42 accepted papers
A class of planar bipedal robots with unique mechanical properties has been proposed, where all links are balanced around the hip joint, preventing natural swinging motion due to gravity. A common property of their equations of motion is that the inertia matrix is a constant matrix, there are no non…
Impulse-driven limbless robots offer a promising platform for locomotion in environments where body deformation or complex actuation is undesirable. Prior work has shown that symmetric designs can achieve net displacement through temporally asymmetric internal actuation, yet such systems often exhib
Rimless wheel, one of the simplest walking models, has been widely studied as a theoretical framework for bipedal locomotion. This study introduces a dual rimless wheel (DRW) connected by elastic elements for maintaining the body shape and investigates its passive locomotion capability through numer…
Since the late 19th century when the first walking toys were developed, it has been known that mechanical stoppers at the hip joint are crucial for generating stable passive dynamic walking. Recent research on passive-dynamic and limit-cycle walkers has also confirmed that mechanical stoppers at the…
A control method is proposed for a tensegrity robot to generate legged-rolling locomotion (i.e., rolling movement produced by a legged system). The robot has a minimal structure composed only of two rods and four elastic cables. The difficulty of the control arises from the minimalistic structure th…
This study introduces a novel burrowing robot that achieves effective locomotion inside granular media through the synergistic integration of high-frequency vibration-induced environmental-phase-transition (EPT) and adaptive morphing. The robotic system employs three key innovations: 1) an asymmetri
Quadrupedal locomotion involves coordinated interaction between limbs and torso, enabling them to achieve remarkable movement performance and adapt effectively to various environments. In previous studies, mathematical dynamic models of quadrupeds have been established to investigate the mechanisms
Quadrupeds exhibit remarkable locomotion performance through the coordination between their limbs and torso. From past biological knowledge, it is understood that during walking, the forelimbs primarily contribute to braking, while the hindlimb are responsible for propulsion. However, in the field o
This paper proposes a novel passive dynamic walker with a body shape similar to an eight-legged rimless wheel that performs a natural swinging motion of the swing leg through storage and release of elastic energy. The generated motion is period-1 and asymptotically stable, but the inherent limit cyc
This paper investigates the mathematical modeling and basic motion properties of planar seven-link robots that forms passive closed and active open chains. The passive closed model is formed by connecting seven rigid frames via seven viscoelastic joints, and the active open model is formed by connec
The authors have proposed a passive rotating locomotion robot that forms a convex heptagonal body by connecting seven identical linear rigid frames via viscoelastic rotational joints. In our previous study, it was confirmed through both numerical simulations and actual experiments that stable and pa
A control method is proposed for a tensegrity robot to generate legged-rolling locomotion (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i>, rolling movement produced by a legged system). The robot has a minimal structure composed only of two
This paper addresses the problem of realizing a novel robotic bipedal locomotion called wheel gait, which is achieved by rotating the stance and swing legs in the same direction. First, a model of a planar 3-DOF X-shaped walker with a reaction wheel is introduced, and the mathematical equations are…
Inspired by the fascinating underwater locomotion of cephalopods such as octopuses, this research explores the possibility of using legged robots in underwater environments. Using a rimless wheel model, we investigated their navigation and adaptation capabilities in a dynamic fluid environment. Thro…
In the natural world, benefited from the advantages of the spine, quadrupeds exhibiting extraordinary flexibility which allowing them to move efficiently on variable terrains. The previous researches have indicated the legged robots which efficiently utilizing their spine can achieve rapid and stabl…
The quadrupeds have wider active territory than humans. Their bodies can adapt various environments through evolution, enabling the efficient, elegant gait for their legged locomotion. Previous researches have indicated lots of examples of utilizing the advantages of body to achieve environment adap…
The movement of the legs involves the interaction between the feet and the ground. Consequently, most animals possess a wide variety of foot morphologies and multifunctional capabilities. The selection and switching of these foot functions are passive and environment-dependent, ensuring environmenta…
This paper introduces a novel X-shaped walker with telescopic legs and investigates its control method with the aim of generating a stable wheel gait on a horizontal plane without including zero dynamics which is essentially unstable and difficult to stabilize. First, we outline a planar 6-DOF robot…
We have been investigating a crawling-like loco-motion robot to make it efficiently slide forward based on a simple system and control mechanisms on a slippery level surface, where the motion of the center of mass plays an important role. In this paper, we induce an effective motion of the center of…
This paper presents a water walking robot with 6 feet which consists of a rimless wheel and a flywheel, and has a foot attached to the tip of each leg. First, in order to make the robot walk on water, we propose a foot control method by imitating the legs of some animals that can walk on water. Seco…
This paper proposes novel passive-dynamic walk-ers formed by two cross-shaped frames and eight viscoelastic elements. Since it is a combination of two four-legged rimless wheels via viscoelastic elements, we call it viscoelastically-combined rimless wheel (VCRW). Two types of VCRWs consisting of dif…
Particular tasks performed in narrow and confined spaces require a capability of passing through a limited pathway. Consequently, previous research developed a snake-like robot that generates a 1-D rectilinear gait with an appropriate mechanical design. In contrast, a rigorous mathematical model and
This paper introduces a planar tensegrity robot that walks passively and cyclically on a gentle downhill, where its gait versatility can be strengthened by applying actuation forces on the connection cables. The novelty of this work is that we design the structure of this passive robot inspired by t…
Biological observations on tetrapods locomotion deduce that anti-phase synchronization (APS) between fore and rear parts is beneficial for achieving a high-speed walking. On the other hand, theoretical analysis and experimental studies on quadruped robots suggest that a flexible spine potentially im…
This Letter presents a robot walking control method, which we call “quasi-passive dynamic walking.” The method is targeted at underactuated legged robots and applied to obtain energy-efficient limit cycle gait on level ground. To achieve efficient locomotion, as well as to overcome the underactuatio
The authors have investigated underactuated locomotion robots with an inner wobbling mass, it is discovered that the wobbling mass controls the gait speed by entrainment. Supplying the wobbling from outside, outer wobbling entrains load objects and controls the transferring speed. In this paper, we…
After occasional perturbation, it is crucial to spontaneously control the limit cycle walking so that it quickly returns to its closed orbit in phase space. Otherwise, its stability can not be sufficiently guaranteed if the speed of recovery is slow while successive perturbation is applied. The accu…
The author has investigated the method of stealth walking for generating adaptive walking gaits of underactuated walkers without having the control torques at the feet. This approach is also effective for achieving careful walking on the frictionless road surface by applying angular momentum constra…
Towards achieving stable and high performance locomotion on a slippery ground, underactuated sliding locomotion robots have been proposed in our previous studies. Unlike walking robots stepping with legs, this legless robot generates sliding locomotion on a slippery road surface by means of its body
Stealth walking is a way of walking carefully and noiselessly, and is an approach to stable legged locomotion of underactuated robotic walkers on irregular terrains. This paper proposes a method for generating a high-speed stealth walking gait without including double-limb support phase, and discuss…
With the purpose of achieving stable and energy efficient locomotion on the slippery road surface, a sliding locomotion robot without joint torque but indirectly controlled by an active wobbling mass is recently proposed. In this paper, we deepen the analysis of the mechanism of the indirectly contr…
Precisely manipulating the center of mass (CoM) of the underactuated locomotion robot can't be easily achieved by common control mechanisms which apply only joint torques. A novel and indirect method has been recently introduced using an active wobbling mass attached to limit cycle walkers. The next…
Toward stable gait generation on a steep slope, this paper discusses a method for generating a stable walking gait completing in one step for an underactuated rimless wheel. First, we introduce a model of a six-legged rimless wheel with a reaction wheel, and develop two controllers for the single-li…
This paper proposes an approximate-kinetic-model-based self-adaptive (AKS) control system to rapidly generate target walking speed by an underactuated compasslike bipedal walker. First, a model of the underactuated compass-like bipedal walker is built, and an open-loop system is introduced and analy…
This paper discusses the condition necessary for achieving stable sliding passive-dynamic walking of a compass-like biped robot with semicircular feet, and analyzes the fundamental gait properties through numerical simulations. First, we introduce the semicircular-footed compass model and develop th…
This paper discusses a method for generating an underactuated bipedal gait completing in one step in the presence of an upper body that behaves as zero dynamics. First, we introduce a model of a 3-link planar biped robot with an upper body, and develop the equation of motion and holonomic constraint…
The authors demonstrated that a stable passive compass gait can be generated on a slippery downhill, and showed that the 2-DOF constraint conditions for the contact point are not always necessary for it. The generated walking gait while sliding on the slope becomes 3-DOF increased by addition of the
This paper proposes a novel method for generating an underactuated bipedal gait that completes in one step. First, we introduce an underactuated biped robot model that has a circular torso as a reaction wheel. Second, we consider an input-output linearization to formulate an output-following control…
This paper investigates the analytical solution of target steady walking speed in 1-DOF limit cycle walking. We introduce an active combined rimless wheel (CRW) model to analyze the target steady walking state when the CRW walks on level ground. The walking speed is determined by the step period bec…
In this paper, we propose a novel speeding-up method for biped walking using a swinging-arms motion based on the principle of an up-and-down wobbling mass. We have shown that biped robots with a wobbling mass can achieve fast walking using an active up-and-down motion of the wobbling mass. We have a…
In this paper, we discuss the possibility and fundamental properties of passive bipedal walking on a slippery downhill. First, we develop a mathematical model of the passive compass-like biped robot that contacts with the ground incorporating sliding friction which is specified as the Coulomb model.…
This paper proposes a novel underactuated rimless wheel (URW) that has high stiffness and reproduces walking motion sliding on a slippery road surface. First, we describe the overview of the experimental URW we developed and its mechanical features. Second, we develop the equations of motion and col…