This paper presents the design of a reconfigurable manipulator capable of performing Schönflies and Remote Center of Motion (RCM) operations. The Schönflies mode handles plane objects efficiently, like a SCARA robot, while the RCM mode enables the remote center operation, similar to a Da Vinci robot. Through kinematic reconfiguration, the manipulator achieves multimodal operations without component replacement, and the 1R1T module based on a spline lead screw mechanism ensures a compact structure. The kinematic reconfiguration is analyzed in this paper, and mapping rules from joint space to Cartesian space are respectively enabled in different operation modes. The concise kinematic expression without actuation redundancy simplifies control in both modes. Experimental results confirm the manipulator’s versatility in plane object handling and remote center operations, highlighting its effectiveness across diverse applications.

Planetary exploration requires efficient methods for subsurface sampling, especially in extreme energy limitations. Traditional drilling methods are often energy intensive and require large platforms, limiting their applicability. Bio-inspired burrowing techniques, inspired by animals like moles, offer lightweight, low-power alternatives suitable for small robotic platforms. This paper presents a novel bio-inspired robotic platform, the Mole-like Incisor-Burrowing Robotic Platform (MIRP), designed to mimic the incisor-burrowing behavior of naked mole rats. The MIRP features an 11 DOFs mechanism with a compact design (220 mm × 140 mm × 80 mm) and uses servomotors to achieve low energy consumption. The robot combines a qu0adrupedal locomotion mechanism with an incisor-burrowing mechanism, allowing it to navigate granular terrains and perform excavation tasks. Kinematic analysis, including inverse kinematics and close-chain analysis, was conducted to optimize the robot’s motion strategy. A prototype was developed and tested in a simulated lunar regolith environment to test its maneuverability and burrowing performance. The power consumption of the prototype is below 10 W. This work validates the feasibility of bio-inspired incisor-burrowing for planetary exploration, offering a cost-effective and efficient solution for future extraterrestrial missions.

The mobile robots possess immense application potential in planetary exploration, field investigation and other related fields. Adopting suitable movement modes in multiplex task scenarios and flexible modes transformations significantly enhance the flexibility and mobility efficiency of robots. Therefore, a novel multi-modal mobile robot with various ground and aerial movement modes is proposed. Notably, different modes transformation and aerial manipulation can be smoothly performed during aerial maneuvers, thereby improving the deployment efficiency of robots. Firstly, the proposed multi-modal robot achieves high-integration and high-mobility efficiency in all modes through the iterative optimization design. Subsequently, a comprehensive hybrid dynamic model of the robot is established. Based on the dynamic model, the leg motion trajectory during the aerial transformation is planned by optimizing the coupling torque, minimizing the motion's interference on the flight system. Additionally, controllers for various movement modes are designed, including a novel flight controller based on the trajectory linearization control (TLC) method with an extended state observer (ESO), compensating for the time-varying inertial parameters of the robot and coupling or external disturbances, improving the agility and stability of the system in aerial. Finally, the practicability and effectiveness of robot’s multi-modal mobility, modes transformations and aerial manipulation are validated through simulations and real-world experiments.

Knee pain is prevalent in over 20% of the population, limiting the mobility of those affected. In turn, isokinetic dynamometers and robots have been used to facilitate rehabilitation for those still capable of ambulation. However, there are at most only a few wearable robots capable of delivering isokinetic training for bedridden patients. Here, we developed a wearable robot that provides bedside isokinetic training by utilizing a variable stiffness actuator and dynamic energy regeneration. The efficacy of this device was validated in a study involving six subjects with debilitating knee injuries. During two courses of rehabilitation over a total of three weeks, the average peak torque, average torque, and average work produced by their affected knees increased significantly by 81.0%, 101.4%, and 117.6%, respectively. Furthermore, the device's energy regeneration features were found capable of extending its operating time to 198 days under normal usage, representing a 57.8% increase over the same device without regeneration. These results suggest potential methodologies for delivering isokinetic joint rehabilitation to bedridden patients in areas with limited infrastructure.

Roller skating with passive wheels on a quadrupedal robot is more efficient than traditional walking. However, the typical mammalian quadruped robot with 3-DoFs legs can only perform one dynamic roller skating gait and has difficulty achieving turning motion. To address this limitation, we designed a novel quadrupedal robot with each leg having 4-DoFs to enable various roller skating locomotion including Swizzling, Stroking, and trot-like gaits while easily achieving turning motions. We considered the geometrical characteristics of the passive wheel and used the Levenberg-Marquardt method in robot kinematics to improve precision for both roller skating kinematics and contact point position for the dynamics controller. The position of the robot foot and the yaw angle of the passive wheel are decoupled for motion planning of all proposed gaits. Our proposed kinematics with wheeled geometry was verified through experiments to have higher precision, while the feasibility of all proposed roller-skating gaits was confirmed during straight motion and turning motion with a small radius on our prototype robot. Finally, we discussed the mobility efficiency of different roller skating gaits which were found to be more efficient than walking.

The emergence of intelligent prostheses has facilitated the life and work of disabled patients. The interaction aspect of prostheses has become a highlight research topic in the field of rehabilitation robotics. However, most of the existing prosthetic interaction methods focus on the use of myoelectricity to classify finite gestures, rather than continuous (infinite) force detection, which greatly limits the use of prosthetic scenarios. In this study, a novel optical waveguide sensor was used to collect muscle deformation information from the human arm for continuous control of the prosthetic grip force. The optical waveguide sensor was embedded with carbon fiber to limit the stretching of the waveguide, which led to the optical waveguide sensor being sensitive to bending deformation. Compared with EMGs, the accuracy of continuous grip force control based on the optical waveguide sensor is higher. The R-Square for prosthetic grip force and hand grip force were 0.867 and 0.9724 in the periodic and sustaining grip force experiments, respectively. The results suggested that the proposed method could provide a new approach to the interaction of prostheses.

Legged mobile manipulators are receiving much more attention. Mobile platforms can infinitely expand the workspace of robotic arms, providing more possibilities for robot application scenarios. Compared with wheeled mobile manipulators, legged mobile manipulators have higher requirements for cooperative control of legged robots and robotic arms. This work decouples the control of the robotic arm and the legged robot. On the legged robot side, we explicitly estimate the wrench exerted by the robotic arm on the base and bring it into the legged robot’s dynamics, and then use a nonlinear model predictive controller (NMPC) to control the legged robot. On the robotics arm side, we adopt an impedance controller to realize the end-effector’s force control, and the introduction of impedance control has improved the safety and interactivity of legged mobile manipulators. We conducted experiments on physical robot to compare the differences between decoupled control and independent control, and the results show that the stability and robustness of robot systems have improved using decoupled control.

This paper presents a bionic foldable wing that imitates the hind wing of ladybirds. Based on the folding mechanism of the hind wing of ladybirds and the theory of origami, the motion model of the bionic foldable wing is established, yield the motion law of the crease angles and the variation relationship between the panels are obtained. Bionic foldable wings utilise shape memory alloy to drive wings to fold, and embedded torsion springs to release energy to realize the function of wing unfolding. In the experiments of the vehicle equipped with foldable wings, the lift and attitude torque of bionic foldable wings are measured by the F/T sensor. The experimental results indicated that its aerodynamic performance is basically close to that of our optimized non-foldable wings. Moreover, the vehicle with foldable wings has been able to overcome gravity to achieve flight, which provides a novel concept for the research on flapping wing.

This paper presents a novel variable stiffness actuator (VSA) based on a cam-leaf spring mechanism, namely, CLSM-VSA. A sophisticatedly designed cam is used to regulate the transmission ratio between the deformation of the leaf spring and the deflection angle of the VSA, such that the stiffness profile of the actuator can be customized (linear, softening, or hardening). This property is meaningful for specific applications, e.g., VSAs with softening stiffness profiles help reduce the collision force, which is verified by our experiments. Moreover, the stiffness of the proposed actuator can also be continuously regulated by adjusting the location of the pivots that are in contact with the leaf springs. In this case, the stiffness not only can be changed passively with fast speed when the applied torque changes, but can also be regulated actively for different circumstances. Compared to other designs with similar output torque or power, the CLSM-VSA has the merits of compactness, low-power cost stiffness regulation, and high-power density. Additionally, the CLSM-VSA also features wide-range stiffness regulation, and the ratio between the maximum and minimum stiffness is approximately 20. The stiffness characteristics, control performances, and stiffness regulation efficiency of the proposed design are experimentally evaluated.Note to Practitioners—The VSA is a class of compliant actuators that can perform joint positioning and mechanical stiffness regulation, and its inherent compliance makes it suitable for robotics that have physical interaction with environments. In the design of VSAs, compactness and the capability of stiffness regulation are always the most critical features. This paper proposes a novel VSA based on a cam-leaf spring mechanism, which can derive customized stiffness profiles for specific requirements, e.g., softening stiffness for enhancing collision safety. Additionally, we can also actively regulate the actuator stiffness by using a stiffness regulation motor over a wide range and with low-power cost, which makes the actuator suitable for different circumstances. The use of cams and parallelly assembled leaf springs results in a compact design, and the power density ranks high among the designs in the literature. Moreover, the stiffness ranges can be changed by replacing cams, which does not affect the overall dimension of the actuator and benefitsmodularization. In the future, we will focus on the application oftheproposed VSA and further explore the advantages of VSAs with adjustable nonlinear stiffness properties.

Visual SLAM methods based on point features have achieved acceptable results in texture-rich static scenes, but they often suffer from a deficiency of texture and the existence of dynamic objects in real indoor scenes, which limits the application of these methods. In this paper, we have presented DRG-SLAM, which combines line features and plane features into point features to improve the robustness of the system. We tested the proposed algorithm on publicly available datasets, and the results demonstrate that the algorithm has superior accuracy and robustness in indoor dynamic scenes compared with the state-of-the-art methods.

The multiple autonomous underwater vehicle (AUV) formation plays an important role in underwater missions, such as oceanographic sampling and water pollution monitoring. This article presents the mechatronic design, modeling, formation control, and experiments of multiple AUVs. The structure of the AUV and a simplified mathematical model for tracking control are described. To achieve formation control, we formulate a control framework for the multiple AUVs. The upper layer is a formation algorithm based on a novel leader-follower control law. The bottom layer is a dynamic controller based on active disturbance rejection control (ADRC). The formation algorithm is in charge of calculating reference values for the followers to maintain a desired pattern with the leader. The stability and convergence properties of the algorithm have been analyzed using the Lyapunov stability method. Meanwhile, an ADRC approach-based dynamic controller is established to track the reference values. Numerical simulations are carried out to analyze formation control and validate the control framework. The multiple AUVs can switch and maintain the formation between the one-line pattern and the$V$pattern. Finally, extensive formation field experiments involving the one-line pattern and the$V$pattern show the good motion ability of the self-designed AUVs and also verify the feasibility of the proposed control approach. Note to Practitioners—The motivation of the article is to design a practical formation control approach for multiple AUVs and verify the control approach in the field. Although there have been a lot of prior research studies on multiple AUVs, how to design a formation control approach subjected to communication bandwidth constraints and how to develop multiple AUVs and verify the effectiveness of the control method in the field are worthy of intense investigation. Hence, this article builds the mechatronic design and dynamic model of the AUV and proposes a novel leader-follower formation control approach based on the dynamics and kinematic model of AUV. Besides, the stability of formation control for multiple AUVs is proven by the Lyapunov theorem. Multiple AUVs can switch and maintain formation between$V$pattern and one-line pattern with a smaller error. Finally, the performance of the proposed formation control strategy is experimentally verified using three self-made AUVs inside a large reservoir. The proposed method is suitable for multiple AUVs missions involving underwater surveillance, underwater pipeline inspection in the ocean.

With the development of robotics, the underwater robot platform has been widely used in the Internet of Underwater Things (IoUT). An underwater robot platform equipped with multiple sensors is used as a mobile collector to build a reliable information collection system for IoUT. This article presents the mechatronic design, fabrication, modeling, control, simulation, and experiments of a robot IoUT platform to enable the smart ocean. Inspired by the design of both fin-actuated swimming of fish and buoyancy-driven gliding of underwater glider, a novel multilink gliding fish robot is proposed. The multilink gliding fish robot, which is called FishBot in this article, can swim flexibly and glide energy efficiently in three dimensions. In the FishBot, the body and/or caudal fin (BCF) with three degrees of freedom and buoyancy-driven system was equipped as the main propulsion device. Besides, a pair of pectoral fins was equipped to assist in regulating the gliding attitude and enhance the FishBot maneuverability in the vertical plane. The dynamic model that consists of cruise swimming motion, pure-pitching swimming motion, and 3-D swimming motion for control is established. Moreover, a behavioral control framework is developed to achieve a variety of fish-like swimming behaviors and gliding motion. Meanwhile, we proved the stability of the linear quadratic regulation controller and the locomotion controller is provided with exponential stability. The validity of the proposed model and the designed controller is demonstrated by numerical simulations. Finally, a series of experiments involving different fish-like behaviors and gliding motion elucidates the powerful locomotion ability of the FishBot.

In this paper, a multi-propeller multifunction aerial robot (MMAR) capable of flying, wall-climbing and arm-operating is presented. Four propellers are devoted to the attitude control of the robot, and two manipulators are designed for the wall-climbing and arm-operating modes. When the aerial robot works in wall-climbing and arm-operating, there are dynamics coupling between the manipulators and the main body. The dynamics of manipulators depends on the motion of the main body, and the motion of manipulators will have reaction force and torque applied on the main body. The dynamics modeling of the robot is investigated by using recursive method. Based on the model, the trajectory linearization control of the robot is proposed. The controller of the robot when it transitions between its flight mode and wall-climbing mode is then designed. The simulation verification of the controller is presented, which can verified the feasibility of the controller.

In automatic assembly, a vibratory bowl feeder plays a crucial role for reorienting the parts and feeding them into an assembly process. Taking the bowl as a platform and three prismatic flat-spring supports as spatial compliant legs and based on the continuum dynamics, this paper examines the bowl feeder from the point-of-view of a compliant platform device by applying von Mises' compliance study to each of the flat-spring legs and establishes a screw system of each leg. The compliance and Jacobian matrix of the bowl feeder are presented, the potential and kinetic energies are analyzed, and the dynamics models are established, leading to the characteristic equations of the compliant platform device. This generates for the first time the shape function integrated stiffness matrix and inertia matrix. This paper further analyzes the two characteristic equations of both a simplified system and a generalized system, implements the comparative study of the system natural frequencies between the two system models, and presents the stability analysis involving the system hysteresis damping. The effect of platform design parameters on the natural frequencies of the system under damping is identified and modal analysis of the system is carried out according to different forms of the excitation force. This paper presents a comprehensive study of the dynamics of this kind of compliant devices.