Yuki Asano

Design concept of detail musculoskeletal humanoid “Kenshiro” - Toward a real human body musculoskeletal simulator

We have developed and studied musculoskeletal humanoids. Our goal is to realize a more human-like humanoid as a real human simulator, which has the same muscle and joint arrangements as humans and can do natural and dynamic motions as well as humans. Especially, it is very challenging to design musculoskeletal structure which can contain a large number of high powered muscles. Now, we design new fullbody musculoskeletal humanoid Kenshiro. This paper presents the concepts of this new robot and also shows the outline of our latest results Kenshiro, which is the succeeding version of our previous robot Kojiro.

Design methodology for the thorax and shoulder of human mimetic musculoskeletal humanoid Kenshiro -a thorax structure with rib like surface -

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.

Lower thigh design of detailed musculoskeletal humanoid “Kenshiro”

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.

Design Approach of Biologically-Inspired Musculoskeletal Humanoids

In order to realize more natural and various motions like humans, humanlike musculoskeletal tendon-driven humanoids have been studied. Especially, it is very challenging to design musculoskeletal body structure which consists of complicated bones, redundant powerful and flexible muscles, and large number of distributed sensors. In addition, it is very challenging to reveal humanlike intelligence to manage these complicated musculoskeletal body structure. This paper sums up life-sized musculoskeletal humanoids Kenta, Kotaro, Kenzoh and Kenshiro which we have developed so far, and describes key technologies to develop and control these robots.

Design of upper limb by adhesion of muscles and bones — Detail human mimetic musculoskeletal humanoid kenshiro

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.

Achievement of twist squat by musculoskeletal humanoid with screw-home mechanism

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.

A sensor-driver integrated muscle module with high-tension measurability and flexibility for tendon-driven robots

We propose a sensor-driver integrated muscle module by integrating necessarily components for tendon-driven robot which is likely to complicate. The module has abilities of high-tension measurability and flexible tension control. In order to achieve flexible tension control, we developed the new tension measurement mechanism with high-tension measurability and the new motor driver which enables current based motor control. We demonstrate the tension control ability of the module by several experiments. Furthermore, utilizing the module advantage of design facilitation, we made two types of tendon-driven robots and confirmed effectiveness of the module.

Biomimetic design of musculoskeletal humanoid knee joint with patella and screw-home mechanism

We are trying to create a novel musculoskeletal humanoid robot which has a humanlike structure. In this paper, we present a new knee joint which is usually simplified in robotics for high controllability. The knee joint has three human mimetic points, patella, screw-home mechanism and four-linked linkage. Patella is for a longer moment arm. Screw-home mechanism is for locking knee joint. Four-linked linkage is for making humanlike motion. Furthermore, we confirmed those performances by three experiments.

Human mimetic musculoskeletal humanoid Kengoro toward real world physically interactive actions

We have been developing human mimetic musculoskeletal humanoids from the view point of human-inspired design approach. Kengoro is our latest version of musculoskeletal humanoid designed to achieve physically interactive actions in real world. This study presents the design concept, body characteristics, and motion achievements of Kengoro. In the design process of Kengoro, we adopted the novel idea of multifunctional skeletal structures to achieve both humanoid performance and humanlike proportions. We adopted the sensor-driver integrated muscle modules for improved muscle control. In order to demonstrate the effectiveness of these body structures, we conducted several preliminary movements using Kengoro.

Learning nonlinear muscle-joint state mapping toward geometric model-free tendon driven musculoskeletal robots

To control a musculoskeletal tendon-driven robot we propose a novel method to learn musculoskeletal nonlinear bidirectional mapping between muscle length and posture (joint angle) from a real musculoskeletal robot. We show the nonlinear musculoskeletal mapping from joint angle to muscle length can be learned as a linear combination of simple nonlinear functions. This formulation can be extended to posture estimation (mapping from muscle length to joint angle) by EKF (Extened Kalman Filter) and torque estimation by differentiation in a musculoskeletal robot. In this paper, we applied the method to tendon driven musculoskeletal robots and verified the validity.