Running Robot Research Articles

Joint Mechanism That Mimics Elastic Characteristics in Human Running

Analysis of human running has revealed that the motion of the human leg can be modeled by a compression spring because the joints of the leg behave like a torsion spring in the stance phase. In this paper, we describe the development of a joint mechanism that mimics the elastic characteristics of the joints of the stance leg. The knee was equipped with a mechanism comprising two laminated leaf springs made of carbon fiber-reinforced plastic for adjusting the joint stiffness and a worm gear in order to achieve active movement. Using this mechanism, we were able to achieve joint stiffness mimicking that of a human knee joint that can be adjusted by varying the effective length of one of the laminated leaf springs. The equation proposed for calculating the joint stiffness considers the difference between the position of the fixed point of the leaf spring and the position of the rotational center of the joint. We evaluated the performance of the laminated leaf spring and the effectiveness of the proposed equation for joint stiffness. We were able to make a bipedal robot run with one leg using pelvic oscillation for storing energy produced by the resonance related to leg elasticity.

A Piecewise-Linear Approximation of the Canonical Spring-Loaded Inverted Pendulum Model of Legged Locomotion

Here, we introduce and analyze a novel approximation of the well-established and widely used spring-loaded inverted pendulum (SLIP) model of legged locomotion, which has made several validated predictions of the center-of-mass (CoM) or point-mass motions of animal and robot running. Due to nonlinear stance equations in the existing SLIP model, many linear-based systems theories, analytical tools, and corresponding control strategies cannot be readily applied. In order to provide a significant simplification in the use and analysis of the SLIP model of locomotion, here we develop a novel piecewise-linear, time-invariant approximation. We show that a piecewise-linear system, with the only nonlinearity due to the switching event between stance and flight phases, can predict all the bifurcation features of the established nonlinear SLIP model over the entire three-dimensional model parameter space. Rather than precisely fitting only one particular solution, this approximation is made to quantitatively approximate the entire solution space of the SLIP model and capture all key aspects of solution bifurcation behavior and parametric sensitivity of the original SLIP model. Further, we provide an entirely closed-form solution for the stance trajectory as well as the system states at the end of stance, in terms of common functions that are easy to code and compute. Overall, the closed-form solution is found to be significantly faster than numerical integration when implemented using both matlab and c++. We also provide a closed-form analytical stride map, which is a Poincaré return section from touchdown (TD) to next TD event. This is the simplest closed-form approximate stride mapping yet developed for the SLIP model, enabling ease of analysis and numerical coding, and reducing computational time. The approximate piecewise-linear SLIP model presented here is a significant simplification over previous SLIP-based models and could enable more rapid development of legged locomotion theory, numerical simulations, and controllers.

4脚走行ロボットにおける安定したギャロップ歩容の検討

4脚走行ロボットにおける安定したギャロップ歩容の検討

強化学習に基づく4脚走行ロボットのバウンド歩容獲得

強化学習に基づく4脚走行ロボットのバウンド歩容獲得

A novel method of natural landmark extraction and description for vSLAM

Landmark extraction and matching is a key part of vSLAM. In this paper, a method of landmark extraction and its description based on three-dimensional (3D) information of feature points is proposed. The robot obtains images from its environment via binocular vision, building 3D information of feature points under left camera coordinate system. Then, it uses the method based on improved mean shift algorithm to extract natural landmarks and construct its descriptor, which can be used in fast matching of two landmarks. This method can extract natural landmarks from unstructured environments and tolerate relatively low accuracy of pose estimation. It is suitable for navigation system of a mobile robot running in a complex environment. vSLAM experiments showed its effectiveness.

A novel method of natural landmark extraction and description for vSLAM

Landmark extraction and matching is a key part of vSLAM. In this paper, a method of landmark extraction and its description based on three-dimensional 3D information of feature points is proposed. The robot obtains images from its environment via binocular vision, building 3D information of feature points under left camera coordinate system. Then, it uses the method based on improved mean shift algorithm to extract natural landmarks and construct its descriptor, which can be used in fast matching of two landmarks. This method can extract natural landmarks from unstructured environments and tolerate relatively low accuracy of pose estimation. It is suitable for navigation system of a mobile robot running in a complex environment. vSLAM experiments showed its effectiveness.

Об одной задаче формирования программных законов управления исполнительным уровнем автономных тяжелых МРТК

Heavy vehicles are an important class of the multi-purpose mobile ground vehicles. According to an expert opinion, development of the heavy mobile robots (mobots) based on HTVs will boost the efficiency of different purpose HTVs. It should be underlined that most of the domestic and foreign mobot solutions are usually based on a remote control, when a specially trained expert uses a cable or wireless liaison to control a mobot's spatial motion and other functionalities from a control station. Thus, the individual control method, in which certain functions of a Control station operator can be delegated to the onboard control system, is nowadays of huge interest worldwide. For this reason, within a mobot, besides the remote control modes, the individual control modes can be implemented, which are carried out by the onboard control system only, without any direct involvement of a control station operator. That means formalization of the expert knowledge acquired by human crew members in the form of a set of time diagrams of the operating members' configuration. There are many works dedicated to development of the executive level control actions of small and medium autonomous mobots. However, the achieved results are almost inapplicable for development of the executive level controls for the heavy autonomous mobots. To a great extent this is due to the fact that there are many uncertainties concerning the movement process of the mobots of the aforesaid class. Such uncertainties include imperfect dynamics model of the mobot, complexity of interaction between the robot's running gear and the movement surface, etc. This article is dedicated to the software of the mobot execution level control actions in the standalone mode. Employment of the methods of the situation control and formalization of the expert knowledge made it possible to implement the software for the execution level control actions in the form of a set of coherent time diagrams showing variation of the operating members' configuration in the conditions of uncertainties.

Control Power Reduction and Frequency Bandwidth Enlargement of Robotic Legs by Nonlinear Resonance

Legged robots are regarded as a new means for transportation at uneven terrains and dangerous situations. In particular, quadruped robots that are capable of high-speed running are receiving great attention due to their superior mobility. The legs of such high-speed running robots rapidly repeat the swing and stance motions. Therefore, the legs of high-speed running robots should exhibit low impedance and friction for fast swing motions, while it is required to produce a significantly large actuation force for propulsion of the robot body in a stance phase. For this purpose, a direct-driven actuation mechanism was proposed for the Cheetaroid robot in our previous work. In this paper, in order to further enlarge the frequency bandwidth of the leg module and to reduce the required control (i.e., actuation) power, a dual-stage spring is designed to introduce a motion-adaptive resonance into the system. The structure and parameters of the dual-stage spring are determined in an optimal manner to minimize the control power. The resonance due to the dual-stage spring occurs only during high-speed locomotion, since the overall mechanism is designed such that the spring force is applied to the leg for high-speed locomotion only. The proposed system is verified by simulation studies and experimental results in this paper.

Utilization of Human-Like Pelvic Rotation for Running Robot

The spring loaded inverted pendulum (SLIP) is used to model human running. It is based on a characteristic feature of human running, in which the linear-spring-like motion of the standing leg is produced by the joint stiffness of the knee and ankle. Although this model is widely used in robotics, it does not include human-like pelvic motion. In this study, we show that the pelvis actually contributes to the increase in jumping force and absorption of landing impact. On the basis of this finding, we propose a new model, SLIP2 (spring loaded inverted pendulum with pelvis), to improve running in humanoid robots. The model is composed of a body mass, a pelvis, and leg springs, and, it can control its springs while running by use of pelvic movement in the frontal plane. To achieve running motions, we developed a running control system that includes a pelvic oscillation controller to attain control over jumping power and a landing placement controller to adjust the running speed. We also developed a new running robot by using the SLIP2 model and performed hopping and running experiments to evaluate the model. The developed robot could accomplish hopping motions only by pelvic movement. The results also established that the difference between the pelvic rotational phase and the oscillation phase of the vertical mass displacement affects the jumping force. In addition, the robot demonstrated the ability to run with a foot placement controller depending on the reference running speed.

Integration of mobile manipulators in an industrial production

Purpose – The purpose of this study has been to evaluate the technology of autonomous mobile manipulation in a real world industrial manufacturing environment. The objective has been to obtain experience in the integration with existing equipment and determine key challenges in maturing the technology to a level of readiness suitable for industry. Despite much research within the topic of industrial mobile manipulation, the technology has not yet found its way to the industry. To mature the technology to a level of readiness suitable for industry real-world experience is crucial. This paper reports from such a real-world industrial experiment with two mobile manipulators. Design/methodology/approach – In the experiment, autonomous industrial mobile manipulators are integrated into the actual manufacturing environment of the pump manufacturer Grundfos. The two robots together solve the task of producing rotors; a task constituted by several sub-tasks ranging from logistics to complex assembly. With a total duration of 10 days, the experiment includes workspace adaptation, safety regulations, rapid robot instruction and running production. Findings – With a setup time of less than one day, it was possible to program both robots to perform the production scenario in collaboration. Despite the success, the experiment clearly demonstrated several topics in need of further research before the technology can be made available to the industry: robustness and cycle time, safety investigations and possibly standardization, and robot and workstation re-configurability. Originality/value – Despite the attention of research around the world, the topic of industrial mobile manipulation has only seen a limited number of real-world integrations. This work reports from a comprehensive integration into a real-world running production and thus reports on the key challenges identified from this integration.

Identifying Ground-Robot Impedance to Improve Terrain Adaptability in Running Robots

To date, running robots are still outperformed by animals, but their dynamic behaviour can be described by the same model. This coincidence means that biomechanical studies can reveal much about the adaptability and energy efficiency of walking mechanisms. In particular, animals adjust their leg stiffness to negotiate terrains with different stiffnesses to keep the total leg-ground stiffness constant. In this work, we aim to provide one method to identify ground-robot impedance so that control can be applied to emulate the aforementioned animal behaviour. Experimental results of the method are presented, showing well-differentiated estimations on four different types of terrain. Additionally, an analysis of the convergence time is presented and compared with the contact time of humans while running, indicating that the method is suitable for use at high speeds.

Biped Robot Research at Waseda University

Waseda University has researched on biped robots since 1967. This paper describes our latest biped robots: (i) WABIAN-2, (ii) a biped running robot, and (iii) WL-16. WABIAN-2 is a biped humanoid robot and has realized a human-like walk with the knees stretched by utilizing a 2-DOF waist mimicking a human’s pelvic motion. We are developing a new biped humanoid robot which can jump and run by utilizing a pelvic movement and leg elasticity. WL-16 is a human-carrying biped vehicle.

高速2足走行システムACHIRESの開発

高速2足走行システムACHIRESの開発

2P1-U03 双腕の運動を利用した2足走行の高速化手法

In this paper, we show a novel speeding-up method for biped running using motions of the arms. Many biped running robots do not use motions of the arms. In proposed method, biped robots generate motions of the arms for appropriate high-speed running. We show the effectiveness of the proposed method through numerical simulations.

1P2-B05 ヒューマノイドロボットの高速走行制御に関する研究 : 走行の基礎検証

Recently, a lot of researches for bipedal locomotion have been conducted. The high-speed running, which means that a Froude number is more than 1 so the robot can conduct only it, has not been achieved until now. In this research, we develop a humanoid robot that achieves the high-speed running, named rapid running robot (R3). The development and control of this robot need an accurate model to analyze the robot's locomotion. We then model R^3 after a real robot, which has already achieved the running, in a dynamic simulator V-REP.

Autonomous Tour Guide Robot using Embedded System Control

This paper describes an interactive autonomous tour guide robot designed to guide visitors through Asia Pacific University Engineering Labs. Although tour guide robots with various self-localization abilities such as mapping has been introduced in the past, these technologies performance still remain challenged by indoor navigation obstacles. The current approach consists of implementing a low cost autonomous indoor tour guide robot running on an embedded system which is the Raspberry pi 2. The autonomous navigation is achieved through wall following using ultrasonic sensors and image processing using a simple webcam. The bitwise image processing comparison method introduced is writing in OpenCV and runs on the Raspberry pi. It grabs images and look for the tags to identify each lab. A recognition accuracy of 98% was attained during the navigation testing in the labs. The user interaction was achieved through voice recognition on an android tablet placed on top of the robot. Google speech recognition API's was used for the communication between the robot and the visitors.

Design of a cat-inspired robotic leg for fast running

This paper introduces a novel design for a robotic leg to achieve a fast running mechanism that is inspired by domestic cats. The skeletomuscular system and parallel leg movement of a cat are analyzed and applied to determine the link parameters and the linkage structure of the proposed mechanism. The linkage design of the leg mechanism is explained, and a kinematic analysis based on vector loop equations is performed. The effectiveness of the proposed mechanism is verified experimentally. A single leg clamped to a vertically moving slider exhibits a step frequency of 4.45 Hz while supporting a 0.5 kg body weight. The biped robot runs at an average speed of 0.75 m/s at a step frequency of 2.8 Hz for a trot gait on flat ground. This leg mechanism can facilitate the development of fast running robot systems.

Energy‐optimized bipedal running of a simple humanoid robot

AbstractA method to optimize energy efficiency for bipedal running robots is presented. A running model of a simple bipedal robot consisting of five rigid bodies connected by actuated revolute joints is introduced. The actuators' torques are generated by a trajectory tracking controller to produce periodic running gaits. The controller's reference trajectories are parameterized by Bézier polynomials. A numerical optimization is used to employ reference trajectories with optimal energy efficiency for average velocities in the range of 1.5 to 5.5 m/s. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Velocity Control of a Bounding Quadruped via Energy Control and Vestibular Reflexes

In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties of a sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new controller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capability. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.

Water bouncing robots: a first step toward large-scale water running robots

SUMMARYRobots running on water have attracted the attention of researchers in the last decades as an alternative to conventional aquatic propulsion mechanisms. Up to now, a large scale robot capable of running on water has not been realized. Bouncing on water is a prerequisite for running on water. For this reason, the development of a water bouncing robot represents a necessary first step. The paper presents the model of a 2-degree-of-freedom water bouncing robot inspired by the pogo-stick, a device for jumping off the ground in a standing position. An analytical model of the impact force between “robot's foot” and water is provided for both water-entry and water-exit phases. Such a model has been integrated in a dynamic simulation of whole robot. The model represents a useful and general framework to gain an insight into the parameters that characterize the efficiency of robot.