A variable magnification ratio transmission structure powered by the electric actuators is proposed to improve the flexibility and portability of the exoskeleton under heavy load carrying condition. The parameters of connecting rod size and hanging position are optimized to ensure that the output torque of active joints can fully envelope the demand load area. The control strategy based on intrinsic sensing is designed to realize the automatic human motion intention prediction and flexible trajectory tracking. The newly developed split embedded connecting rod can accurately measure the human-robot interaction (HRI) force applied to the exoskeleton and extract the human motion intention without being affected by the differences in wearing status. The force tracking control based on the zero-force following is modified by feedforward compensation with extreme learning machine (ELM), which enhances the response speed to human motion intention and reduces the HRI force by 70.6%. Based on multi-sensor information, stacked autoencoder deep neural networks (DNNs) are utilized to realize the automatic locomotion transition and the corresponding control parameters' switching. After optimization by a hybrid algorithm of genetic algorithm and particle swarm optimization (GA_PSO), the identification accuracy is enhanced from 96.2% to 99.7%. The adaptive neural-fuzzy inference system (ANFIS) is used to analyze the plantar pressure to achieve flexible switching between the swing phase and the stance phase. The experiments under various gait motion trajectories assisted by novel weight-bearing exoskeleton are carried out for evaluation, and the performance of the proposed control strategy based on motion intention prediction, locomotion mode identification, and gait phase switching is effectively verified.

AimTo evaluate the effect of bone morphogenetic protein 2 (BMP‐2) incorporated biomimetic calcium phosphate (BMP‐2/BioCaP) in conjunction with barrier membrane on periodontal regeneration in chronic periodontitis experimental model.Material and MethodsChronic periodontitis experimental model with critical‐sized supra‐alveolar defects was created in 15 dogs’ mandibles. After the initial periodontal therapy, the defects were randomly assigned to the following groups: (a) control; (b) barrier membrane; (c) deproteinized bovine bone mineral + barrier membrane; (d) BioCaP + barrier membrane and (e) BMP‐2/BioCaP + barrier membrane (6 quadrants with 18 teeth per group). Eight weeks later, clinical examinations, micro‐CT, and histomorphometric analyses were performed.ResultsClinical examinations, including plaque index, bleeding index, and probing depth, were similar for all groups. In contrast, the clinical attachment loss was significantly lower in defects grafted with BMP‐2/BioCaP and barrier membrane. The micro‐CT results showed that the height of mineralized tissue in defects grafted with BMP‐2/BioCaP and barrier membrane was significantly higher. For histometric analysis, the defects grafted with BMP‐2/BioCaP and barrier membrane exhibited significantly more connective tissue height, new cementum height, new bone height and area, as well as less down‐growth of junctional epithelium.ConclusionBMP‐2/BioCaP could be a promising bone substitute for periodontal regeneration.

The highly agile and efficient water-surface locomotion of the water strider has stimulated substantial interest in biomimetic research. In this paper, we propose a new miniature surface tension-driven robot inspired by the water strider. A key feature of this robot is that its actuating leg possesses an ellipse-like spatial trajectory similar to that of a water strider by using a cam-link mechanism. Simplified models are presented to discuss the leg-water interactions as well as critical conditions for a leg penetrating the water surface, and simulations are performed on the robot's dynamic properties. The final fabricated robot weighs about 3.9 g, and can freely and stably walk on water at different gaits. The maximum forward and turning speeds of the robot are measured as 16 cm s −1 and 23°/s, respectively. Furthermore, a similarity analysis with Bond number and Weber number demonstrates that the locomotion of this robot is quite analogous to that of a real water strider: the surface tension force dominates the lifting force and plays a major role in the propulsion force. This miniature surface tension-driven robot might have potential applications in many areas such as water quality monitoring and aquatic search and rescue.

The highly efficient and agile water-surface locomotion of water striders has attracted substantial research attention. Compared with imitating the horizontal rowing motion, imitating the jumping capability of water striders is much more challenging because the strong interaction in the jumping process easily causes the robot to sink. This study focuses on designing a miniature robot capable of continuously jumping on the water surface. A spring-based actuating mechanism is proposed to produce a large jumping force. The center of gravity of the robot is carefully designed to allow the robot to jump on the surface continuously and smoothly. The influences of several critical factors, including the area of the supporting legs, the spring stiffness, the jumping angle, etc on jumping ability are analyzed by means of dynamic simulation and experiments. The jumping performance under different jumping angles is tested. The fabricated robot weighs approximately 10.2 g and can continuously jump on water with a maximum leap height and length of 120 and 410 mm, respectively. This study helps researchers understand the jumping mechanism of water striders and provides a reference for developing water-jumping robots that can perform various aquatic tasks in the future.

Hemiplegia, apoplexia, or traffic accidents often lead to unilateral lower limb movement disorders. Traditional lower limb rehabilitation equipments usually execute walk training based on fixed gait trajectory; however, this type is unsuitable for unilateral lower limb disorders because they still have athletic ability and initiative walking intention on the healthy side. This article describes a wearable lower limb rehabilitation exoskeleton with a walk-assisting platform for safety and antigravity support. The exoskeleton detects and tracks the motion of the healthy leg, which is then used as the control input of the dyskinetic leg with half a gate-cycle delay. The patient can undergo walk training on his own intention, including individual walking habit, stride length, and stride frequency, which likely contribute to the training initiative. The series elastic actuator is chosen for the exoskeleton because the torque output can be accurately detected and used to calculate the assisted torque on the dyskinetic leg. This parameter corresponds to the recovery level of a patient's muscle force. Finally, the walk-assisting experiments reveal that the rehabilitation exoskeleton in this article can provide the necessary assisting torques on the dyskinetic leg, which can be accurately monitored in real time to evaluate a patient's rehabilitation status.

The agile and efficient locomotion of water striders on water surface is attributed to the water repellency ability of their slender legs. The legs are usually treated as rigid beams, neglecting the effect of flexible deformation on its movement. Several studies proved that the stable floating ability of water striders is closely related to the flexible legs. This paper focuses on exploring the flexible driven mechanism between the insect and the surface of water and applied them to design a robot. The spatial deformation and force models of the driving legs are established and analyzed based on the Euler-Bernoulli's beam theory. The influence of flexural rigidity and depth of a driving leg on the rowing speed is studied. Results indicates that a flexible driving leg can effectively increase its critical rowing speed and ensure that it does not penetrate the water surface at a higher speed, thus achieving a bigger driving force. Then a water strider robot capable of walking on water surface is proposed, which possesses ellipse-like spatial trajectories by using a limit pinlinkage. The driving legs are fabricated by different stiffness materials. Finally, the skating experiments of the robots with different stiffness of the driving legs were carried out. The results verified that the maximum rowing frequency of the flexible driving legs and maximum moving speed of the robot are more than 30% higher than those with rigid legs, respectively. Moreover, a similarity analysis of hydrodynamic characteristic constants reveals that the flexible driving robot is more analogous to the biological water striders. INDEX TERMS Flexible driving legs, miniature robot, surface tension, water strider.

Abstract. This paper introduces novel modern equipment-a lower extremity exoskeleton, which can implement the mutual complement and the interaction between human intelligence and the robot's mechanical strength. In order to provide a reference for the exoskeleton structure and the drive unit, the human biomechanics were modeled and analyzed by LifeModeler and Adams software to derive each joint kinematic parameter. The control was designed to implement the zero-force interaction between human and exoskeleton. Furthermore, simulations were performed to verify the control and assist effect. In conclusion, the system scheme of lower extremity exoskeleton is demonstrated to be feasible.

PurposeThe purpose of this paper is to present a new scout robot that tries to combine the hopping movement and the wheeling movement to greatly enlarge the scope of robot's activities.Design/methodology/approachA five‐shank hopping mechanism was employed to build the wheeling‐hopping combination scout robot. The non‐linear character of the five‐shank hopping mechanism was analyzed and then used in the proposed non‐linear spring‐mass model for the robot.FindingsThe rules of robot's movement were deduced, influencing factors of the jumping height were analyzed and the countermeasure was adopted. Simulations and an experiment of the robot's movement showed that the robot has strong locomotivity and survival ability.Originality/valueA five‐shank hopping mechanism is proposed, analyzed and combined with wheeling movement to enhance the locomotivity and survival ability of scout robot.