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Kunio Kojima

33 accepted papers

2026

Development of Adaptive-Limb Transformable Robot for Portable and Replaceable End-Effectors With Compact Lock-Spin Mechanisms

RA-L 2026

Transformable robots adapt to various environments by changing their shape or functionality. The robots are able to further expand their task range by replacing their end-effectors (EEs). In this paper, we propose an adaptive-limb transformable robot capable of replacing multiple types of mounted EE

Cited by 0SourceScholar
2026

Development of Adaptive-Limb Transformable Robot for Portable and Replaceable End-Effectors with Compact Lock-Spin Mechanisms

ICRA 2026poster

Transformable robots adapt to various environments by changing their shape or functionality. The robots are able to further expand their task range by replacing their end-effectors (EEs). In this paper, we propose an adaptive-limb transformable robot capable of replacing multiple types of mounted EE…

Cited by 0SourceScholar
2025

Development of Variable Chain Motor with Shape and Speed-Torque Characteristics Variability and Its Application to a Humanoid

IROS 2025

Various methods have been proposed to achieve high output torque and a wide output range for fast and high-load robotic motions. However, in robots composed of slender frames, such as humanoid robots, the limited space available for actuators and transmission components restricts the application of

Cited by 0SourceScholar
2025

Trajectory Generation for Humanoid Backflips and Jumps Based on Whole-Body Dynamics Optimization with Consideration of KKT Residual Convergence

IROS 2025

For trajectory generation of whole-body jumping motions such as humanoid backflips, it is crucial to simultaneously optimize the takeoff, flight, and landing phases while considering full-body dynamics and kinematics. Although such methods have been proposed for standard jumping motions, they have n

Cited by 0SourceScholar
2024

Design of Upper-Limb Exoskeleton with Distal Branching Link Mechanism for Bilateral Operation of Humanoid Robots

IROS 2024poster

Exoskeletons for robot operation necessitate shoulders with high range of motions and high degrees of freedom to fit the operator’s shoulder girdle. These shoulder joints need high torque for force feedback on the operator. Existing exoskeletons struggle to simultaneously meet these requirements of…

Cited by 0SourceScholar
2024

HumanMimic: Learning Natural Locomotion and Transitions for Humanoid Robot via Wasserstein Adversarial Imitation

ICRA 2024poster

Transferring human motion skills to humanoid robots remains a significant challenge. In this study, we introduce a Wasserstein adversarial imitation learning system, allowing humanoid robots to replicate natural whole-body locomotion patterns and execute seamless transitions by mimicking human motio…

Cited by 33SourceScholar
2024

Magnetic tactile sensor with load tolerance and flexibility using frame structures for estimating triaxial contact force distribution of humanoid

IROS 2024poster

For humanoid whole body contact motions, it is important to recognize the existence of whole body contacts and the contact forces. The challenges in recognizing the existence of whole body contacts and the contact forces in life-size humanoids are: 1) the measurement part with low mechanical strengt…

Cited by 0SourceScholar
2024

WARABI Hand: Five-fingered Robotic Hand with Flexible Skin and Force Sensors for Social Interaction

ICRA 2024poster

A robotic hand for social interaction should be capable of comfortable touch with humans. However, it is difficult to mount skin, tactile sensors, and driving mechanism required for human contact, especially holding hands, on a slender finger. In addition, in order to unitize the hand for easy use w…

Cited by 1SourceScholar
2023

Development of a Whole-Body Work Imitation Learning System by a Biped and Bi-Armed Humanoid

IROS 2023poster

Imitation learning has been actively studied in recent years. In particular, skill acquisition by a robot with a fixed body, whose root link position and posture and camera angle of view do not change, has been realized in many cases. On the other hand, imitation of the behavior of robots with float…

Cited by 3SourceScholar
2023

Humanoid Walking System with CNN-Based Uneven Terrain Recognition and Landing Control with Swing-Leg Velocity Constraints

IROS 2023poster

In order for a humanoid robot to traverse uneven terrain without falling over, the robot must control its landing position appropriately. To determine the landing position, there are two difficulties in terrain recognition and leg motion control. In terrain recognition, it is difficult to recognize…

Cited by 0SourceScholar
2023

Whole-Body Torque Control Without Joint Position Control Using Vibration-Suppressed Friction Compensation for Bipedal Locomotion of Gear-Driven Torque Sensorless Humanoid

IROS 2023poster

Humanoids operate in repeated contact and non-contact with their environment and so the motion of humanoids such as walking on uneven terrain or in a narrow space requires the accurate force and position control. Joint torque control systems are suitable for position and force control, but are prone…

Cited by 0SourceScholar
2023

ZMP Feedback Balance Control of Humanoid in Response to Ground Acceleration

IROS 2023poster

In order for a humanoid robot to balance on the movable ground, balance feedback control in response to its unpredictable movement is required. However, feedback control in response to ground movement has the following two issues, (A) Interaction between the ground dynamics and the balance control m…

Cited by 3SourceScholar
2022

RAMIEL: A Parallel-Wire Driven Monopedal Robot for High and Continuous Jumping

IROS 2022poster

Legged robots with high locomotive performance have been extensively studied, and various leg structures have been proposed. Especially, a leg structure that can achieve both continuous and high jumps is advantageous for moving around in a three-dimensional environment. In this study, we propose a p…

Cited by 10SourceScholar
2022

Robust Humanoid Walking System Considering Recognized Terrain and Robots' Balance

IROS 2022poster

When robots walk on uneven terrain, trajectory planning should take into account both the whole-body dy-namics and the ground geometry simultaneously. In uneven terrain environments, there are only a limited number of places where the robot is able to make stable contact with the ground without its…

Cited by 6SourceScholar
2021

Drop Prevention Control for Humanoid Robots Carrying Stacked Boxes

IROS 2021poster

We developed a method to enable a humanoid robot to carry stacked boxes. In order to transport objects efficiently, it is necessary to carry multiple objects at the same time, but in previous studies, humanoid robots have only been able to carry a single object. When a humanoid robot carries stacked…

Cited by 8SourceScholar
2021

Dynamic Fall Recovery Motion Generation on Biped Robot With Shell Protector

RA-L 2021

Fall recovery after falling over is a critical feature for biped robots that work in the real world. We propose a method by considering robot joint angle trajectory as a multivariable function of time and orientation of robot root links. Compared with the conventional method, our method required les

Cited by 10SourceScholar
2021

Fixed-root Aerial Manipulator: Design, Modeling, and Control of Multilink Aerial Arm to Adhere Foot Module to Ceilings using Rotor Thrust

ICRA 2021poster

Precise aerial manipulation is important for multirotor robots. For multirotors equipped with arms, the root pose error due to the floating body affects the precision at the end effector. Fixed-root approaches, such as perching on surfaces using the rotor suction force, are useful to address this pr…

Cited by 2SourceScholar
2020

Bilateral Humanoid Teleoperation System Using Whole-Body Exoskeleton Cockpit TABLIS

RA-L 2020

We describe a system design approach for the bilateral teleoperation of a humanoid robot. We have focused on bipedal stability and 2D/3D locomotion space problems. Our proposed system has two robot hardware and two control software. The master side hardware is newly developed seat-type whole-body ex

Cited by 70SourceScholar
2020

Drive-Train Design in JAXON3-P and Realization of Jump Motions: Impact Mitigation and Force Control Performance for Dynamic Motions

IROS 2020poster

For mitigating joint impact torques, researchers have reduced joint stiffness by series elastic actuators, reflected inertia by low gear ratios, and friction torque from drive-trains. However, these impact mitigation methods may impair the control performance of contact forces or may increase motor…

Cited by 9SourceScholar
2020

Fast Tennis Swing Motion by Ball Trajectory Prediction and Joint Trajectory Modification in Standalone Humanoid Robot Real-time System

IROS 2020poster

In this work, we propose a system for humanoid robot fast motions. When a humanoid robot performs a motion such as a tennis forehand stroke motion, a whole-body fast motion in reaction to visual information is required. There are three problems to tackle. (1) Motion is desired to be quick. (2) Real-…

Cited by 10SourceScholar
2020

Footstep Modification Including Step Time and Angular Momentum Under Disturbances on Sparse Footholds

RA-L 2020

Maintaining dynamic balance is an important requirement for bipedal robots. To deal with large disturbances, the footsteps need to be modified depending on the disturbance. Currently, there are few methods that determine footsteps by considering foothold constraints and the balance of the robot. In

Cited by 22SourceScholar
2020

Online System for Dynamic Multi-contact Motion with Impact Force Based on Contact Wrench Estimation and Current-Based Torque Control

IROS 2020poster

Humanoid robots are expected to play a big role at distress sites and disaster sites. There is a variety of multi-contact locomotion forms other than bipedal walking such as crawling through tightly, getting on the rubble by using its knees and elbows, or jumping in and rolling over the obstacles. I…

Cited by 4SourceScholar
2019

Autonomous Safe Locomotion System for Bipedal Robot Applying Vision and Sole Reaction Force to Footstep Planning

IROS 2019poster

Humanoid robots are expected to conduct tasks on behalf of humans in places such as a disaster scattered environment. Although humanoid robots have potentials to walk on uneven ground unlike wheeled robots, it is difficult to reach a given destination without falling down based on only visual inform…

Cited by 5SourceScholar
2019

Extended Three-Dimensional Walking and Skating Motion Generation for Multiple Noncoplanar Contacts With Anisotropic Friction: Application to Walk and Skateboard and Roller Skate

RA-L 2019

In this letter, we propose a three-dimensional (3-D) walking and skating motion generation method to achieve sequential walking and skating motion with skateboard and roller skate. For generating the sequential stable skating motion using a passive wheel, we must deal with non-coplanar contacts with

Cited by 12SourceScholar
2019

Humanoid Robot’s Force-Based Heavy Manipulation Tasks with Torque-Controlled Arms and Wrist Force Sensors

IROS 2019poster

We present a torque controller for humanoid robot's arm and a method to execute heavy-load tasks under that controller. Torque control of arms can reduce the joint load when an impulsive force is applied to the robot's hand. This feature is important for robots that will work among many humans or ob…

Cited by 2SourceScholar
2018

High Speed Whole Body Dynamic Motion Experiment with Real Time Master-Slave Humanoid Robot System

ICRA 2018poster

In this paper, we propose novel methods suitable for online real time whole body master-slave control with real life-sized humanoid robot. We conducted some dynamic whole body master-slave experiment with life-sized humanoid robot, and we achieved speedier and flexible master-slave operation compare…

Cited by 39SourceScholar
2017

3D walking and skating motion generation using divergent component of motion and gauss pseudospectral method

IROS 2017poster

This paper presents a COM trajectory generation method for 3D walking and skating motion by nonlinear optimization. In our method, we solve the following problems: (1) dealing with both walking and skating motion in the same framework, (2) generating center of mass (COM) trajectory faster than execu…

Cited by 6SourceScholar
2017

Bipedal oriented whole body master-slave system for dynamic secured locomotion with LIP safety constraints

IROS 2017poster

In this study, we propose a novel method to operate whole body of a humanoid robot, which also includes both feet, dynamically and safely with the master-slave approach. The conventional whole body master-slave approaches need static balancing assumption or a certain time length of planning after op…

Cited by 26SourceScholar
2017

Bipedal walking control against swing foot collision using swing foot trajectory regeneration and impact mitigation

IROS 2017poster

For humanoid robots, unexpected collision can cause instability of robot balancing and damage to both robots and environment. This paper presents a reactive bipedal walking controller against swing foot collision for humanoid robots. This controller is composed of following three components: 1) Swin…

Cited by 9SourceScholar
2017

Rotational Sliding Motion Generation for Humanoid Robot by Force Distribution in Each Contact Face

RA-L 2017

Recent studies have explored humanoid robots in contact with the environment in various ways. However, many of them assumed static rather than sliding contacts. Studies on humanoid shuffle motion planning have realized sliding motions, such as turning, but relied on quasi-static balance control. In

Cited by 8SourceScholar
2016

Real-time skating motion control of humanoid robots for acceleration and balancing

IROS 2016poster

In this paper, we propose a real-time control method for skating motion of humanoid robots. There are three problems for skating motion: (1) keeping dynamic balance, (2) adequately controlling foot force to suppress slipping at the foot, (3) controlling full-body motion in real-time. For solving the…

Cited by 17SourceScholar
2016

Walking control in water considering reaction forces from water for humanoid robots with a waterproof suit

IROS 2016poster

In this paper, we develop a waterproof suit for humanoid robots and propose an underwater walking control method. Although very few life-sized humanoid robots are completely waterproof, we can easily make these humanoid robots watertight by putting a waterproof suit on them. In water, humanoid robot…

Cited by 21SourceScholar
2015

Shuffle motion for humanoid robot by sole load distribution and foot force control

IROS 2015poster

In situations where humanoid robots with constrained posture walk through a narrow space (e.g. manufacturing plants and kitchens), shuffling motions that are stepless and possess wide foot supporting area are effective. One of the difficulties of humanoid's shuffle translations is the load distribut…

Cited by 18SourceScholar