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In this paper, a parallel quadrupedal robot was designed that is capable of versatile dynamic locomotion and perception-less terrain adaptation. Firstly, a quadrupedal robot with a symmetric legs and a powerful actuator was implemented for highly dynamic movement. Then, a fast and reliable method based on generalized least square was proposed for estimating the terrain parameters by fusing the body, leg, and contact information. On the basis of virtual model control (VMC) with the quadratic program (QP) method, the optimal foot force for terrain adaptation was achieved. Finally, the results obtained by simulation and indoor and outdoor experiments demonstrate that the robot can achieve a robust and versatile dynamic locomotion on uneven terrain, and the rejection of disturbances is reliable, which proves the effectiveness and robustness of this proposed method.

Aiming at highly dynamic locomotion and impact mitigation, this paper proposes the design and implementation of a symmetric legged robot. Based on the analysis of the three-leg topology in terms of force sensitivity, force production, and impact mitigation, the symmetric leg was designed and equipped with a high torque density actuator, which was assembled by a custom motor and two-stage planetary. Under the kinematic and dynamic constraints of the robot system, a nonlinear optimization for high jumping and impact mitigation is proposed with consideration of the peak impact force at landing. Finally, experiments revealed that the robot achieved a jump height of 1.8 m with a robust landing, and the height was equal to approximately three times the leg length.

The jumping motion of legged robots is an effective way to overcome obstacles in the rugged microgravity planetary exploration environment. At the same time, a quadruped robot with a manipulator can achieve operational tasks during movement, which is more practical. However, the additional manipulator will restrict the jumping ability of the quadruped robot due to the increase in the weight of the system, and more active degrees of freedom will increase the control complexity. To improve the jumping height of a quadruped robot with a manipulator, a bio-inspired take-off maneuver based on the coordination of upper and lower limbs is proposed in this paper. The kinetic energy and potential energy of the system are increased by driving the manipulator-end (ME) to swing upward, and the torso driven by the legs will delay reaching the required peak speed due to the additional load caused by the accelerated ME. When the acceleration of ME is less than zero, it will pull the body upward, which reduces the peak power of the leg joints. Therefore, the jumping ability of the system is improved. To realize continuous and stable jumping, a control framework based on whole-body control was established, in which the quadruped robot with a manipulator was a simplified floating seven-link model, and the hierarchical optimization was used to solve the target joint torques. This method greatly simplifies the dynamic model and is convenient for calculation. Finally, the jumping simulations in different gravity environments and a 15° slope were performed. The jump heights have all been improved after adding the arm swing, which verified the superiority of the bio-inspired take-off maneuver proposed in this paper. Furthermore, the stability of the jumping control method was testified by the continuous and stable jumping.

Wheel-legged robots have the potential of highly dynamic locomotion. The development of Wheel-legged robots might extend the capabilities and provide a solution to the challenges of legged robots. We first modeled our self-developed quadruped experimental platform and expanded our previous work. For the scene of long-range and high-speed movement, we propose a deviation-based online locomotion planner to improve the efficiency and stability of a wheeled quadrupedal robot by reducing unnecessary steps. In the process, relative deviation values are obtained by comparing the ideal foothold reference with the actual wheel position and used to generate locomotion commands. With a control framework of robot locomotion based on a whole-body controller, the robot can move stably for a long distance in the simulation environment. The simulation results also show that compared with the time-based scheduler, this approach has advantages in efficiency and stability.

Legged robots imitating animals have become versatile and applicable in more application scenarios recent years. Most of their functions rely on powerful athletic abilities, which require the robots to have remarkable actuator capacities and controllable dynamic performance. In most experimental demonstrations, continuous hopping at a desired height is a basic required motion for legged robots to verify their athletic ability. However, recent legged robots have limited ability in balance of high torque output and actuator transparency and appropriate structure size at the same time. Therefore, in our research, we developed a parallel robot leg using a brushless direct current motor combined with a harmonic driver, without extra force or torque sensor feedback, which uses virtual model control (VMC) to realize active compliance on the leg, and a whole-leg control system with dynamics modeling and parameter optimization for continuous vertical hopping at a desired height. In our experiments, the robot was able to maintain stability during vertical hopping while following a variable reference height in various ground situations.

For bipedal robots, how to realize natural, versatile and dynamic motions like human is still a challenging topic. In order to achieve such high performance by bipedal robots, one useful approach is to develop joint mechanism with high back-drivability, that makes the dynamic coupling forces such as inertia force, centrifugal force available for dynamic motions and results reduction of necessary capacity for joint actuators leading to the reduction of weight of the robot. For this purpose, in this paper, we propose a novel knee joint mechanism consisting of a crossed four-bar linkage with variable transmission (CFLVT) and a joint stop inspired from human structure. CFLVT behaves as a transmission with variable reduction ratio according the knee joint angle to smooth the static torque so that the knee joint can be driven by a small actuator with low reduction ratio. In addition, a joint stop at the maximum extending angle is introduced in the knee joint which is useful for force assist just like that of a human. The characteristic and design of CFLVT and joint stop are described first. And a prototype of the bipedal robot implemented with CFLVT and joint stop is developed. The feasibility of the proposed mechanism is shown by experimental results for walking and kicking motions.

State estimation is an important part of biped robot control, but unreliable foot contact estimation would lead to inaccurate state estimation result. In this paper, to reduce the state estimation error caused by the inaccurate contact estimation, we propose a novel simplified contact probability estimator based on the force/torque sensor mounted on the foot. The contact probability is used to tune the covariance matrices of the extended Kalman filter, and the parameters of the probability estimator are optimized iteratively through minimizing the error between state estimation result and ground truth measurement. The experimental result on BHR-6P biped robot shows that the proposed method can effectively reduce the state estimation error.

Fluid-filled fiber-reinforced elastomeric enclosures (FREEs) with a circular cross section, inspired by the muscle structure of octopus arms, are a popular choice for actuators because of their high power density and relatively low manufacturing cost. However, the shape, flexibility, and grasping force of FREEs are slightly different from those of real octopus arms. A soft arm with a semicircular cross section has better bending performance than that of FREEs with a circular cross section and can thus more easily achieve flexible grasping. In this paper, to better describe the deformation of soft arm shape in an underwater environment, a model based on a constrained maximization volume is proposed for a semicylindrical soft arm. In particular, the model takes into account the effect of the expansion of the bottom on the semicylindrical soft arm and the proposed analytical model is used to analyze the factors that affect the helix radius of the soft arm, including the helix angles of the fibers, wall thickness, and inner radius of the soft arm. Then a method for fabricating soft arms with a semicircular cross section (length: 700 mm) and a method for extracting the helix radius are also proposed. Finally, a series of driving experiments is performed to measure the accuracy of the model using a hydraulic platform. Experimental results show that the maximum error rate of the helix radius is between 8.99% and 12.29%. The helix radius can be varied from 74.3 mm to 176 mm by changing the parameters of the soft arm.

Biomimetic robots imitating the characteristics of animals are being developed to help humans understand related phenomena in order to engineer new devices. Particularly, soft robotics are being incorporated to help imitating the natural flexibility of animals. Hence, Dielectric-Elastomer Minimum-Energy Structures (DEMES) are used to fabricate soft robots. The advantages of this solution is that the manufacturing procedure is simple. However, high voltages are required for driving them. The challenge is to use this technology at relatively lower voltages. In this research, we aim to realize Soft Underwater robots driven at low voltage to imitate the swimming of Manta. Therefore, we made a DEMES actuator usable in water by sandwiching the carbon as the electrode with two dielectric elastomers. Our robot swims faster at a lower voltage compared to the soft underwater robot that we made in a previous study.

Due to their light weight, flexibility, and low energy consumption, ionic electroactive polymers have become a hotspot for bionic soft robotics and are ideal materials for the preparation of soft actuators. Because the traditional ionic electroactive polymers, such as ionic polymer-metal composites (IPMCs), contain water ions, a soft actuator does not work properly upon the evaporation of water ions. An ionic liquid polymer gel is a new type of ionic electroactive polymer that does not contain water ions, and ionic liquids are more thermally and electrochemically stable than water. These liquids, with a low melting point and a high ionic conductivity, can be used in ionic electroactive polymer soft actuators. An ionic liquid gel (ILG), a new type of soft actuator material, was obtained by mixing 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP) and ZrO2 and then polymerizing this mixture into a gel state under ultraviolet (UV) light irradiation. An ILG soft actuator was designed, the material preparation principle was expounded, and the design method of the soft robot mechanism was discussed. Based on nonlinear finite element theory, the deformation mechanism of the ILG actuator was deeply analyzed and the deformation of the soft robot when grabbing an object was also analyzed. A soft robot was designed with the soft actuator as the basic module. The experimental results show that the ILG soft robot has good driving performance, and the soft robot can grab a 105 mg object at an input voltage of 3.5 V.

In the animal kingdom, many mammals are using their tails to assure their stability while running, jumping, falling, etc. Researches have been performed in order to add tails on wheeled or legged robots in order to improve their stability. However, those tails are often far from the biological structure and resumed to a simple rigid tube with a mass on the extremity. On the other hand the biological tail is composed of many bones moving one on the other and actuated with an important number of muscles. Therefore replicating this structure would result in big and heavy systems using many actuators that would reduce the physical performances of the robot. In this paper, we developed a new bio-inspired cable-driven tail system capable of swinging a flexible tail from base to tip around the pitching axis using a single actuator. First we designed a new flexible tail mimicking the structure of the animal tail. Then we developed a new actuation system using the combination of cams and drive wheels to realize the actuation of 8 cables using a single actuator. Finally, we measured the efforts generated by the swinging motion of the tail and perform experiments to observe its effects on the jumping motion.

The development of a dexterous robotic hand is one of the most important research areas in robotics. In order to grasp a variety of objects, the dexterous robot needs more degrees of freedom, so it requires many motors and complicated structures, which leads to an increase in the weight and size of the dexterous robot hand. This article presents a novel super underactuated robotic hand that uses just one motor and has three cooperative fingers with two phalanxes per finger. The three fingers have the same structure, work in a cooperative mechanism and is driven by the single motor, with a total of 6 degrees of freedom. The grasping principle, process and force analysis are given. Force analysis shows that the super underactuated robot hand is valid and could be used as an end-effecter of humanoid robots. The experiment results verify the stability of the novel mechanism.

In recent years, bio-inspired robots have been researched in order to realize dynamic motions like animals. Focusing on animals' dynamic motions, toes are considered as important mechanisms. In the toes, there are a muscle and tendon that flex the toe joint and extend the ankle joint. The coupled movements between ankle and toe joints can be realized by using the muscle and tendon. The tendon is allowed to store and reuse elastic energy by releasing it during motion. In order to improve the performance of dynamic motion, a toe mechanism inspired by the tendon over the two joints is introduced into our legged robot. In this paper, a toe mechanism with bi-articular tendon consisting of tension spring, cable and pulleys is proposed. Design parameters were determined by simulation, and jumping experiments were carried out using a legged robot with this mechanism. As a result of the experiments, the jumping height of the legged robot with this mechanism has been improved.

In the field of robotics, small cat-like robots, due to its small size, good flexibility, low energy consumption, has become a research trend. Elastic four-bar linkage mechanism (EFLM) with programmable trajectory, good stability, and certain buffer performance, is an excellent choice for driver design of small quadruped robot. We designed a novel miniature cat-like robot, Og-cat, which is optimized in structural features and special parameters compared with other similar quadruped robots. Moreover, we developed a method that can make leg trajectory implement accurately for robots using EFLM. A trajectory realization function is obtained through MATLAB fitting so that the trajectory can be executed precisely. The proposed method has been confirmed on our small quadruped robot Og-cat.

This paper proposes a proximity sensing system, which has advantages of wide sensing area and rapid response. For the rapid and safe behavior of robots, high-speed detection of nearby and noncontact objects is important because of shorter time-to-contact. Here, we propose net-structure proximity sensor (NSPS), which covers large sensing area and fulfills 1-ms response time. NSPS is an array of infrared reflective proximity sensor elements integrated by a resistor network circuitry. Executing analog computation on the electrical circuitry, the sensing system outputs a few of meaningful signals, from the reaction distribution of all the elements. The signals mean the center position and approximate distance to the object. This sensor requires only six external wires regardless of the number of detecting elements. In this paper, we first show that various sizes of NSPS are easily configured by only using standard electronic parts. Next, we prototype NSPS with 25 elements in $5 \times 5$ matrix, and verify the output characteristics by experiments. At last, we discuss the availability of NSPS for robot hand systems and human–machine interface systems.

Hyper dynamic manipulation is defined as highly skilled manipulation with hyper motion specifications, as performed by some athletes. Though hyper dynamic manipulation has been realized in some conventional robots, how to realize hyper dynamic manipulation by a smart structure still remains an interesting and challenging topic to be studied in the robotics field. The purpose of this work is to realize human-inspired hyper dynamic manipulations by a smart manipulator. Based on the analysis results from human hyper dynamic motion, we propose a solution to the realization of hyper dynamic manipulation by robots through utilizing dynamically coupled driving and structural joint stops. This chapter gives the basic idea for utilizing dynamically coupled driving and structural joint 56stops in a hyper dynamic manipulator. The implementation method shows how to realize the manipulation, and the simulations and experimental results provide verification of the overall effectiveness of this proposal.

Compliance control using tactile sensor for robotic hands have been one of the major research topics. Most researchers use a variety of multi-dimensional force sensors with compliance control. In this paper, we replace traditional multidimensional force/torque sensor with one-dimensional pressure sensor. In order to achieve the effect of multi-dimensional sensor, we also propose a vector decomposer to calculate the three-axes position error vector from one-dimensional position signal and make it works in position based impedance control. Finally, the performance of the vector decompose algorithm and compliance grasping are verified in simulation and experiment.

International audience; Mechatronic systems are inherently complex as they are multidisciplinary, integrating both hardware (electronical, mechanical) and software components. A huge effort is needed in the early design stages to take into account the requirements and constraints of the different stakeholders. A system model is needed to facilitate the communication between the collaborators from different domains. These efforts may be considered as a time loss by several companies. However, when a system model is available (i.e. electrical actuator for aircraft industry), it seems obvious that designing a new variant of the system with a modification of a set of requirements requires much less human effort, as it profits from the reuse and change of the already existing models of the previous system. In this paper, we propose to show the usefulness of the capitalization and reuse of system models by showing how a SysML model of an E-Taxiing (Electric Taxiing) aircraft system can be reused in order to design a new innovative HEPS (Hybrid Electric Propulsion System).

We introduce an internet based crossover robot remote control competition project that is an international cooperative program based in Japan, China, Thailand, and Taiwan. This competition is an important component of a long-term higher education reform project aiming to develop a practice based innovative educational methodology jointly promoted by the Ministry of Education, Culture, Sports, Science & Technology of Japan and the University of Electro-Communications. The competition project includes two subjects: the competition itself and the communication and cooperation between students in two countries. The basic mode of the competition is a locally controlled robot and a remotely controlled robot cooperate with each other to complete some tasks. As a unique feature of the project, the student–student communication and cooperation are increased through a specially designed team organization structure that each team consists of two groups from different universities in different countries and the team members are required to cooperate through the internet to complete the competition. The competition has been successfully held four times and the results show it greatly benefits the students, and is expected to promote the development of the practice based educational methodology in the near future.

Some creatures can realize dynamic locomotions with a slender body by utilizing the dynamic effect by moving their whole body besides their legs. For example, some mammals moving by hopping with two legs at high speed and high efficiency have a tail as long as their body length. Their tails are composed of multi-joint and are flexible. The dynamic effect by swinging their flexible tails is useful for fast running and high jumping. In this paper, we develop a flexible tail mechanism for two-legged robot inspired by the flexibility of the animal tail. This tail is comprised of 6 linkages in series and the linkages are connected with elastic passive joints. First, the elasticity of tail joints and the motion of the tail base joint are designed by jumping simulations. To evaluate the effectiveness of the flexible tail mechanism, jumping experiments have been conducted using the prototype of the two-legged robot with the flexible tail as well as rigid tail. The results of these experiments show that the legged robot realized higher jumps with using the effect of swinging its flexible tail.

We report our studies of a new motion planning method for a two-link golf swing robot. We introduce two fundamental properties of manipulator dynamics: the time-reversal symmetry property and the pendulum property. The former is used to reverse the rest-to-point pre-impact swing (backswing and downswing) into a symmetric point-to-rest swing in time, and the latter is used to design a proportional-derivative plus gravity, joint and coupling torque compensation control algorithm to plan the reversed pre-impact swing and the point-to-rest follow-through swing. By using this method, accurate impact position and hitting speed control of the golf swing and low computational cost are achieved. The introduced properties hold true for general multi-revolute-joint planar manipulators and the proposed motion planning algorithm can be implemented on them too.