Gait Generation Method Research Articles

Research of Robot Gait Based on Evolution Algorithms

In this paper, a new gait research for humanoid robot is presented. By computing the trajectory of center of mass (CoM) for humanoid robot, trajectory of hip joint and ankle joint are developed based on 3D inverted pendulum model. The actual location of the waist position obtained by multi-link model through the center of mass for humanoid robot is in coordinate of the waist of humanoid robot. Trajectory of hip joint and ankle joint are calculated. This paper presents a gait generation method with curve fitting. Using genetic algorithm, humanoid robot can autonomously search for a good gait trajectory. The experimental results show that gait trajectory for humanoid robot can be generated by applying to genetic algorithm. Our proposed method is verified satisfactorily.

An Approach to Stable Walking over Uneven Terrain Using a Reflex‐Based Adaptive Gait

This paper describes the implementation of an adaptive gait in a six‐legged walking robot that is capable of generating reactive stepping actions with the same underlying control methodology as an insect for stable walking over uneven terrains. The proposed method of gait generation uses feedback data from onboard sensors to generate an adaptive gait in order to surmount obstacles, gaps and perform stable walking. The paper addresses its implementation through simulations in a visual dynamic simulation environment. Finally the paper draws conclusions about the significance and performance of the proposed gait in terms of tracking errors while navigating in difficult terrains.

A Gait Generation Method for the Compass-type Biped Robot based on Discrete Mechanics

AbstractIn this paper, we consider a new approach based on discrete mechanics to a gait generation problem for the compass-type biped robot. First, both continuous-time and discrete-time models of the compass-type biped robot are derived. We next formulate a discrete gait generation problem for the discrete compass-type biped robot as a finite dimensional nonlinear optimal control problem, and solve it by using the sequential quadratic programming. Then, we propose a transformation method of a discrete-time input into continuous one and apply it to gait generation for the continuous compass-type biped robot. Some simulations are also shown in order to verify the effectiveness of our approach.

2A2-Q03 関節を有するリムレスホイールに対する分岐現象の発生法の提案(受動歩行ロボット)

In this paper, sustainable gait for a rimless wheel with joints is generated on a level ground, in which mechanical energy lost by heel strike is restored by kicking a ground. For the rimless wheel two kinds of period-doubling gait generation methods are proposed. First, period-two gait is generated by different energy restoration, in which each hip angle is the same value. Next, period-two gait is caused by different impact posture, that is, different hip angles when energy restoration by kicking the ground is constant. These methods separate effects of different energy restoration and asymmetricity for period-doubling gait. In the case of asymmetricity, it is shown that period-two gait is less efficient than period-one gait analytically.

Fast Walking Pattern Generation for Humanoid Robot Using Waist Joint Moment Compensation

In order to effectively improve humanoid robot’s dynamic walking capability, COM (center of mass) and ankle trajectories are generated by taking advantages of the gait generation method based on ZMP (zero moment point) preview control and introducing the rotation about the front rear edges of the stance foot. Furthermore, gradual decrease in the COM lateral swing amplitude and waist joint yaw moment compensation are used to get faster speed. Finally, the fast and dynamic walking of 3-D virtual humanoid prototype is realized in virtual physical environment by kinetic simulation software. The effectiveness of the proposed method is illustrated by simulation results.

2A2-F07 半円足を利用した衝突姿勢の非対称化による動的歩容生成

The authors have proposed a novel gait generation method based on asymmetrization of impact posture using the model of rimless wheel with telescopic legs. In this paper, we attach semicircular feet to this model, and investigate what effect the foot shape had on the gait efficiency. We can expect that the gait efficiency is improved by the geometric and physical effects of feet, and that the excessive speed-up in our previous model is suppressed by the braking effect. In addition, we mathematically investigate the geometric action of the toe support phase on the impact posture, and examine the effect through numerical simulations.

4족 보행로봇의 걸음새에 대한 Genetic Programming 기법과 Central Pattern Generator 기반 생성기법의 비교 연구

4족 보행로봇의 빠른 걸음새를 자동으로 생성하는 문제에 대해서 GP(Genetic Programming)와 CPG(Central Pattern Generator) 기반의 두 가지 방식을 비교한다. GP(Genetic Programming)를 이용한 관절좌표계 상에서의 걸음새 생성 기법은 발끝의 자취와 수 많은 자세 파라미터를 사용하는 대신에 적은수의 관절 궤적을 생성하므로 효율적이다. CPG는 뇌로부터의 입력을 받아서 진동적인 출력을 생성하는 신경회로로 고등생물의 걸음 원리를 수학적으로 모델링한 것이다. 바이올로이드로 구성된 4족 보행로봇에 대하여 Webots기반의 ODE 시뮬레이션을 통해 접근 기법들에 대한 최적화를 수행하고 결과를 비교 분석한다. 그리고, 구해진 시뮬레이션과 결과를 실제 로봇에 대해서 각 동작을 실행시켜 보면서 CPG와 GP 기반의 걸음새 방식의 실제적인 성능 및 특성을 고찰한다. Two gait generation methods using GP(genetic programming) and CPG(Central Pattern Generator) are compared to develop a fast locomotion for quadruped robot. GP based technique is an effective way to generate few joint trajectories instead of the locus of paw positions and lots of stance parameters. The CPGs are neural circuits that generate oscillatory output from a input coming from the brain. Optimization for two proposed methods are executed and analysed using Webots simulation for the quadruped robot which is built by Bioloid. Furthermore, simulation results for two proposed methods are experimented in real quadruped robot and performances and motion features of GP and CPG based methods are investigated.

Biological inspiration used for robots motion synthesis

This work presents a biologically inspired method of gait generation. Bipedal gait pattern (for hip and knee joints) was taken into account giving the reference trajectories in a learning task. The four coupled oscillators were taught to generate the outputs similar to those in a human gait. After applying the correction functions the obtained generation method was validated using ZMP criterion. The formula suitable for real-time motion generation taking into account the positioning errors was also formulated. The small real robot prototype was tested to be able walk successfully following the elaborated motion pattern.

Robot gait synthesis using the scheme of human motions skills development

This work presents biologically inspired method of gait generation. Referring to the periodic signals generated by biological CPG, the coupled oscillators with correction functions are used to produce leg joint trajectories. The method of oscillators parameters evaluation using genetic algorithm is described. The correction functions are introduced. The gait formula suitable for real-time motion generation taking into account the positioning errors is given. Generated gait can be used as the basis for modifications to produce more complex motions. The problem of suitability of human gait for bipeds with body proportions different than that in human body is discussed.

A Novel Method of Gait Synthesis for Bipedal Fast Locomotion

Common methods of gait generation of bipedal locomotion based on experimental results, can successfully synthesize biped joints' profiles for a simple walking. However, most of these methods lack sufficient physical backgrounds which can cause major problems for bipeds when performing fast locomotion such as running and jumping. In order to develop a more accurate gait generation method, a thorough study of human running and jumping seems to be necessary. Most biomechanics researchers observed that human dynamics, during fast locomotion, can be modeled by a simple spring loaded inverted pendulum system. Considering this observation, a simple approach for bipedal gait generation in fast locomotion is introduced in this paper. This approach applies a nonlinear control method to synchronize the biped link-segmental dynamics with the spring-mass dynamics. This is done such that while the biped center of mass follows the trajectory of the mass-spring model, the whole biped performs the desired running/jumping process. A computer simulation is done on a three-link under-actuated biped model in order to obtain the robot joints' profiles which ensure repeatable hopping. The initial results are found to be satisfactory, and improvements are currently underway to explore and enhance the capabilities of the proposed method.

Ｒｉｍｌｅｓｓ Ｗｈｅｅｌの安定原理に基づくコンパス型２足ロボットの漸近安定歩容生成

We investigated and identified the conditions necessary for asymptotically stable gait generation in compass-like biped robots from the mechanical energy balance point of view. The equilibrium point at impact in a dynamic gait is uniquely determined by two constraint conditions: keeping the restored mechanical energy constant and settling the relative hip-joint angle to the desired value just before impact. The generated bipedal gait with these two constraints then becomes asymptotically stable around the equilibrium point, as shown by a simple recurrence formula of the kinetic energy just before impact. We verified this stable gait generation method using numerical simulation of virtual passive dynamic walking. The result were compared with those for a rimless wheel and an inherent stability principle was derived. Furthermore, we derived a robust control law using a reference mechanical energy trajectory and demonstrated its effectiveness numerically. Finally, we discuss sufficient conditions for the gait stability in more general cases using an index function.

Biped gait generation and control based on a unified property of passive dynamic walking

Principal mechanisms of passive dynamic walking are studied from the mechanical energy point of view, and novel gait generation and control methods based on passive dynamic walking are proposed. First, a unified property of passive dynamic walking is derived, which shows that the walking system's mechanical energy increases proportionally with respect to the position of the system's center of mass. This yields an interesting indeterminate equation that determines the relation between the system's control torques and its center of mass. By solving this indeterminate equation for the control torque, active dynamic walking on a level can then be realized. In addition, the applications to the robust energy referenced control are discussed. The effectiveness and control performances of the proposed methods have been investigated through numerical simulations.

力学的エネルギー回復に基づく動的歩容生成と制御

Dynamic gait generation of legged robots can considered as a problem to generate limit cycles in a phase space from the mathematical point of view. One of the basic necessary conditions of dynamic walking is to restore the mechanical energy that is dissipated by an impact between the swing leg and the floor at the transition instant. Energy-effective dynamic gait generation then yields the problem on how to restore the mechanical energy effectively during the swing phase. This paper first unifies the gait generation methods proposed so far by introducing a variable virtual gravity concept and two solution formulas. Taking up the energy tracking control and virtual passive dynamic walking as two typical methods, the paper analyzes the control performances from the view of points of energy efficiency and robust stability through numerical simulations. The obtained results are evaluated based on some criterion, and the conditions for maximum efficiency are theoretically clarified. Throughout this paper, we aim to clarify mathematical principle of energy-effective dynamic walking.

パラメータ励振に基づく伸縮脚ロボットの動的歩行制御

It is clarified throughout studies of passive dynamic walking mechanisms that the common necessary condition for dynamic gait generation comes from the requirement on mechanical energy restoration. Until now we have treated only rotational joints of the robot, whereas in this paper we considers a novel dynamic gait generation method based on mechanical energy restoration by parametric excitation phenomenon using telescopic leg actuation. We first introduce a simple biped walking model and a control law for telescopic leg motion, and analyze the typical walking pattern with respect to the change of control and physical parameters by numerical simulations. We then numerically analyze the energy efficiency in the presence of an elastic element by introducing criterions, and show that suitable adjustment of mechanical impedance dramatically increases the energy efficiency. Further, some extensions of the mechanism and control applications are investigated.

Fuzzy Controller for Wall-Climbing Microrobots

This paper presents a fuzzy control system that incorporates sensing, control and planning to improve the performance of the wall-climbing microrobots in unstructured environments. After introduction of the robot system, a task reference method is proposed which is based on a fuzzy multisensor data fusion scheme. The method provides a novel mechanism to efficiently integrate task scheduling, action planning and motion control in a unified framework. A robot gait generation method is described which switches the robot locomotion between different motion modes with the help of a finite state machine driven by sensory information. A fuzzy motion controller is designed to improve control performance and reduce power consumption by the suitable selection of fuzzy sets and inference methods, as well as the definition of corresponding membership functions and control rule bases. A fuzzy logic compensator is developed to compensate the gravitational effects according to different robot configurations and task situations. Experimental results prove the validity of the proposed methods.

A Novel Gait Generation for Biped Walking Robots Based on Mechanical Energy Constraint

This paper proposes novel energy-based gait generation and control methods for biped robots based on an analysis of passive dynamic walking. First, we discuss the essence of dynamic walking using a passive walker on a gentle slope from the mechanical energy point of view. Second, we propose a simple and effective gait-generation method, which imitates the energy behavior in every walking cycle considering the zero-moment point condition and other factors of the active walker. The control strategy is formed by taking into account the features of mechanical energy dissipation and restoration. Following the proposed method, the robot can exhibit a natural and reasonable walk on a level ground without any gait planning and design in advance. The effectiveness of the method is examined through numerical simulations and experiments.

受動歩行を規範とした２足ロボットの歩容生成と制御

This paper studies basic mechanisms of passive dynamic walking from the mechanical energy point of view, and proposes novel gait generation and control methods based on the passive dynamic walking. Firstly, we show the uniform property of passive dynamic walking that, the walking system's mechanical energy increases proportionally with respect to the position of the system's center of gravity, which results in an interesting indeterminate equation that determines the relation between the system's control torques and its center of gravity. We then show that active dynamic walking on a level can be realized by solving this equation for the control torques. Furthermore, the applications to robust energy referenced control, as well as the extension for controlling a kneed biped system are discussed. The effectiveness of the proposed methods have been investigated through numerical simulations.

Quadruped Free Gait Generation Based on the Primary/Secondary Gait

A free gait algorithm is proposed utilizing a new method of gait generation called primary/secondary gait. The primary gait is a fixed sequence of leg transfers with modified leg-end kinematic limits according to the obstacle presence, while the secondary gait is a flexible gait which is generated to adjust the leg-end position. The primary gait is generated considering the following four constraints: stability constraint, kinematic constraint, sequential constraint and neighboring constraints. Primary gait parameters are modified by the influence of the obstacle. Normally, the machine tends to move with the primary gait. When the primary gait cannot move the vehicle, the secondary gait is adopted to serve as a complement of the primary gait. With the proposed primary/secondary gait, it is expected to improve the efficiency of free gait generation while maintaining the mobility of the vehicle. Simulation results are given to demonstrate the efficiency of the proposed methodology.

Quadruped free gait generation for straight-line and circular trajectories

A method of free gait generation is proposed utilizing the primary/secondary gait for both straight line and circular body trajectories. The primary gait is a fixed sequence of leg transfers with modified leg-ends kinematic limits according to the presence of obstacles, while the secondary gait is a flexible gait which is generated to adjust the leg-end position. The primary gait is generated considering the following four constraints: stability constraint, kinematic constraint, sequential constraint and neighboring constraints. A generalized reference coordinate (GRC) system is introduced to describe the vehicle motion. Using the GRC system, all constraints and obstacle influences are expressed by only one set of equations despite the difference of motion mode. The efficiency of free gait generation is improved with the proposed method, and the trajectory of the vehicle body can be designed more naturally. Simulation results are given to demonstrate the efficiency of the proposed methodology.

The standing posture transformation gait of a quadruped walking vehicle

For maximizing the mobility of a quadruped walking robot, it is necessary to analyse the versatility and efficiency of the gait-generation method. This paper defines the behaviour of a walking robo...