35 accepted papers
The objective of constrained motion planning is to connect start and goal configurations while satisfying task-specific constraints. Motion planning becomes inefficient or infeasible when the configurations lie in disconnected regions, known as essentially mutually disconnected components (EMDs). Co…
Real-time sampling-based planners increasingly use learned sampling distributions for faster planning in autonomous vehicles. These planners employ a neural network to predict the optimal path and bias some samples toward the path. However, inherent prediction inaccuracies of the network often lead …
This study introduces a novel assembly, layered peg-in-hole, and suggests a search strategy. Distinct from the traditional peg-in-hole assembly, where two workpieces (i.e., peg/hole) are present, the layered peg-in-hole assembly contains three workpieces (i.e., peg, hole, and thru-hole). To handle t…
With the growing employment of learning algorithms in robotic applications, research on reinforcement learning for bipedal locomotion has become a central topic for humanoid robotics. While recently published contributions achieve high success rates in locomotion tasks, scarce attention has been dev…
This paper presents an active control strategy for lower limb exoskeletons by proposing an end-to-end framework employing deep reinforcement learning (DRL) to enable smooth transitions between different movement patterns. The majority of existing methods in exoskeleton literature employ finite state
For successful peg-in-hole assembly, predefined sub-tasks should be executed sequentially according to the current contact state. Therefore, recognizing contact state transitions is essential in order to determine whether to continue the current task or proceed to the next. In that context, learning
While legged robots have achieved significant advancements in recent years, ensuring the robustness of their controllers on unstructured terrains remains challenging. It requires generating diverse and challenging unstructured terrains to test the robot and discover its vulnerabilities. This topic r
In this paper, as an approach to stabilize humanoid walking where the height of CoM varies, a Novel Model Predictive Control framework based on three dimensional Divergent Component of Motion (3D-DCM) is proposed. To ensure the feasible utilization of contact forces for maintaining humanoid balance,
This contribution presents a robot path-following framework via Reactive Model Predictive Contouring Control (RMPCC) that successfully avoids obstacles, singularities and self-collisions in dynamic environments at 100 Hz. Many path-following methods rely on the time parametrization, but struggle to
The avatar robot is a robot capable of realistic remote operation. In remote operation, the controllability of the glove is crucial. This glove can manipulate the hand interacting directly with the environment at the remote site. The glove must be able to accurately estimate the hand posture and pro…
As compliant joints not only compensate for the lack of actuated degrees of freedom of an under-actuated system and improve grasp stability but also prevent system failure from unexpected contacts, various types of compliant joints have been applied to end-effectors. Although joint compliance increa
Recently, foot stepping strategies of humanoid robots have been actively developed for robust balancing of humanoids against disturbances. In this paper, a novel stepping algorithm adjusting double support phase (DSP) time is proposed. First, the stepping algorithm is proposed based on a model predi…
Door traversal is an essential task for a mobile manipulator to achieve autonomous navigation in indoor environment. However, it remains challenging since it requires the coupled motion of the robot and door and is composed of several sub-problems such as approaching, opening, passing through, and c
The estimation of external joint torque and contact wrench is essential for achieving stable locomotion of humanoids and safety-oriented robots. Although the contact wrench on the foot of humanoids can be measured using a force-torque sensor (FTS), FTS increases the cost, inertia, complexity, and fa…
This study proposes a realtime motion planning framework that leverages the prediction of a portion of the optimal trajectory for sampling-based anytime planning algorithms. Existing algorithms predict the entire optimal path and bias random samples toward it for fast path planning. However, these a…
In this letter, we review the question of which action space is best suited for controlling a real biped robot in combination with Sim2Real training. Position control has been popular as it has been shown to be more sample efficient and intuitive to combine with other planning algorithms. However, f
Recently, the robotic assembly has been expanded into an unstructured environment. This environment includes uncertainties that may cause unexpected situations such as a failure of the assembly. Such problems can be prevented or monitored by a robust contact state (CS) estimation method. In that sen
Maintaining balance to external pushes is one of the most important features for a humanoid to walk in a real environment. In particular, methods for counteracting to pushes using the centroidal angular momentum (CAM) control have been actively developed. In this paper, a CAM control scheme based on…
In this study, a mechanism that realizes a novel structural form of the harmonic reducer is introduced. Conventional robots often use various mechanical reducers owing to low torque and high-speed characteristics of electric motors. Among them, harmonic reducers are frequently used because of their…
This letter proposes a novel learned feasibility estimator that considers multi-modal grasp poses for grasp and motion planning. Grasp poses inherently have multi-modal structures, that is, continuous and discrete parameters. Mixed-integer programming (MIP) is one method that solves these multi-moda
Stable contact and safe responses to the collision have been studied to develop interactive robots such as service and collaborative robots. Stable and safe interactions are usually achieved through the inherent compliance of a motion controller with external torque estimation. However, a fixed cont…
This paper proposes a novel and practical approach to enhance the computational efficiency of the hierarchical quadratic programming (HQP)-based whole-body control. The HQP method is known to offer control solutions satisfying strict priority with various constraints for multiple-tasks execution. Ho…
As robots begin to collaborate with people in real life, safety needs to be rigorously ensured to reliably employ robots nearby. In addition to collision prevention algorithms, studies are being actively conducted on collision handling methods. Momentum Observer (MOB) was developed to estimate distu…
The actuator bandwidth limitation deteriorates the stability and performance of torque-based robot controllers. Operational space control is especially prone to this problem, since the limited bandwidth of a single actuator can reduce the performance of all related tasks simultaneously. In this arti…
The peg-in-hole method using the compliance characteristics of robots has advantages in terms of cost and speed compared to conventional methods based on contact force feedback with force/torque sensors. In our previous study, we proposed a compliant peg-in-hole assembly method based on blind search
This paper proposes a 6 degree of freedom (DoF) manipulator for haptic application. The proposed haptic device, named GHap, is designed based on the four-bar-linkage mechanism for linear motion with the ring-type gimbal mechanism. To improve the force display ability, the device is designed to compe…
Electric motors, with a fixed reduction ratio, have a large unused operating region when mimicking muscle movements owing to the difference between the force-velocity curves of electric motors and muscles. This unused region can be reduced by changing the reduction ratio according to the external fo
Robots with high degrees of freedom (DoFs), such as humanoids and mobile manipulators, are expected to perform multiple tasks simultaneously. Hierarchical quadratic programming (HQP) can effectively compute a solution for strictly prioritized tasks. However, the continuity of the control input is no
The compliant motion of humanoid robots is one of their most important characteristics for interacting with humans and various environments in the real world. During walking, compliant motion ensures stable contact between the foot and ground, but walking stability is degraded by position tracking p…
Torque controlled robots have the capability of implementing compliant behavior with back-drivability. In practice, however, joint elasticity often prevents an accurate position tracking performance of a robot. In particular, humanoid robots are influenced more by elasticity because of a long kinema…
Actuator modules of humanoid robots have relatively higher joint elasticity than those of industrial robots. Such joint elasticity could lead to negative effects on both the tracking performance and stability for walking. Especially, unstable contact between the foot and ground caused by joint elast…
Reactivity to unexpected situations is one of the most important characteristics of walking for real world applications. In this study, we introduce a reactive biped robot walking method that reflects only the current state of the robot. Therefore, time plan and trajectory tracking control are not r…
The Operational Space Formulation (OSF) from the 1980s is probably the most frequently applied task-space controller in robotics. In multipriority control of redundant robots via the OSF, a feedback linearization is performed on the first hierarchy level while lower-priority tasks are executed in th
Low back pain is one of the world's most serious health problems. Conservative methods are recommended for back pain, and stabilization exercise as one of these methods has been proven to be effective. The “big 3” exercises are proven stabilization exercises, and it is able to train most of the musc…
Autonomous vehicles are actively being developed from ADAS(Advanced Driver Assistance Systems) toward fully autonomous vehicles. Motion planning is one of the most important key technologies for fully autonomous vehicles, especially when they are operated in constrained narrow space such as parking…