scispace - formally typeset
Search or ask a question
Author

Ryosuke Tajima

Bio: Ryosuke Tajima is an academic researcher from Toyota. The author has contributed to research in topics: Personal robot & Robot control. The author has an hindex of 11, co-authored 24 publications receiving 415 citations.

Papers
More filters
Proceedings ArticleDOI
12 May 2009
TL;DR: An implementation of fast running motions involving a humanoid robot using a motion generation and a balance control and a human-sized humanoid robot that can run forward at 7.0 [km/h] is presented.
Abstract: The present paper describes an implementation of fast running motions involving a humanoid robot. Two important technologies are described: a motion generation and a balance control. The motion generation is a unified way to design both walking and running and can generate the trajectory with the vertical conditions of the Center Of Mass (COM) in short calculation time. The balance control enables a robot to maintain balance by changing the positions of the contact foot dynamically when the robot is disturbed. This control consists of 1) compliance control without force sensors, in which the joints are made compliant by feed-forward torques and adjustment of gains of position control, and 2) feedback control, which uses the measured orientation of the robot's torso used in the motion generation as an initial condition to decide the foot positions. Finally, a human-sized humanoid robot that can run forward at 7.0 [km/h] is presented.

184 citations

Proceedings ArticleDOI
Ryosuke Tajima1, Keisuke Suga1
01 Oct 2006
TL;DR: A novel method of determining the center of mass (COM) and foot locations is proposed that is independent of the target robot actuators or assignments of joints, and allows an on-line system to be built easily and is useful for actual robots.
Abstract: In the present paper, we introduce a new method by which to generate motions having flight phases such as jumping or running. Such motions are expected to expand the speed and stability of legged robots. Motions with flight phases are examined with respect to jumping, stability and implementation. A novel method of determining the Center of Mass (COM) and foot locations is proposed that is independent of the target robot actuators or assignments of joints. Moreover, the proposed method allows an on-line system to be built easily and is useful for actual robots. A one-legged jumping robot having a toe joint is built in order to demonstrate the feasibility of this method. Using the toe joint of the robot, the proposed method can reduce the angular velocities of the joints remarkably. Experiments are conducted to investigate the control of the direction, velocity and turning of the robot.

43 citations

Patent
12 Sep 2008
TL;DR: In this article, a legged robot performs motion by changing a joint angle, which includes a trajectory generating section to calculate a center-of-gravity trajectory in designated stepping motion from the stepping motion including at least one of walking motion, running motion and stopping motion.
Abstract: There is provided a legged robot that performs motion by changing a joint angle, which includes a trajectory generating section to calculate a center-of-gravity trajectory in designated stepping motion from the stepping motion including at least one of walking motion, running motion and stopping motion, and generate a center-of-gravity trajectory by superimposing a designated travel velocity onto a travel velocity of a center of gravity in the calculated center-of-gravity trajectory in stepping motion, and a trajectory updating section to store the generated center-of-gravity trajectory and update all the stored center-of-gravity trajectories so as to be continuous, and a trajectory reproducing section to calculate time-varying data of a target value of the joint angle based on the updated center-of-gravity trajectory, and a joint driving section to rotate a joint of the legged robot based on the calculated time-varying data of a target value of the joint angle.

30 citations

Proceedings ArticleDOI
Noriaki Hirose1, Ryosuke Tajima1
01 May 2017
TL;DR: The modeling of rolling friction based on a Recurrent Neural Network (RNN) using Long Short-Term Memory (LSTM) is proposed to precisely express the rolling friction characteristics to achieve a better model.
Abstract: The modeling and identification of a mechanical system is the most important issue for many control systems in order to realize the desired control specifications. In particular, the friction characteristics often deteriorate the control performance, such as in the fast and precise positioning performance in industrial robots, the force estimation accuracy based on a disturbance observer, and the posture control performance of an inverted pendulum robot. Rolling friction tends to cause overshoot, undershoot, or limit cycles of the target value in positioning systems. In previous research, some model structures for rolling friction have been proposed to express the hysteresis characteristics in order to overcome these control issues. However, it is difficult to identify the correct parameters for precise modeling. In this paper, the modeling of rolling friction based on a Recurrent Neural Network (RNN) using Long Short-Term Memory (LSTM) is proposed to precisely express the rolling friction characteristics. The initial value design of the RNN during supervised learning is also presented to achieve a better model. The effectiveness of the proposed approach is verified by comparison with conventional friction models using an actual experimental setup.

26 citations

Proceedings ArticleDOI
01 Sep 2015
TL;DR: A human-following method based on model predictive control is proposed to realize the contradicting requirements of both shortening the relative distance between the owner and the robot and ensuring no collision.
Abstract: Advanced countries are currently experiencing an aging society, and many people could benefit from a personal robot that can support a comfortable lifestyle. However, excessive and premature robot assistance may deteriorate the user's physical abilities and can accelerate their aging process. The authors have already proposed a personal robot that can follow the user, even on uneven road surfaces. Therefore, people utilizing this personal robot do not need to carry heavy baggage, even after shopping. It is reported that a few brisk walks per week can be advantageous to our health management and can improve our quality of life, so this means that the personal robot can encourage the user to maintain an active lifestyle. For this personal robot, close following is required to ensure the safety of the baggage and the personal robot. However, it is difficult for the conventional approach to avoid collisions when the user stops suddenly. In this paper, a control approach based on model predictive control is proposed to achieve two conflicting requirements: close following and no collision. The proposed approach predicts multiple future outcomes, in which the user either stops or accelerates in the next step, in order to realize an appropriate relative distance and to consider the upper and lower boundaries for posture stabilization. The effectiveness of the proposed approach can be verified in numerical simulations using a multibody dynamics model consisting of actual 3D representations.

19 citations


Cited by
More filters
Journal ArticleDOI
01 Aug 2011
TL;DR: In this article, a hydraulically powered quadruped robot (HyQ) was developed to serve as a platform to study not only highly dynamic motions, such as running and jumping, but also careful navigat...
Abstract: A new versatile hydraulically powered quadruped robot (HyQ) has been developed to serve as a platform to study not only highly dynamic motions, such as running and jumping, but also careful navigat...

602 citations

Proceedings ArticleDOI
09 May 2011
TL;DR: R2's integrated mechatronic design results in a more compact and robust distributed control system with a fraction of the wiring of the original Robonaut, making it a far more valuable tool for astronauts.
Abstract: NASA and General Motors have developed the second generation Robonaut, Robonaut 2 or R2, and it is scheduled to arrive on the International Space Station in early 2011 and undergo initial testing by mid-year. This state of the art, dexterous, anthropomorphic robotic torso has significant technical improvements over its predecessor making it a far more valuable tool for astronauts. Upgrades include: increased force sensing, greater range of motion, higher bandwidth, and improved dexterity. R2's integrated mechatronic design results in a more compact and robust distributed control system with a fraction of the wiring of the original Robonaut. Modularity is prevalent throughout the hardware and software along with innovative and layered approaches for sensing and control. The most important aspects of the Robonaut philosophy are clearly present in this latest model's ability to allow comfortable human interaction and in its design to perform significant work using the same hardware and interfaces used by people. The following describes the mechanisms, integrated electronics, control strategies, and user interface that make R2 a promising addition to the Space Station and other environments where humanoid robots can assist people.

408 citations

Proceedings ArticleDOI
10 Oct 2009
TL;DR: Methods to decompose and synthesize a running gait pattern into vertical, horizontal and rotational components so that time-dependent ground friction limits are satisfied and running at 10 km/h is achieved on a real robot whose dimension are same as ASIMO.
Abstract: Bipedal running can easily result in a fall due to poor availability of the ground reaction force at the boundary of the flight and support phases. We propose methods to decompose and synthesize a running gait pattern into vertical, horizontal and rotational components so that time-dependent ground friction limits are satisfied. We also extend previously proposed boundary condition, the divergent component of motion, for switching walking gait patterns into running which involves vertical acceleration of the center of gravity. Using these techniques, running at 10 km/h is achieved on a real robot whose dimension are same as ASIMO.

285 citations

Proceedings ArticleDOI
01 Nov 2014
TL;DR: This paper gives an overview on the torque-controlled humanoid robot TORO, which has evolved from the former DLR Biped, and describes its mechanical design and dimensioning, its sensors, electronics and computer hardware.
Abstract: This paper gives an overview on the torque-controlled humanoid robot TORO, which has evolved from the former DLR Biped. In particular, we describe its mechanical design and dimensioning, its sensors, electronics and computer hardware. Additionally, we give a short introduction to the walking and multi-contact balancing strategies used for TORO.

240 citations

Proceedings ArticleDOI
01 Dec 2009
TL;DR: The design process, mechanical features, and electrical features with specifications of HRP-4C, a humanoid robot with a realistic head and a realistic figure of a human being, are introduced.
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.

230 citations