Intelligent robots as artificial living creatures

This article introduces a multi locomotion robot, MLR III, which has multiple locomotion types, i.e., not only brachiating but also walking. Conventionally we have studied dexterous locomotion robots and their controller design. One is a simplified two-link robot, Brachiator II. This is an example of an underactuated system in which a robot mechanism has more degrees of freedom than actuators. The desired motions are encoded as the output of a target dynamical system inspired by the pendulum-link motion of an apes brachiation. The other is a monkey-type robot, Brachiator III. Brachiator III achieves a dexterous motion using redundant degrees of freedom. The motion is generated in an empirical learning process on an intelligent structure, on which the learning algorithm coordinates some primitive motions to generate the desired motion. MLR III is an extended locomotion robot that has multiple types of locomotions: brachiation, bipedal walking, and quadrupedal walking, similar to a monkey or gorilla. This article introduces the mechanism and controller design for brachiating motion.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robitics, Oita, Japan, January 24–26, 2003     

Backward Ladder Climbing Locomotion of Humanoid Robot with Gain Overriding Method on Position Control

We studied ladder climbing locomotion with the humanoid robot, DRC‐HUBO, under the constraints suggested by DARPA. Considering the hardware constraints of the robot platform, we planned for the robot to climb backward with four limbs moving separately. Task‐priority whole‐body inverse kinematics was used to generate and track the motion while maintaining COM inside the support polygon. As ladder climbing is a multicontact motion that generates interaction and internal forces, we resolved these issues using a gain overriding method applied to the position control of the motor controllers. This paper also provides various vision methods and posture modification strategies for the restricted conditions of the challenge. We ultimately verified our work in the DRC trials by getting a full score on the ladder task.     

A study on a brachiation controller for a multi-locomotion robot — realization of smooth,continuous brachiation

In this paper, we present a control method to realize smooth continuous brachiation. The target brachiation is basically divided into two actions: a swing action and a locomotion action. In order to realize the continuous brachiation effectively and smoothly, it is necessary to start the swing action as soon as the robot grasps the front target bar at the end of the locomotion action. The collision, which occurs at the moment the robot grips the target bar, affects the pendulum motion of the robot. The action of bending the elbow joint of the swinging arm is proposed in order to solve this gripping problem. The elbow-bending action enables the robot to decrease the impact forces and use the excess mechanical energy after the end of the locomotion phase. Thus, there is no loss of energy and waste of time during the subsequent swing phase. Experimental results show that the robot can successfully achieve smooth, continuous brachiation.     

具有多种运动方式的小型模块化双手爪机器人MiniBibot

受尺蠖等动物攀爬动作的启发,开发了一款舵机驱动的具有多种运动方式的小型双手爪机器人MiniBibot.采用模块化方法设计和搭建了机器人系统,以攀爬杆件为控制实例介绍了用户程序开发的步骤和方法.然后根据该机器人的构型,提出了5种可实现的运动方式,并分析了各自的特点和应用.最后通过一系列实验,充分展示和验证了所提出的双手爪机器人系统及其运动方式的有效性和可行性.     

Ladder Climbing Method for the Limb Mechanism Robot ASTERISK

A ladder climbing method for the limb mechanism robot ASTERISK is proposed. This robot has six legs. The upper three legs hold on to the upper rung from both sides alternately, just like pinching it. The lower three legs hold on to the lower rung in the same way. Hence, the robot can take hold of the ladder stably. First, the robot releases the left upper and lower legs from the current rungs, and hangs them on the next rungs while supporting itself with the other four legs. Then, the mid two legs and the right two legs are moved to the next rungs in sequence. Finally, the robot lifts up its body using the six legs. Depending on the relative pose of the robot to the ladder, the robot automatically selects the legs that can support vertical and/or horizontal forces applied by the rungs. The robot then distributes its weight to the legs supporting the vertical force based on their force margins. The legs that cannot support forces are controlled to always touch the rungs slightly in order to pinch the rungs with the other legs. The advantages of the proposed gait and control method are verified by analysis of the leg workspace for generating the ladder climb gait, analysis of the range of force direction that the legs can support, analysis of the joint torques required for ladder climbing and an experiment on force distribution. Finally, the range of ladder pitch variation that ASTERISK can climb is clarified.     

Mechanism and control of mechatronic system with higher degrees of freedom

We introduce two types of dexterous locomotion robots and their controller design approaches. One is a simplified two-link robot “Brachiator II”. This is an example of an underactuated system where a robot mechanism has higher degrees of freedom than actuators. The desired motions are encoded as the output of a target dynamical system inspired by the pendulum-link motion of an ape's brachiation. The other is a monkey-type robot “Brachiator III” which achieves a more dexterous motion with 13 degrees of freedom. The desired motion is generated in an empirical learning process by a learning algorithm and an intelligent structure, in which the learning algorithm adjusts the coordination levels of some primitive motions in order to generate the desired motion. This is an example of a redundant mechanism. We discuss the advantages of these two design approaches.     

Design and motion planning of an autonomous climbing robot with claws

This paper presents the design of a novel robot capable of climbing on vertical and rough surfaces, such as stucco walls. Termed CLIBO (claw inspired robot), the robot can remain in position for a long period of time. Such a capability offers important civilian and military advantages such as surveillance, observation, search and rescue and even for entertainment and games. The robot’s kinematics and motion, is a combination between mimicking a technique commonly used in rock climbing using four limbs to climb and a method used by cats to climb on trees with their claws. It uses four legs, each with four-degrees-of-freedom (4-DOF) and specially designed claws attached to each leg that enable it to maneuver itself up the wall and to move in any direction. At the tip of each leg is a gripping device made of 12 fishing hooks and aligned in such a way that each hook can move independently on the wall’s surface. This design has the advantage of not requiring a tail-like structure that would press against the surface to balance its weight. A locomotion algorithm was developed to provide the robot with an autonomous capability for climbing along the pre-designed route. The algorithm takes into account the kinematics of the robot and the contact forces applied on the foot pads. In addition, the design provides the robot with the ability to review its gripping strength in order to achieve and maintain a high degree of reliability in its attachment to the wall. An experimental robot was built to validate the model and its motion algorithm. Experiments demonstrate the high reliability of the special gripping device and the efficiency of the motion planning algorithm.     

Algorithms for finding gaits of locomotive mechanisms: case studies for Gorilla robot brachiation

We consider a model of a 24-degree-of-freedom monkey robot that is supposed to perform a brachiation locomotion, i.e. to swing from one row of a horizontal ladder to the next one using the arms. The robot hand is constructed as a planar hook so that the contact point, about which the robot swings, is a passive hinge. We identify the 10 most relevant degrees of freedom for this underactuated mechanical system and formulate a tractable search procedure consisting on the following steps: (a) to introduce a parametrized family of coordination patterns to be enforced on the dynamics with respect to a path coordinate; (b) to formulate geometric equality constraints that are necessary to achieve a periodic locomotion; (c) to generate trajectories from integrable reduced dynamics associated with the passive hinge; (d) to evaluate the energetic cost of transport. Moreover, we observe that a linear approximation of the reduced dynamics can be used for trajectory generation, which allows us to incorporate computation of an approximate gradient of the cost function into the search algorithm significantly improving the computational efficiency.     

Design and Quasi-Static Locomotion Analysis of the Rolling Disk Biped Hybrid Robot

Motivated by the need for greater speed, efficiency, and adaptability in climbing and walking robots, we have developed a bipedal planar robot that complements its walking and climbing capabilities with rolling. Rolling capabilities are provided by an innovative morphology, without the need for additional resources beyond those required by walking and climbing. Herein, we present the design of this robot, the development of a quasi-static rolling controller, and a comparison of experimentally obtained speed and energy data for walking versus rolling locomotion. We show that rolling can significantly improve energy efficiency over walking—as much as a factor of 5.5. We also demonstrate the ability to roll up slopes and roll over obstacles.      

A novel compound biped locomotion algorithm for humanoid robots to realize biped walking

In this paper, a compound biped locomotion algorithm for a humanoid robot under development is presented. This paper is organized in two main parts. In the first part, it mainly focuses on the structural design for the humanoid. In the second part, the compound biped locomotion algorithm is presented based on the reference motion and reference Zero Moment Point （ZMP）. This novel algorithm includes calculation of the upper body motion and trajectory of the Center of Gravity （COG） of the robot. First, disturbances from the environment are eliminated by the compensational movement of the upper body; then based on the error between a reference ZMP and the real ZMP as well as the relation between ZMP and CoG, the CoG error is calculated, thus leading to the CoG trajectory. Then, the motion of the robot converges to its reference motion, generating stable biped walking. Because the calculation of upper body motion and trajectory of CoG both depend on the reference motion, they can work in parallel, thus providing double insurances against the robot＇s collapse. Finally, the algorithm is validated by different kinds of simulation experiments.     

Sensing and gait planning of quadruped walking and climbing robot for traversing in complex environment

In this paper, a general study on improving adaptability of quadruped walking and climbing robot in complex environment is presented. First, a sensing system composed of range and gyroscope sensors in a novel arrangement is developed. By combining the sensing signals and the internal state of the robot, the surface geometry of the environment is sufficiently reconstructed in real-time. Secondly, a planning algorithm for the robot to overcome the reconstructed environment is conducted. Based on the reshaped surface, the planning algorithm not only provides the exact body trajectory and foot positions but also the adaptability of the robot in a specific environment. A method to improve the adaptability of the walking and climbing robot is also introduced. Thanks to the adherent ability of the robot, the center of gravity of the robot is allowed to move outside the support polygon to increase the reach-ability of the next swing leg. Finally, the effectiveness of the proposed approach is verified by the performances of the experiments in complex environments using a quadruped walking and climbing robot named MRWALLSPECT IV.     

Dynamic modeling and step-climbing analysis of a two-wheeled stair-climbing inverted pendulum robot

ABSTRACT

In this study, the control of a two-wheeled stair-climbing inverted pendulum robot and its climbing motion are analyzed and discussed. The robot adopts a state-feedback controller with a feed-forward constant to stabilize the body and achieve step-climbing motion. The control parameter is considered based on the dynamic model motion on a flat surface and the static model of motion on the step. For climbing stairs with a narrow step tread, a constant torque is applied to reduce the space required for recovering the body stability after climbing. The stability of the robot is numerically analyzed by analyzing the orbital stability of its limit cycle. The stability analysis shows that the control method can achieve a stable stair-climbing motion. The effectiveness of the control method is demonstrated through an experiment. The result indicates that the robot can climb the stairs, and the required time for climbing a single step is approximately 1.8?s.     

仿壁虎机器人足端工作空间分析及其实现协调运动的步态规划

基于对壁虎爬行运动的研究,提出一种四足仿壁虎爬壁机器人.对其机械结构、运动学、足端工作空间和越障能力进行了分析,规划了两种爬行步态,并针对实验中出现的过驱动问题进行了分析,设计了一种多关节协调控制算法.实验结果表明,使用该控制算法的机器人运动是协调稳定的,验证了分析结果的正确性和控制算法的有效性.     

Stability Analysis of a Wheel-Track-Leg Hybrid Mobile Robot

This paper proposes a new wheel-track-leg hybrid robot. The hybrid robot comprises a robot body, four driving mechanisms, four independent track devices, two supporting legs and one wheel lifting mechanism, which can fully benefit different advantages from wheeled, tracked and legged robots to adapt itself to varied landforms (the rough terrain and high obstacle). Based on the symmetrical mechanical structure, locomotion modes of the mobile robot are analyzed. With the coordinate transformation matrix, the center of mass of the robot is described. Moreover, the stability pyramid method is used to analyze on the climbing motion, especially in the hybrid locomotion mode. Through theoretical analysis, simulation and experimental verification, it’s proven that the robot can remain stable in the process of climbing motion.     

灵长类仿生机器人悬臂运动仿生控制综述

灵长类仿生机器人是通过智能机械手段模仿灵长类运动的一类机器人,针对其悬臂运动仿生的控制研究是该领域的热点.综述了目前灵长类仿生机器人悬臂运动仿生控制的研究方法,给出了悬臂运动仿生控制的一般方法与基于"动态伺服"理论的悬臂运动仿生控制策略,提出了悬臂运动仿生控制中亟待解决的若干问题,并对今后灵长类仿生机器人悬臂运动仿生控...     

Generation of bipedal walking through interactions among the robot dynamics,the oscillator dynamics,and the environment: Stability characteristics of a five-link planar biped robot

We previously developed a locomotion control system for a biped robot using nonlinear oscillators and verified the performance of this system in order to establish adaptive walking through the interactions among the robot dynamics, the oscillator dynamics, and the environment. In order to clarify these mechanisms, we investigate the stability characteristics of walking using a five-link planar biped robot with a torso and knee joints that has an internal oscillator with a stable limit cycle to generate the joint motions. Herein we conduct numerical simulations and a stability analysis, where we analytically obtain approximate periodic solutions and examine local stability using a Poincaré map. These analyses reveal (1) stability characteristics due to locomotion speed, torso, and knee motion, (2) stability improvement due to the modulation of oscillator states based on phase resetting using foot-contact information, and (3) the optimal parameter in the oscillator dynamics for adequately exploiting the interactions among the robot dynamics, the oscillator dynamics, and the environment in order to increase walking stability. The results of the present study demonstrate the advantage and usefulness of locomotion control using oscillators through mutual interactions.     

A control for an insectomorphic robot in climbing to the top of a vertical corner and in moving on a step ladder

For a six-legged robot, the problem of climbing a roof of a vertical right dihedral corner along its walls and a vertical high shelf with the help of a step ladder is investigated. The motions are realized with the help of the dry friction forces. The motion of the robot is formed by imposing servo-constraints in the form of adaptive step cycles of legs and the required geometric structure of body motion. An asymptotically stable program motion of legs relative to the body and the whole system is implemented by a PD controller. The results of 3D computer simulation of the controlled robot dynamics are presented.     

一种新型爬壁机器人机构及运动学研究

提出了一种新型爬壁机器人机构,介绍了机构的构型及结构特点,推导了运动学正、逆解方程式,规划了直线行走、平面旋转及交叉面跨越三种运动模式．机构构型及运动模式的分析表明,该机构具有体积小、运动特性较好的特点．仿真结果证明,该机器人在运动过程中所需吸附力矩较小且占据的空间较少．     

An approach to analyzing biped locomotion dynamics and designing robot locomotion controls

An approach to analyzing biped locomotion problems is presented. This approach applies the principles of Lagrangian dynamics to derive the equations of motion of locomotion gaits, state-variable techniques to analyze locomotion dynamics, and multivariable feedback to design locomotion controls. A robot model which has no knee joints or feet and is constrained to motion in the sagittal plane is chosen as a sufficiently simple model of a biped to illustrate the approach. A goal of the analysis is the design of a locomotion control for the robot which produces a walking gait having a velocity and stride length similar to those of a human walking gait. The principle feature of the approach is a much deeper understanding of the dynamics of biped locomotion than previous approaches have provided.     

Adaptive behavior in turning of an oscillator-driven biped robot

This paper concentrates on a biped robot’s turning behavior that consists of straight and curved walking and the transition between these two patterns. We investigate how a robot achieves adaptive walking during such turning by focusing on rhythm control and propose a locomotion control system that generates robot motions by rhythmic signals from internal oscillators and modulates signal generation based on touch sensor signals. First, we verify that the robot attains limit cycles of straight and curved walking by numerical simulations and hardware experiments. Second, we examine the transition between these walking patterns based on the basin of attraction of the limit cycles in numerical simulations. Finally, we verify whether the robot actually accomplishes transition and turning by hardware experiments. This paper clarifies that the robot establishes such turning motions by adequate modulation of walking rhythm and phase through interactions between the dynamics of its mechanical system, oscillators, and environment.