system, i.e. the inclination sensor system and the force sensor system which obtains the inclination of the trunk and the foot with force. Another technology is the real-world sensing system. One aspect is the touch sensing system. The robot is used in a normal home environment, so we should strongly consider the safety aspects for human. Another is the vision sensor system. The configuration and the distance image acquisition are explained. Next is the audio sensor system which obtains the sound and the voice information. The hardware system and the direction recognition are explained. These sensing systems are the key to making the biped robot walking and dynamic motion highly stable, and understanding the real-world around the robot.

Three Dimensional Digital Simulation of Legged Robots

This paper describes a new simulation method of multidegree-of-motion-freedom mechanical systems with the time-dependent contact and the Coulomb friction, such as a legged robot interacting with the ground and a satellite-mounted manipulator catching an object. The proposed approach is the extension of the open link manipulator simulation method and the contact simulation method of rigid body mechanics. The proposed simulation model can be said to be mathematically exact, thus this approach enables the essential investigation for control algorithms of the mechanical systems. The method is tested on a biped robot system and some results are shown.

Master-slave-type humanoid robot project

In this paper, we point out the importance of developing a master-slave type humanoid robot. Then, for the first stage, we show a concept of a master-slave biped robot and report on the developed master-slave biped robot system. Furthermore, we show the experimental results of an example of master-slave locomotion. Then, from the experimental result, we try to confirm the realizability of the master-slave-type humanoid robot.