Omnidirectional Walking Research Articles

Soft computing-based expert systems to predict energy consumption and stability margin in turning gaits of six-legged robots

Turning gaits are the most general and very important ones for omni-directional walking of a six-legged robot. Soft computing-based expert systems have been developed in the present work to predict specific energy consumption and stability margin of turning gait of a six-legged robot. Besides back-propagation neural network, three approaches based on adaptive neuro-fuzzy inference system have been developed and their performances are compared with each other. Genetic algorithm-tuned multiple adaptive neuro-fuzzy inference systems are found to perform better than other approaches. This could be due to a more exhaustive search conducted by the genetic algorithm in place of back-propagation algorithm and the use of two separate adaptive neuro-fuzzy inference systems for two different outputs.

Dynamic Modeling of Energy Efficient Crab Walking of Hexapod Robot

Crab walking is the most general and very important one for omni-directional walking of a hexapod robot. This paper presents a dynamic model for determining energy consumption and energy efficiency of a hexapod robot during its locomotion over flat terrain with a constant crab angle. The model has been derived for statically stable crab-wave gaits by considering a minimization of dissipating energy for optimal foot force distribution. Two approaches, such as minimization of norm of feet forces and minimization of norm of joint torques have been developed. The variations of average power consumption and energy consumption per weight per traveled length with velocity or stroke have been compared for crab walking with tripod and tetrapod gait patterns. Tetrapod gaits are found to be more energy-efficient compared to the tripod gaits.

Effects of turning gait parameters on energy consumption and stability of a six-legged walking robot

Minimization of energy consumption plays a key role in the locomotion of a multi-legged robot used for various purposes. Turning gaits are the most general and important factors for omni-directional walking of a six-legged robot. This paper presents an analysis on energy consumption of a six-legged robot during its turning motion over a flat terrain. An energy consumption model is developed for statically stable wave gaits in order to minimize dissipating energy for optimal feet forces distributions. The effects of gait parameters, namely angular velocity, angular stroke and duty factors are studied on energy consumption, as the six-legged robot walks along a circular path of constant radius with wave gait. The variations of average power consumption and energy consumption per unit weight per unit traveled length with the angular velocity and angular stroke are compared for the turning gaits of a robot with four different duty factors. Computer simulations show that wave gait with a low duty factor is more energy-efficient compared to that with a high duty factor at the highest possible angular velocity. A stability analysis based on normalized energy stability margin is performed for turning motion of the robot with four duty factors for different angular strokes.

Design and Construction of “ArtRo” Omnidirectional Walking Bipedal Robot using Hierarchical Reactive Behaviors Control Architecture

Bipedal robot locomotion has been a complicated and challenging matter over the time. This paper describes our work on building omnidirectional walking bipedal robot, included mechanical and electrical design aspect, and its behavior control as well. We adopted a technique introduced by Sven Behnke that enables omnidirectional walking on bipedal robot through the use hierarchical reactive behaviors control architecture. We called the robot “ArtRo”. Currently, ArtRo has successfully implemented a body consisting of two legs, lower abdomen, and a dummy weight representing the upper body load, with a total of 12 degrees-of-freedom (DOF). The mechanical system is designed optimally to facilitate the manufacturing process and the computation of robot parameters. The electrical system of ArtRo consists of main controller and actuator system. The main controller is an Atmel’s ATmega128-based microcontroller system. The actuator system implements a special method involving Time-Division Multiplexing (TDM) to control all ArtRo’s servo motors. The Sven Behnke’s technique has a low computational complexity. It is proven by its successful implementation on ArtRo’s main controller. Adaptation of the technique has been successfully implemented, ArtRo is capable to do omnidirectional walking, whether it is forward walking, side walking, or turning on the spot behavior.

2P2-C05 全方向移動型歩行訓練機の動作エリア設定方法開発(リハビリテーションロボティクス・メカトロニクス)

2P2-C05 全方向移動型歩行訓練機の動作エリア設定方法開発(リハビリテーションロボティクス・メカトロニクス)

144 前腕荷重による全方向移動型歩行支援機の方向制御

144 前腕荷重による全方向移動型歩行支援機の方向制御

Thermally Actuated Omnidirectional Walking Microrobot

We describe a walking microrobot that is propelled by cilialike thermal bimorph actuator arrays. The robot consists of two actuator array chips, each having an 8 × 8 array of “motion pixels,” which are composed of four orthogonally oriented cilia. Each group of unidirectional cilia is controlled independently for each chip, which provides planar motion with three degrees of freedom (x, y, θ). The robot is approximately 3 cm in length, 1 cm in width, and 0.9 mm in height and has a mass of 0.5 g. By varying the actuation frequency and motion gait strategy, the direction and velocity of the motion can be controlled. In this paper, we present the system architecture, control mechanism, and modeling of the robot, as well as experimental results, during linear and rotary motion. The robot can carry loads up to seven times its own mass, and it can operate at speeds up to 250 μm/s with step sizes from 1 to 4 μm.

A walking pattern generation method of humanoid robot MAHRU-R

This paper proposes an omni-directional walking pattern generation method for a humanoid robot MAHRU-R. To walk stably without falling down, a humanoid robot needs the walking pattern. Our previous walking pattern method generated the walking pattern with linear polynomials of the zero moment point (ZMP). It implemented the simple walking like forward/backward walking, side step walking and turning. However, this method was not sufficient to satisfy the various walking which is combined by forward/backward walking, side step walking and turning. We needed to upgrade the walking pattern generation method to implement an omni-directional walking. We use the linear inverted pendulum model consisted of ZMP and center of mass in order to simplify the computation of walking pattern. The proposed method assumes that the state of the following stride is same to the state of the current stride. Using this assumption of walking pattern, the proposed method generates the stable walking pattern for various walking. And the proposed scheme generates the ZMP trajectory with the quartic polynomials in order to reduce the fluctuation of ZMP trajectory by various walking. To implement the efficient walking pattern, this method proposes three walking modules: periodic step module, transient step module and steady step module. Each step module utilizes weighted least square method with future ZMP position information. The effectiveness of the proposed method is verified by simulations of various walking. And the proposed method is confirmed by the experiment of real humanoid robot MAHRU-R.

Hardware design and gait generation of humanoid soccer robot Stepper-3D

This paper presents the hardware design and gait generation of humanoid soccer robot Stepper-3D. Virtual Slope Walking, inspired by Passive Dynamic Walking, is introduced for gait generation. In Virtual Slope Walking, by actively extending the stance leg and shortening the swing leg, the robot walks on level ground as it walks down a virtual slope. In practical, Virtual Slope Walking is generated by connecting three key frames in the sagittal plane with sinusoids. Aiming for improving the walking stability, the parallel double crank mechanism are adopted in the leg structure. Experimental results show that Stepper-3D achieves a fast forward walking speed of 0.5 m/s and accomplishes omnidirectional walking. Stepper-3D performed fast and stable walking in the RoboCup 2008 Humanoid competitions.

Gait planning and intelligent control for a quadruped robot

We present a method for designing free gaits for a structurally symmetrical quadruped robot capable of performing statically stable, omnidirectional walking on irregular terrain. The robot’s virtual model is constructed and a control algorithm is proposed by applying virtual components at some strategic locations. The deliberative-based controller can generate flexible sequences of leg transferences while maintaining walking speed, and choose optimum foothold for moving leg based on integration data of exteroceptive terrain profile. Simulation results are presented to show the gait’s efficiency and system’s stability in adapting to an uncertain terrain.

1515 全方向移動型歩行訓練機のための経路追従制御の提案(ロボティクス・メカトロニクスVII)

1515 全方向移動型歩行訓練機のための経路追従制御の提案(ロボティクス・メカトロニクスVII)

1C2-4 重心ずれを考慮した全方向移動歩行訓練機のモデリング及び制御(GS2-1:歩行訓練・歩行支援・歩行評価I,一般セッション)

1C2-4 重心ずれを考慮した全方向移動歩行訓練機のモデリング及び制御(GS2-1:歩行訓練・歩行支援・歩行評価I,一般セッション)

1C3-2 免荷機能付き全方向移動型歩行訓練機(GS2-2:歩行訓練・歩行支援・歩行評価II,一般セッション)

1C3-2 免荷機能付き全方向移動型歩行訓練機(GS2-2:歩行訓練・歩行支援・歩行評価II,一般セッション)

1107 ロバスト制御による全方向移動型歩行訓練機の走行制御(ロボティクス・メカトロニクスII)

1107 ロバスト制御による全方向移動型歩行訓練機の走行制御(ロボティクス・メカトロニクスII)

Reactive Neural Control for Phototaxis and Obstacle Avoidance Behavior of Walking Machines

This paper describes reactive neural control used to generate phototaxis and obstacle avoidance behavior of walking machines. It utilizes discrete-time neurodynamics and consists of two main neural modules: neural preprocessing and modular neural control. The neural preprocessing network acts as a sensory fusion unit. It filters sensory noise and shapes sensory data to drive the corresponding reactive behavior. On the other hand, modular neural control based on a central pattern generator is applied for locomotion of walking machines. It coordinates leg movements and can generate omnidirectional walking. As a result, through a sensorimotor loop this reactive neural controller enables the machines to explore a dynamic environment by avoiding obstacles, turn toward a light source, and then stop near to it. Keywords—Recurrent neural networks, Walking robots, Modular neural control, Phototaxis, Obstacle avoidance behavior.

Omnidirectional walking of legged robots with a failed leg

This paper studies omnidirectional walking of a hexapod robot with a locked joint failure by proposing crab gaits and turning gaits. Due to the reduced workspace of a failed leg, fault-tolerant gaits have limitations in their mobility. As for crab gaits, an accessible range of the crab angle is derived for a given configuration of the failed leg. As for turning gaits, the conditions on turning trajectories guaranteeing fault tolerance are derived for spinning gaits and circling gaits. Based on the principles of fault-tolerant gait planning, periodic crab gaits and turning gaits are proposed in which a hexapod robot realizes tripod walking after a locked joint failure, having a reasonable stride length and stability margin. The proposed fault-tolerant gaits are then applied to an obstacle avoidance problem of a hexapod robot with a locked joint failure. The kinematic constraints of fault-tolerant gaits should be considered in planning the robot trajectory.

Sensor-driven neural control for omnidirectional locomotion and versatile reactive behaviors of walking machines

This article describes modular neural control structures for different walking machines utilizing discrete-time neurodynamics. A simple neural oscillator network serves as a central pattern generator producing the basic rhythmic leg movements. Other modules, like the velocity regulating and the phase switching networks, enable the machines to perform omnidirectional walking as well as reactive behaviors, like obstacle avoidance and different types of tropisms. These behaviors are generated in a sensori-motor loop with respect to appropriate sensor inputs, to which a neural preprocessing is applied. The neuromodules presented are small so that their structure–function relationship can be analysed. The complete controller is general in the sense that it can be easily adapted to different types of even-legged walking machines without changing its internal structure and parameters.

1401 胴体可変機構を持つ4足歩行ロボットの全方位歩行(GS-15 歩行)

1401 胴体可変機構を持つ4足歩行ロボットの全方位歩行(GS-15 歩行)

1208 全方向移動型歩行訓練機の走行制御(ロボティクス・メカトロニクスVI)

1208 全方向移動型歩行訓練機の走行制御(ロボティクス・メカトロニクスVI)

1210 全方向移動型歩行訓練機の制御(ロボティクス・メカトロニクスVI)

1210 全方向移動型歩行訓練機の制御(ロボティクス・メカトロニクスVI)