M. Morisawa

National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan

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Publications (46)8.48 Total impact

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    ABSTRACT: This paper tries to improve a balance control based on the Capture Point (CP) control. First the characteristics of the conventional balance controller are shown to be essentially the same as the CP controller. Then we analyze the transfer function of the balance controller. We introduce a new state variable with the CP integration to the CP and the ZMP (Zero-Moment Point) in order to trim a long term offset of the CP and the ZMP. Verification of the proposed balance controller is conducted through both simulation and experiments with a humanoid robot HRP-2[11].
    Humanoid Robots (Humanoids), 2012 12th IEEE-RAS International Conference on; 01/2012
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    ABSTRACT: This paper presents an external force observer that estimates the external force acting on a biped humanoid robot, such as a collision force with a human or with an object. Since biped humanoid robots balance themselves on a limited area with foot soles, the detection of external force is important to realize for a stable balance controller for humanoid robots working in a real environment. In the proposed observer, the external force is estimated using inertial sensors and foot force sensors based on simple but efficient modeling of the forces applied to the robot. This paper also shows the experiments of the proposed external force observer using a real humanoid robot HRP-2. The experimental results show that the proposed observer has satisfactory performance to estimate the external force with sufficient response and accuracy.
    01/2012;
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    ABSTRACT: We discuss a feedback controller to stabilize biped walking which has toe support phase mimicking human gait. Using a reference walking pattern proposed in our previous work [11], our stabilizer can realize reliable walking. To evaluate the quality of stabilization, we propose two indicators, the maximum floor reaction force and the root mean square of the CoM tracking error. From our walking experiments, these indicators suggest us two policies of control parameter tuning, (1) not to control ZMP at toe support, and (2) not to use the ZMP phase-lead compensation for sagittal motion. These findings were validated by simulations of linear inverted pendulum model. It is shown that the observed behavior of the controller is caused by large velocity dissipation at support exchange.
    Humanoid Robots (Humanoids), 2012 12th IEEE-RAS International Conference on; 01/2012
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    ABSTRACT: In this paper, we develop a humanoid robot HRP-3χ where a multi-fingered hand is attached to the original HRP-3. By installing the visual recognition module for a single camera and the grasp planning module for the multi-fingered hand to the control software, HRP-3χ can recognize the position/orientation of the object and can calculate its grasping posture at online. Here, visual recognition module of a single camera is shown to be efficient. The effectiveness of the proposed HRP-3χ is confirmed by experimental result in which the robot achieves bipedal walk, visual recognition, and multiple finger grasp.
    11th IEEE-RAS International Conference on Humanoid Robots (Humanoids 2011), Bled, Slovenia, October 26-28, 2011; 01/2011
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    ABSTRACT: A model of a walking pattern imitating human motion is presented. An accurate imitation of human motion and a robust bipedal walking motion are, however, hardly realized together. We therefore focus on only three characteristics of human walking motion: single toe support, knee stretching, and swing leg motion. Based on a conventional pattern generator, single toe support is added, waist height is changed in order to stretch the knees as much as possible, and swing leg motion is generated approximating the human's motion. The generated motion is then filtered to provide a feasible pattern. In addition, the stabilizer is improved in order to keep the Zero Moment Point (ZMP) within the tiny support polygon during the single support phase with toe link. Finally, we successfully demonstrate the generated walking pattern with the robot HRP-4C.
    2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2011, San Francisco, CA, USA, September 25-30, 2011; 01/2011
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    ABSTRACT: This paper presents the development of humanoid robotics platform - 4 (or HRP-4 for short). The high-density implementation used for HRP-4C, the cybernetic human developed by AIST, is also applied to HRP-4. HRP-4 has a total of 34 degrees of freedom, including 7 degrees of freedom for each arm to facilitate object handling and has a slim, lightweight body with a height of 151 (cm) and weight 39 (kg). The software platform OpenRTM-aist and a Linux kernel with the RT-Preempt patch are used in the HRP-4 software system. Design concepts and mechanisms are presented with its basic specification in this paper.
    2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2011, San Francisco, CA, USA, September 25-30, 2011; 01/2011
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    ABSTRACT: This paper describes a biped walking control method for a collision of a swinging foot on uneven terrain. Because a swing leg moves to a desired landing position, an unexpected collision on a terrain may be happened by a distance error between a foot and a terrain. A swing foot has to not only absorb a impact force, but also changes a trajectory as long as a swing foot contacts on a terrain. Furthermore it is required to keep a balance against a contact force. To prevent a trip over and a losing balance by contact on a terrain, two reactive key components are installed: 1) Set appropriate impedance gains of the feet according to a walking phase, 2) Update the desired landing position to the COG (Center of Gravity) pattern generation immediately as a detecting/releasing contact. In this paper, focused on a swing motion, a robust biped walking with a collision of a swinging foot on a uneven terrain is realized. The proposed method is validated through simulation results with the HRP-2 humanoid robot.
    11th IEEE-RAS International Conference on Humanoid Robots (Humanoids 2011), Bled, Slovenia, October 26-28, 2011; 01/2011
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    ABSTRACT: Hardware improvement of cybernetic human HRP-4C for entertainment is presented in this paper. We coined the word "Cybernetic Human" to explain a humanoid robot with a realistic head and a realistic figure of a human being. HRP-4C stands for Humanoid Robotics Platform-4 (Cybernetic human). Its joints and dimensions conform to average values of young Japanese females and HRP-4C looks very human-like. We have made HRP-4C present in several events to search for a possibility of use in the entertainment industry. Based on feedback from our experience, we improved its hardware. The new hand, the new foot with active toe joint, and the new eye with camera are introduced.
    2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2011, San Francisco, CA, USA, September 25-30, 2011; 01/2011
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    ABSTRACT: We have developed a humanoid robot (a cybernetic human called “HRP-4C”) which has the appearance and shape of a human being, can walk and move like one, and interacts with humans using speech recognition. Standing 158 cm tall and weighing 43 kg (including the battery), with the joints and dimensions set to average values for young Japanese females, HRP-4C looks very human-like. In this paper, we present ongoing challenges to create a new business in the contents industry with HRP-4C.
    Advanced Robotics and its Social Impacts (ARSO), 2010 IEEE Workshop on; 11/2010
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    ABSTRACT: A novel framework of biped walking stabilization control is introduced. The target robot is a 42 DOF humanoid robot HRP-4C which has a body dimensions close to the average Japanese female. We develop a body posture controller and foot force controllers on the joint position servo of the robot. By applying this posture/force control, we can regard the robot system as a simple linear inverted pendulum with ZMP delay. After a preliminary experiment to confirm the linear dynamics, we design a tracking controller for walking stabilization. It is evaluated in the experiments of HRP-4C walking and turning on a lab floor. The robot can also perform an outdoor walk on an uneven pavement.
    Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on; 11/2010
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    ABSTRACT: This paper proposes a reactive leg motion generation method which integrates geometric constraints into its generation process. In order to react given instructions instantaneously or to keep balance against external disturbances, feasible steps must be generated automatically in real-time for safety. In many cases this feasibility has been realized by using predefined steps or admissible stepping regions. However, these predefinitions are often too conservative or valid only in limited situations. The proposed method considers geometric constraints in addition to joint limits during its generation process and it can utilize the ability of the robot to a maximum extent. It can generate feasible walking pattern in real-time by modifying the swing leg motion and the next landing position at each control cycle. The proposed method is validated by experiments using a humanoid robot HRP-2.
    Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on; 11/2010
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    ABSTRACT: This paper proposes a new framework to recover balance against external forces by combining disturbance suppression and reactive stepping. In the view point of the feedback control, a reactive step can help to diminish the disturbance caused by an external force that should be compensated to maintain balance. In other words, if the adequate step is performed, the feedback controller does not have to compensate all of the external force by itself. Under this concept, we propose an original solution to distribute the compensation between a feedback controller and a reactive step, according to the period of support phase and a disturbance characteristic. We first clearly distinguish between the role of the disturbance suppression and the reactive stepping. Then, based on this distinction, the small disturbance of external force or happening late during the single-support phase, is mainly suppressed by state feedback. The large disturbance which is out of capability by feedback controller and at the beginning of the single-support phase, is absorbed by modifying reactively the next steps. The proposed method is validated through experimental results with the HRP-2 humanoid robot.
    Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on; 11/2010
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    ABSTRACT: In this paper, we propose a framework on planning collision-free walking motion for biped humanoid robots. Our proposed planner is composed of two phases. In the first phase, the constraint condition is generated as a function of time by using the walking pattern generator. In the second phase, the collision-free walking motion is planned. To generate the collision-free motion, we add a time parameter to each milestone of the single-query, bidirectional, lazy collision checking planner in order to explicitly consider the time-parametrized constraint conditions. Further, we smoothen the generated path by using B-spline interpolation. Through experimental results, we show that our planner is effective in realizing collision-free walking motion by real humanoid robots.
    IEEE/ASME Transactions on Mechatronics 11/2010; · 3.14 Impact Factor
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    ABSTRACT: This paper presents preliminary results and analysis on generating turning motion of a humanoid robot by slipping the feet on the ground. Humans unconsciously exploit the fact that our feet slip on the ground; such slip motion is necessary for humanoids so as to realize sophisticated human-like motions. In order to generate the slip motion, we need to predict the amount of slip. We propose the hypothesis that the turning motion is caused by the effect of minimizing the power generated by floor friction. A model of rotation by friction force is described on the basis of our hypothesis. The case that a robot applies the same force on both feet is discussed; then, we extend the discussion to the case of different force distribution. The hypothesis is verified through experiments with a humanoid robot HRP-2.
    Robotics and Automation (ICRA), 2010 IEEE International Conference on; 06/2010
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    ABSTRACT: This paper proposes a feasible pattern generation method for humanoid robots. One of the difficulties in pattern generation for humanoid robots is that generated patterns must satisfy many constraints such as physical limits, self-collision and so on to be feasible in addition to constraints to achieve a specified task. In reality, some of these constraints are not often taken into account during the pattern generation and they are just checked afterwards and unsatisfied constraints are fixed by hand. It is not easy to find a parameter set to get a feasible motion for humanoid robot and these pattern generators need to be used carefully when they are used online. The proposed method integrates the feasibility constraints into the pattern generation algorithm and enables to use it online more safely and releases human from parameter tuning. Moreover, a stiffness varying constraint is introduced to improve the feasibility.
    Humanoid Robots, 2009. Humanoids 2009. 9th IEEE-RAS International Conference on; 01/2010
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    ABSTRACT: This paper presents preliminary results on generating walking and turning motion of a humanoid robot based on human motion data obtained by using motion capturing system. The target humanoid robot is recently released HRP-4C, which looks like a Japanese woman with realistic geometry. One of the main uses of this robot is to be entertainment. Therefore it is important that the robot's motions are easily created, and feasible for the robot. Captured human motion data are used as a starting point, to which the following modifications are added: step length, speed, rotational angle during turn, and so on. Dynamic balance is also considered. Verification is conducted through both simulation and experiment with HRP-4C. A turning performance based on human motion is successfully demonstrated.
    Humanoid Robots, 2009. Humanoids 2009. 9th IEEE-RAS International Conference on; 01/2010
  • Conference Paper: Cybernetic human HRP-4C
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    ABSTRACT: The development of cybernetic human HRP-4C is presented in this paper. The word ¿cybernetic human¿ is a coinage for us to explain a humanoid robot with a realistic head and a realistic figure of a human being. HRP-4C stands for humanoid robotics platform-4 (cybernetic human). Standing 158 [cm] tall and weighting 43 [kg] (including batteries), with the joints and dimensions set to average values for young Japanese females, HRP-4C looks very human-like. This paper introduces the design process, mechanical features, and electrical features with specifications of HRP-4C.
    Humanoid Robots, 2009. Humanoids 2009. 9th IEEE-RAS International Conference on; 01/2010
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    ABSTRACT: HRP-4C is our novel biped humanoid robot whose body shape and face appearance are quite similar to those of female humans. It can make not only various whole body motions including biped locomotion but also various facial motions using eleven axes joints inside the head. This paper focuses on the face of HRP-4C, the mechanical structure of it and the software system for creating its facial motions. To make creation process of the facial motions easy and efficient is one of the important technologies for the practical use of the robot. Our system allows controlling the face of actual robot from the graphical user interface running on a client PC with the high responsiveness. This feature enables a creator to efficiently edit detailed facial motions with powerful functions including overdub loop edit, key pose sequence edit with the lip-sync mode, and automatic blinking. By using this system, we were able to rapidly make facial motions for the demonstrations of HRP-4C.
    Humanoid Robots, 2009. Humanoids 2009. 9th IEEE-RAS International Conference on; 01/2010
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    2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, October 18-22, 2010, Taipei, Taiwan; 01/2010
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    ABSTRACT: In this paper, we generate the biped gait of a humanoid robot that looks like a human's one. To generate the human like motion, we first capture walking motion of a human. Then, we analyze the captured data and obtain several information such as the relationship between the step length and waist height etc. We consider applying these informations to the real humanoid robot. Also, when the human walks, the sway of the waist is smaller than most of the humanoid robot's one. By compensating the angular momentum of the robot and by modifying the ZMP trajectory, we show that sway of the robot's waist can be smaller. We show the effectiveness of the proposed method through simulation and experimental results.
    Intelligent Robots and Systems, 2009. IROS 2009. IEEE/RSJ International Conference on; 11/2009