Life-size humanoids which have the same joint arrangement as humans are expected to help in the living environment. In this case, they require high load operations such as gripping and conveyance of heavy load, and holding people at the care spot. However, these operations are difficult for existing humanoids because of their low joint output. Therefore, the purpose of this study is to develop the highoutput life-size humanoid robot. We first designed a motor driver for humanoid with featuring small, water-cooled, and high output, and it performed higher joint output than existing humanoids utilizing. In this paper, we describe designed humanoid arm and leg with this motor driver. The arm is featuring the designed 2-axis unit and the leg is featuring the water-cooled double motor system. We demonstrated the arm's high torque and high velocity experiment and the leg's high performance experiment based on water-cooled double motor compared with air-cooled and single motor. Then we designed and developed a life-size humanoid with these arms and legs. We demonstrated some humanoid's experiment operating high load to find out the arm and leg's validity.

Human knee joint has a yaw-axis rotational DOF and a locking mechanism called screw-home mechanism. We focus on this mechanism and implement it to a musculoskeletal humanoid through hardware design. The importance of developing a knee joint with screw-home mechanism is that such a joint is capable of working yaw-axis properly and generating enough pitch joint torque for supporting whole body motion. In this paper, as an evaluation of our developed knee joint, we first checked the moment arm of the yaw rotational axis of the knee. Moreover, we also checked the yaw angle displacement during squat motion. From these results, we confirmed that the mechanism worked properly. Second, in order to check whether enough pitch joint torque is generated during movement, we conducted several experiments with whole body motions such as squatting. Lastly, as unique and integrated motions that involve the use of yaw DOF derived from the mechanism, we tested knee joint Open-Close, Right-to-Left and whole body twist squat motion. Our results demonstrated the feasibility of musculoskeletal humanoids with screw-home mechanism and showed that we have achieved humanlike twisting motion.

This paper presents a design methodology for humanoid upper limb based on human anatomy. Kenshiro is a full body tendon driven humanoid robot and is designed from the data of average 14 year old Japanese boy. The design of his upper limb is realizing detail features of muscles, bones and the adhesive relation of the two. Human mimetic design is realized by focusing on the fact that joints are being stabled by muscles winding around the bones, and by accurately mimicking the bone shape this was enabled. In this paper we also introduce details of mechanical specifications of the upper limb. By having muscles, bones, and joint structures based on human anatomy, Kenshiro can move flexibly. The use as human body simulator can be expected by measuring sensor data which can correspond to biological data.

In order to know human dynamics, humanoid as a human body simulator is increasing its importance. Such humanoid is expected to have human musculoskeletal structure as close as possible. From this viewpoint, we are trying to create new musculoskeletal humanoid which has detailed human imitating structure, such as bi-articular muscle, muscle arrangement, joint structure and so on. In this paper, we address the design of lower thigh. The concepts of the thigh include leg configuration, new knee joint and link, and artificial muscle arrangements, especially knee joint structure imitating human flexible motion. The knee joint has yaw axis DOF and its locking mechanism which is usually simplified in robotics. Finally, we conduct extension, flexion and rotation as basic experiment to confirm the joint characteristics. Also, we conduct rotation experiment in the ground state to confirm the contribution of yaw axis DOF for human-like motion.

To design a robot with humanlike body structure, this paper presents a design methodology for a humanoid upper limb by tendon driven system. We newly designed an upper limb and rib cage like thorax for a musculoskeletal humanoid robot, based on the knowledge of anatomy. The robot consists of muscle, bone, and joint structure based on human and is expected to move flexibly and dynamically. This paper describes how to design such an upper limb and proposes the key mechanical design points, which is “rib surface thorax”, “muscle cushion”, “planar muscle”, and “open type ball joint”. To show that these mechanisms is effective in making a musculoskeletal humanoid robot, we examine the motion range of the robot. One of our goals is to enable robots to do the same movements as humans do through mimicking the human body structure, finding some important elements of human nature. This robots explained in this paper is the prototype for a new life size robot “Kenshiro” project.

We have been developing and studying musculoskeletal humanoids. Our goal is to realize more human-like humanoids which can do natural and dynamic motions as well as humans. Especially motions with complex contact with environments, which is jumping, running, catching a ball, and landing on one's hands, etc, are difficult to be achieved by humanoids. To achieve that motions, robots have to absorb shock force so as not to break ones' body structures, such as gears, motors, body links and so on. Musculo-skeletal humanoids are suited for these situations, because they can easily have mechanical flexibilit for shock absorption by adding elastic units, which is nonlinear spring units, to its own tendons. In this paper, we propose shock absorption methods by musculoskeletal humanoids, which uses its own mechanical flexibilit and simple refle of each muscles based on tension sensor. This strategy is inspired by human's motion control, and it can achieve shock absorption tasks without any fast sensor feedback controls and any prediction ocntrols used by conventional robots with rigid bodies. We chose a catching a ball task as an example of complex contact motions, implemented the proposed strategy to musculoskeletal humanoid Kenzoh and confirme the feasibility of proposed method by actually catching a ball demonstration.

A walking biped robot is required to change its walking direction and speed with minimal delay and not to tip off even when subjected to an unexpected external force. A major drawback of Zero Moment Point (ZMP) based online walking pattern generation methods is that arbitrary ZMPs cannot be achieved without divergence of the Conter of Mass (CoM). In this paper, we propose a new online walking trajectory generation method that utilizes nondivergence conditions of ZMP-CoM in a successive manner. This method enables changes in the walking direction and speed of a robot and push recovery under an unknown external force in unifie form. Experiments confir walking change of up to 4.05 km/h in the speed and changes in the walking direction with minimum delay and successful push recovery under an implse of 22 Ns.

In this paper we propose a “Direct-Mapping Method” and describe a wearable device which has a similar muscle arrangement as a tendon-driven humanoid robot. This device has linear-encoders as many as the muscles of the robot to control, and they are arranged like the robot's muscle alignment. Tendon-driven humanoids have advantages of their human size, multiple Degrees of freedoms and their musclo-skeletal structure, therefore they are able to make more human-like poses than shaft-driven humanoid robots. If we can teach human poses to them, they become more human-like so that we feel a sense of familiarity with robots. However, because of their complex structure, sometimes they make incorrect poses. There must be a feedback system to control their bones in detail. To make human-like pose naturally and to make precise motion by feed back to the user, the best way may be a wearable device. With this device, we can control tendon-driven humanoids without making their simulation model in the computer. We discuss the hardware settings of the device and the controlling system in this paper. Experiments of controlling a tendon-driven humanoid were conducted to demonstrate the effectiveness of the device. When controlling the robot, a situation that some muscles are loose or too tight occured. However, this device's behavior-teaching framework contributes to detailed robotic movement in the future.

Many humanoids have been developed, but more complicated and flexible humanoids must be developed, in order to realize more natural and various motions like humans. However, it is difficult to measure directly joint posture in the multi-dofs joint of such robots (e.g. a hip spherical joint) because of its complicated structure. This paper describes an estimation method for tendon-driven joint postures of these complicated multi-dofs joints, only based on information of muscles' length relative displacement data during joints movement. We regard this posture estimation problem as a pattern matching problem in the mapping space from joint posture to muscle lengths and solve this problem by using very simple searching algorithms. Furthermore, this paper describes a strategy for deciding muscles motor command to acquire its joint proprioception by the proposed joint posture estimation method only based on information of muscles' length relative displacement data. Finally, we confirmed the feasibility of the proposed estimation method by applying this algorithm to the real tendon-driven musculoskeletal humanoid Kojiro.

The high power ability of humanoid is desired for application of nursing or running or jumping motions. Achievement of the actuator of light and powerful equivalent to humans is required. In this paper, we propose a method to extract inherent performance from motors by an active temperature control. The method safely improves the output of motors. The active temperature control is achieved by combining the estimation of an internal temperature of the motor with the forced cooling by liquid. We also developed high power motor drivers for the proposed method. An experiment of a high power joint test bench is shown. In this paper, we show a high power prototype biped robot for application of nursing, running or jumping motions. High power actuator system and robust internal body network are developed for high power robot. Basic demonstration experiments of high power motion are shown.

A method of giving intelligence to control robots by human navigations is one of appropriate solution to respond to a lot of unforeseeable situations, and making movement of complicated robots in contact condition with surroundings is not easy. In this research, a bilateral wearable device using stiffness adjustable muscle actuator modules is developed in order to control robots, feel external force of robots and teach motion that contact on surroundings. For an experiment it was realized maneuvering a musculo-skeletal humanoid, it could feedback humanoid's external force to manipulator and its force feedback by bilateral control leads manipulator to do safety contact motion.

We are developing the novel musculoskeletal humanoid that is able to do coordinated motion with arms, legs and spine. In this research, we present how to realize largely bending/extending motion while standing using spine and hip joints of a fullbody musculoskeletal humanoid, which has a complicated body like a human, such as over 90 muscles and about 60 DOFs. And we propose how to generate coordinated motions of spine and hip joints and how to control such a complicated humanoid in order to keep standing during its motion. Furthermore, we confirmed that this robot could bend/extend its spine and hip joints coordinately while standing by some experiments.

Humanoid robots are still in a process of the evolution. We are trying to develop a next-generation which have safety, flexibility and multiplicity of uses. A shoulder structure is one of the keystone, because it controls arms and end effectors and it have direct contact with humans and daily life environments. We have designed new shoulder structure following the scapula-collarbone structure for a muscle-driven humanoid robot named ldquoKojirordquo (Fig. 1)[1]. We consider that the scapula-collarbone structures have the following merits, 1)wide range of movement, 2)flexible shoulder like humans, 3)safety from the driving system, 4)allowing space for a lot of parts inside the thorax. The shoulder structure is consisted of scapula, collarbone, upper-arm and thorax. We have devised the spherical shape thorax and scapula structure which realizes desired scapula motions. In this paper, we describe the design process and operation test of the shoulder structure.

High physical ability of humanoid robots is desired for application to nursing care. Light and powerful actuators are required to realize the high-power performance. In this paper, we propose a method to bring out maximum performance of electric motors aggressively. The technique of motor core temperature estimation and control improves the motor power performance dramatically but safely without motor burnout. We have developed high power motor driver modules for the proposed method and equipped them into our humanoid robot and prototype jumping robot. High-power performance experiments with the robots demonstrate our method.

This paper presents how to develop a lower body with both redundant and high-powered actuator systems toward the next version of a fully tendon-driven musculoskeletal humanoid, which will be able to realize various flexible motions using whole body. The newly developed lower body has 44 actuators and each actuator can generate 25[kgf] muscle force continually. We propose the new design method of hollowing out the parts assembly areas, which realizes easy design of the skeleton with massive actuators. Finally we presented an experiment on the hip muscles tension and redundancy performances during the hip joint rotation motion.

This paper presents the concepts, issues on development, and future perspectives of a novel musculoskeletal humanoid `Kotaro'. The specifications and advantages of Kotaro include muscle-driven endoskeletal structure, multiple degrees of freedom, variable physical softness, the multiple-joint spine, easily configurable muscles, distributed onbody controllers, various sorts of many sensors including eyes, ears, and whole-body tactile sensors, and so on. These characteristics would achieve a flexible body, litheness of motions, safety, and adaptability and applicability to diverse tasks which would very often appear in human's daily lives

We have been studying about muscle-tendon spined humanoid robots for aiming a novel humanoid robot that has modifiable mechanical flexibility, safety and wide variety of postures. This paper describes a new concept of reinforceable-muscle humanoid and the development of a new musculo-skeletal humanoid robot named "Kenji" that is a prototype muscle-driven humanoid next to previous developed humanoid "Kenta". Kenji has 140 actuators in total and numerous multi-modal sensors. This paper also presents some experiments that show the feasibility of the robot.

We are trying to create an innovative humanoid which has increased flexibility by imitating the structure of a human shoulder, especially the shoulder blade. We designed a flexible shoulder structure for a muscle-driven humanoid robot which has the following merits, 1) wide range of movement and flexible shoulder like humans, 2) having the shoulder structure built on to the outside of the chest, allowing space for a lot of parts inside the chest. We developed a prototype humanoid robot named "Blade" which has a musculo-skeletal humanoid torso with the shoulder blade, driven by motor-actuated tendons. This paper describes the advantages of the structure of the shoulder blade, the development of a humanoid with the shoulder blade, and some experiments showing its range of movement using the prototype humanoid robot we presented.

We propose a concept of reinforceable-muscle humanoid with hyper parallel muscle-tendon systems. By the facilitation of changing the assignment of actuators, we can easily strengthen a specific part of robot body, while changing the arrangement of actuators of current humanoid robots is quite difficult. By developing muscle units in each of which a motor and sensors are integrated, and by adopting musculo-skeletal structure, the rearrangeability of muscles has been realized. This paper describes the concept, prototype design and implementation of the reinforceable muscle humanoid, and the evaluating experiment by a musculo-skeletal humanoid is presented.