HRP-2W: A humanoid platform for research on support behavior in daily life environments

We introduce a concept of a real-world-oriented humanoid robot that can support humans’ activities in daily life. In such environments, robots have to watch humans, understand their behavior, and support their daily life tasks. In particular, these robots must be capable of such real-world behavior as handling tableware and delivering daily commodities by hand. We developed a humanoid robot, HRP-2W, which has an upper body of HRP-2 [K. Kaneko, F. Kanehiro, S. Kajita, H. Hirukawa, T. Kawasaki, M. Hirata, K. Akachi, T. Isozumi, Humanoid Robot HRP-2, in: Proceedings of the 2004 IEEE International Conference on Robotics & Automation, 2004, pp. 1083–1090] and a wheel module instead of legs, as a research platform to fulfill this aim. We also developed basic software configuration in order to integrate our platform with other research groups. Through experiments, we demonstrated the feasibility of the humanoid robot platform and the potential of the software architecture.     

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.     

Available friction of ladder shoes and slip potential for climbing on a straight ladder

Straight ladder accidents are a major safety problem. As a leading cause of injuries involving straight ladders, slips at the ladder base occur when the required friction exceeds the available friction at the ladder shoe and floor interface. The objectives of this experiment were to measure the available friction at the base of a portable straight ladder in contact with a floor and to estimate the slip potential of the ladder. The results of friction measurements indicated that the measured friction coefficient on the oily surfaces differed among the six commercially available ladder shoes evaluated. A statistical model was used to compare the available friction results from the current study with the friction requirements under different climbing conditions from a previous study based on their stochastic distributions to estimate the slip potential at the base of the ladder. The results showed that different climbing conditions used in the previous study could be supported by available friction on dry surfaces. However, when the ladder was put onto oily surfaces, resulting in a significant reduction in the available friction due to contamination, slip potential was significantly increased.     

Available friction of ladder shoes and slip potential for climbing on a straight ladder

Straight ladder accidents are a major safety problem. As a leading cause of injuries involving straight ladders, slips at the ladder base occur when the required friction exceeds the available friction at the ladder shoe and floor interface. The objectives of this experiment were to measure the available friction at the base of a portable straight ladder in contact with a floor and to estimate the slip potential of the ladder. The results of friction measurements indicated that the measured friction coefficient on the oily surfaces differed among the six commercially available ladder shoes evaluated. A statistical model was used to compare the available friction results from the current study with the friction requirements under different climbing conditions from a previous study based on their stochastic distributions to estimate the slip potential at the base of the ladder. The results showed that different climbing conditions used in the previous study could be supported by available friction on dry surfaces. However, when the ladder was put onto oily surfaces, resulting in a significant reduction in the available friction due to contamination, slip potential was significantly increased.     

Effects of foot placement,hand positioning,age and climbing biodynamics on ladder slip outcomes

Ladder falls frequently cause severe injuries; yet the factors that influence ladder slips/falls are not well understood. This study aimed to quantify (1) the effects of restricted foot placement, hand positioning, climbing direction and age on slip outcomes, and (2) differences in climbing styles leading to slips versus styles leading to non-slips. Thirty-two occupational ladder users from three age groups (18–24, 25–44 and 45–64 years) were unexpectedly slipped climbing a vertical ladder, while being assigned to different foot placement conditions (unrestricted vs. restricted toe clearance) and different hand positions (rails vs. rungs). Constraining foot placement increased the climber's likelihood of slipping (p < 0.01), while younger and older participants slipped more than the middle-aged group (p < 0.01). Longer double stance time, dissimilar and more variable foot and body positioning were found in styles leading to a slip. Maintaining sufficient toe clearance and targeting ladder safety training to younger and older workers may reduce ladder falls.

Practitioner Summary: Ladder falls frequently cause severe occupational fall injuries. This study aims to identify safer ladder climbing techniques and individuals at risk of falling. The results suggest that ladders with unrestricted toe clearance and ladder climbing training programmes, particularly for younger and older workers, may reduce ladder slipping risk.     

Gait design for an ice skating humanoid robot

Basic walking gaits are a common building block for many activities in humanoid robotics, such as robotic soccer. The nature of the walking surface itself also has a strong affect on an appropriate gait. Much work is currently underway in improving humanoid walking gaits by dealing with sloping, debris-filled, or otherwise unstable surfaces. Travel on slippery surfaces such as ice, for example, greatly increases the potential speed of a human, but reduces stability. Humans can compensate for this lack of stability through the adaptation of footwear such as skates, and the development of gaits that allow fast but controlled travel on such footwear.This paper describes the development of a gait to allow a small humanoid robot to propel itself on ice skates across a smooth surface, and includes work with both ice skates and inline skates. The new gait described in this paper relies entirely on motion in the frontal plane to propel the robot, and allows the robot to traverse indoor and outdoor ice surfaces more stably than a classic inverted pendulum-based walking gait when using the same skates. This work is demonstrated using Jennifer, a modified Robotis DARwIn-OP humanoid robot with 20 degrees of freedom.     

Communication capability of telepresence system with the miniature humanoid MH-2

Recently, several different types of telepresence robots have been developed. Their ability to communicate with a person in a remote location has been analyzed to achieve rich communication, including the presence of an operator. These studies focused on human-sized robots, small-sized non-humanoid robots, or small-sized humanoid robots without human-like proportions. A small-sized humanoid robot with human-like proportions has not been studied because of the absence of such a small humanoid. It should be noted that human-like proportions play a very important role in enhancing the presence of an operator through an avatar. In our previous work, a small-sized humanoid robot named MH-2 was developed for wearable telepresence system. The MH-2 consists of seven degrees-of-freedom (7-DOF) arms, a 3-DOF head, and a torso scaled according to human-like proportions. Wire–pulley mechanisms were employed to achieve a compact design to adopt a requirement for wearability. In this work, a telepresence system is introduced for the evaluation of the communication ability of the MH-2. In the experiment, Skype, using a flat display, was compared with the MH-2. The “Indian Poker” game was employed for the experiment. It is an ideal evaluation platform because it is a psychological game that requires careful observations among the players. The evaluations were conducted in terms of six aspects: emotion or personality, line of sight, familiarity, presence, enjoyment, and smoothness of the game progress. The experimental results showed that the MH-2 performed positively in two out of six aspects, namely the line of sight and smoothness of the game progress. On the other hand, facial expressions play important role to display individual presence. From a comprehensive standpoint, the MH-2 demonstrated good capabilities for rich remote communications.     

Real-time interaction with a humanoid avatar in an immersive table tennis simulation

In this paper, we report on the realization of an immersive table tennis simulation. After describing the hardware necessities of our system, we give insight into different aspects of the simulation. In particular, the developed methods for collision detection and physical simulation are presented. The design of the virtual opponent is of crucial importance to realize an enjoyable game. Therefore, we report on the implemented game strategy and the animation of the opponent. Since table tennis is one of the fastest sports, the synchronization of the human player's movements and the visual output on the projection wall is a very challenging problem to solve. To overcome the latencies in our system, we designed a prediction method that allows high speed interaction with our application     

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.     

Stepping over obstacles with humanoid robots

The wide potential applications of humanoid robots require that the robots can walk in complex environments and overcome various obstacles. To this end, we address the problem of humanoid robots stepping over obstacles in this paper. We focus on two aspects, which are feasibility analysis and motion planning. The former determines whether a robot can step over a given obstacle, and the latter discusses how to step over, if feasible, by planning appropriate motions for the robot. We systematically examine both of these aspects. In the feasibility analysis, using an optimization technique, we cast the problem into global optimization models with nonlinear constraints, including collision-free and balance constraints. The solutions to the optimization models yield answers to the possibility of stepping over obstacles under some assumptions. The presented approach for feasibility provides not only a priori knowledge and a database to implement stepping over obstacles, but also a tool to evaluate and compare the mobility of humanoid robots. In motion planning, we present an algorithm to generate suitable trajectories of the feet and the waist of the robot using heuristic methodology, based on the results of the feasibility analysis. We decompose the body motion of the robot into two parts, corresponding to the lower body and upper body of the robot, to meet the collision-free and balance constraints. This novel planning method is adaptive to obstacle sizes, and is, hence, oriented to autonomous stepping over by humanoid robots guided by vision or other range finders. Its effectiveness is verified by simulations and experiments on our humanoid platform HRP-2.     

基于单目摄像头的人形机器人实时导航系统

提出一种用于室内环境下人形机器人的实时导航系统。首先基于颜色特征,把单目图像的像素点分类为地面和障碍物,并对各个障碍物的像素点进行聚类,以选择出它们最底部的像素点作为特征点。然后基于SVM(Support Vector Machine)算法,构造摄像头中实际点和像素点坐标的映射关系,并用均值场理论辅助SVM的学习过程。根据映射关系和特征像素点,就可以估计出障碍物与机器人的距离。最后根据距离信息,在离散化的运动空间中,一步一步规划出机器人的行走路径。在人形机器人DARWIN上对提出的方法进行了实现,实验结果显示了该方法的有效性。     

Studying laughter in combination with two humanoid robots

To let humanoid robots behave socially adequate in a future society, we started to explore laughter as an important para-verbal signal known to influence relationships among humans rather easily. We investigated how the naturalness of various types of laughter in combination with different humanoid robots was judged, first, within a situational context that is suitable for laughter and, second, without describing the situational context. Given the variety of human laughter, do people prefer a certain style for a robot??s laughter? And if yes, how does a robot??s outer appearance affect this preference, if at all? Is this preference independent of the observer??s cultural background? Those participants, who took part in two separate online surveys and were told that the robots would laugh in response to a joke, preferred one type of laughter regardless of the robot type. This result is contrasted by a detailed analysis of two more surveys, which took place during presentations at a Japanese and a German high school, respectively. From the results of these two surveys, interesting intercultural differences in the perceived naturalness of our laughing humanoids can be derived and challenging questions arise that are to be addressed in future research.     

An investigation of climbing up stairs for an inchworm robot

In this research, an inchworm-type robot is being developed for the purpose of rescue missions. This robot has the ability to traverse obstacles such as stairs with fewer joints than legged robots. A self-standing inchworm robot, which has five links and four joints, is produced for trial purposes. In order for this robot to be able to climb up stairs, the kinematical analysis and the development of the program were investigated. As a result, the effectiveness of this robot is confirmed experimentally.     

Modeling of humanoid dynamics including slipping with nonlinear floor friction

Biped locomotion created by controlling methods based on zero-moment point has been realized in real world and been well verified its efficacy for stable walking. However, the walking strategies that have been proposed so far seems to avoid such considerations as slipping of foot on the floor, even though there should exist the slipping large or small in real world. In this research, a dynamical model of humanoid robot including slipping of foot is proposed, which is derived by the Newton–Euler method. To confirm the veracity of the derived dynamical model, the model has been verified from the view point that when all friction coefficients are identical to zero, the total kinetic energy should be conserved to be unchanged, and when the coefficients are not zero, the total kinetic energy should decrease monotonously.     

Momentum control with hierarchical inverse dynamics on a torque-controlled humanoid

Hierarchical inverse dynamics based on cascades of quadratic programs have been proposed for the control of legged robots. They have important benefits but to the best of our knowledge have never been implemented on a torque controlled humanoid where model inaccuracies, sensor noise and real-time computation requirements can be problematic. Using a reformulation of existing algorithms, we propose a simplification of the problem that allows to achieve real-time control. Momentum-based control is integrated in the task hierarchy and a LQR design approach is used to compute the desired associated closed-loop behavior and improve performance. Extensive experiments on various balancing and tracking tasks show very robust performance in the face of unknown disturbances, even when the humanoid is standing on one foot. Our results demonstrate that hierarchical inverse dynamics together with momentum control can be efficiently used for feedback control under real robot conditions.     

Measurement and comparison of humanoid H7 walking with human being

This paper describes our research efforts aimed at understanding human being walking functions. Using a motion-capture system, force plates and distributed force sensors, walk motion of both human being and humanoid H7 was captured. Experimental results are shown. Comparisons in between human being and H7 walk made using the following characteristics: (1) ZMP trajectories; (2) torso movement; (3) free leg trajectories; (4) joint angle usage; (5) joint torque usage. Furthermore, implications of the comparisons to the humanoid robot are discussed.     

Walking pattern generation for a humanoid robot with compliant joints

This work presents a walking pattern generator based on the control of the center of mass (COM) states and its experimental validations on the compliant humanoid robot COMAN powered by intrinsically compliant joints. To cope with the inaccuracies of the joint position tracking resulted by the physical compliance, the proposed pattern generator uses the feedback states of the COM and on-line computes the updated COM references. The position and velocity of the COM are the state variables, and the constrained ground reaction force (GRF) limited by the support polygon is the control effort to drive the real COM states to track the desired references. The frequency analysis of the COM demonstrates its low frequency spectrum that indicates the demand of a low control bandwidth which is suitable for a robot system with compliant joints. The effectiveness of the proposed gait generation method was demonstrated by the experiments performed on the COMAN robot. The experimental data such as the COM position and velocity tracking, the GRF applied on feet, the measured step length and the walking velocity are analyzed. The effect of the passive compliance is also discussed.     

Automatic generation of ladder diagram with control Petri Net

This paper presents a design method to generate a ladder diagram (LD) automatically with the control Petri Net (CPN) for control of discrete event system. This method describes the specification of a practical system with the CPN that associates operations with places and conditions with transitions. Based on the firing regulation of transition, the relationship of places, conditions, and events are formulated with Boolean functions. These functions can be easily converted into LD and implemented on a programmable logic controller (PLC). An application example in a liquid mixture system shows that the proposed method is effective and has the advantages of ease of understanding, modification, and maintenance.