31 accepted papers
In conventional learning-based robotic dynamics modeling, physical information is mostly incorporated into the model or loss function, while the design of training data often relies on random sampling or uniform coverage, which can limit performance. To address this gap, this paper proposes the CATA…
This paper presents a data-driven control optimization framework for flexible joint robots (FJR) based on frequency response function (FRF) data, enabling automated controller synthesis without explicit model identification. Unlike conventional model-based approaches that rely on accurate parameter
This paper presents a data-driven control optimization framework for flexible joint robots (FJR) based on frequency response function (FRF) data, enabling automated controller synthesis without explicit model identification. Unlike conventional model-based approaches that rely on accurate parameter …
The performance of robot actuators is still primarily evaluated using manufacturer-provided static specifications such as maximum torque and rated speed. However, these metrics are insufficient for assessing dynamic behaviors that are essential for physical interaction, including backdrivability, tr…
Accurate dynamics modeling is crucial for achieving precise Ground Reaction Force (GRF) control and high-performance legged locomotion. However, real-world legged systems exhibit strong frictional effects with hysteresis and inter-joint coupling, which conventional static friction models or purely d
Robotic gantry stages are a prevalent class of industrial robots used for precise positioning tasks in various fields, including semiconductor manufacturing, 3D printing, and automated assembly. However, these systems often exhibit time-varying dynamics because the position of the end-effector (i.e.
This paper presents a robust control algorithm for precise orientation control of robot manipulators using a disturbance observer (DOB) specifically designed for orientation dynamics. Our approach addresses the challenges of 3D orientation control by incorporating various orientation representations
Applications involving serial manipulators, in both co-manipulation with humans and autonomous operation tasks, require the robot to render high admittance so as to minimize contact forces and maintain stable contacts with high-stiffness surfaces. This can be achieved through admittance control, how
Control techniques like MPC can realize contact-rich manipulation which exploits dynamic information, maintaining friction limits and safety constraints. However, contact geometry and dynamics are required to be known. This information is often extracted from CAD, limiting scalability and the abilit…
Research on interactive force measurement in robotics follows two trends: distributed force sensing using soft tactile sensors and centered force sensing using rigid sensors. This study proposes a novel force sensing mechanism and algorithm to integrate the two approaches taking advantage of a soft
This paper presents a novel, nonlinearity robust identification method for deriving the inertia matrix of multi-DOF Flexible Joint Robots (FJR), utilizing resonance and anti-resonance frequencies in the Frequency Response Functions (FRF). Our proposed method overcomes the limitations of conventional…
Industrial robots have increased payload, repeatability, and reach compared to collaborative robots, however, they have a fixed position controller and low intrinsic admittance. This makes realizing safe contact challenging due to large contact force overshoots in contact transitions and contact ins…
This paper presents a periodic running control strategy based on a modified Spring-Loaded Inverted Pendulum (SLIP) model to achieve stable running at various velocities. While the traditional SLIP model is valued for its simplicity and intuitive representation of running dynamics, its limitations im
Series Elastic Actuator (SEA) has widely been used in various robotic applications due to its ability to provide safe and accurate force. However, conventionally, securing the high torque sensitivity of the SEA of the spring is challenging due to the limitation of natural frequency and torque capaci
In this letter, a new robust approach is proposed to address the limitation of impedance rendering for Series Elastic Actuators (SEA). The concept of Elastic Structure Preserving (ESP) control allows for the attachment of desired load-side dynamics to the SEA while maintaining a passivity condition,
Recent research on quadruped robots has been achieving high-performance motion control based on optimization and reinforcement learning (RL). However, there is still ongoing research aimed at demonstrating that implementing high-performance motion based on simple and dominant dynamic principles is p
Control of tasks by Flexible Joint Robots (FJR) is highly susceptible to disturbances, coupling, and vibrations that result from joint elasticity. A possible solution to this problem is a Disturbance Observer (DOB), which can address these issues in the joint space. However, this approach has limita
Admittance and impedance controllers are often purely feedforward, using measured external force or motion, respectively, to generate a reference for an inner-loop controller. In this case, the range of dynamics which can be rendered is limited by the inner-loop, which causes, e.g. contact stability…
The use of impedance control has become widespread in applications requiring simultaneous position tracking and compliance in contact. However, disturbances such as friction and model uncertainties can adversely affect the performance of impedance-based motion control. The disturbance observer (DOB)…
This paper presents a comprehensive comparative study of the multisensor-based force observers for accurate force control. A force controlled system which contains a force sensor for measuring force transmitted to the load by the motor and an encoder for measuring motor position is considered as the…
Legged robots have opened their way to more stable and practical mobile robot applications. However, their locomotion strategies are limited to similar patterns, and dynamic running at high speed still is not successfully realized. One of the key technology required for the realization of the dynami…
It is necessary for a robotic leg to behave like a spring to realize a periodic hopping, since it can be efficient and does not require complicated control algorithm. However, the impact force makes the realization of periodic hopping more challenging. In this letter, an optimal landing strategy for
In many series-elastic actuator applications, the ability to safely render a wide range of impedance is important. Advanced torque control techniques such as the disturbance observer (DOB) can improve torque tracking performance, but their impact on safe impedance range is not established. Here, saf…
This paper proposes a practical and less conservative passivity analysis for series elastic actuators (SEAs) by introducing load port definition and shows that the achievable stiffness by the impedance control of SEA can be set higher than the inherent stiffness of SEA depending on the condition of…
In this paper, a novel mobile robot developed to perform Curling sports is introduced. The developed robot is a Stone Throwing Robot (STR) for Curling that can travel on the ice with wheels and throw a stone as well as make curls of the stone. The STR is developed as a robot component of an Artifici…
In this paper, Dynamic Dumbbell, a novel robotic device for advanced muscular exercise of upper limb is presented. The type of exercise load is classified and designed in terms of mechanical engineering to be implemented in Dynamic Dumbbell. The exercise load model, which is named as programmable ex…
This paper proposes a novel parallel robot - Virtual Ground Robot (VGR) - that is driven by three Series Elastic Actuators (SEAs) to interact with a human. The proposed Virtual Ground Robot provides a virtual ground on which a human can stand on and interact in three directions: the pitch, the roll…
This letter presents an enhanced external torque estimation algorithm for series elastic actuators (SEAs) expanding the usability of the residual-based technique. Although the residual method demonstrates online torque estimation capability in diverse applications and thus becomes popular, it is pra
In this paper, elastically actuated bi-articular manipulator is developed using a novel compact planetary geared elastic actuator. The newly developed SEA, which is compact and has little backlash, can achieve high force control performance. The configuration of the developed manipulator is designed…
The tension control of wires can benefit from Series Elastic Actuator (SEA), which is a potential emerging actuator system. In this paper, it is verified that the tension of wires can be successfully controlled by a novel SEA, called Compact Planetary-geared Elastic Actuator (cPEA), which incorporat…
This paper describes a wire-driven parallel robotic system for the maintenance of offshore wind turbines. This robotic system vertically climbs on towers or blades, and performs cleaning and inspection using waterjets and phased array ultrasonic testing (PAUT) devices, respectively. For a detailed m