This article presents the design and testing of a novel passive polishing end-effector with adjustable constant force and wide operating angle, which enables adjusting the polishing effect and maintaining the constant contact force for polishing surfaces of large curvature. The constant-force mechanism is obtained by composing a positive-stiffness mechanism and a negative-stiffness mechanism. The magnitude of the constant force can be regulated by adjusting the preloading displacement of the positive-stiffness mechanism. The constant force is provided at a wide tilted angle of the end-effector because the connected counterweight compensates for the gravity effect. The working principle and mechanism design of the proposed polishing end-effector are presented. Based on finite-element analysis simulation, an optimization study is carried out to determine the structural parameters of the constant-force mechanism with expected performances. A prototype of a polishing end-effector is fabricated for experimental tests to evaluate its performance and verify the proposed concept design. The results indicate that the reported polishing end-effector exhibits adjustable constant force and wide operating angle for practical applications.

Cleaning high-altitude building windows is traditionally a high-risk task for human workers due to the danger of falls. To enhance safety in facade cleaning and similar tasks, the development of window-cleaning robots has become increasingly essential. However, current robots face challenges in navigating exoskeleton structures due to obstructive beams, limiting their application. This article proposes a novel biped window-cleaning robotic system (BWCRS) designed for exoskeleton structures. The system comprises two key components: a multifunctional biped climbing robot (BCR) and a specialized cleaning robot. The BCR is adept at overcoming obstacles inherent in exoskeleton structures and transitioning across various inclined window surfaces. The BCR adopts a symmetrical construction, and the ends of the feet are equipped with vacuum suction cups and electromagnets, which can switch between different actuators at the geometric base and end of the system. The system is further enhanced by air pressure sensors that monitor the suction cup adhesion in real time, ensuring stable operation. A crucial functionality of the BCR is its manipulation mode, guided by a visual camera. This mode enables precise location and manipulation of the cleaning robot, ensuring effective coverage of all window areas. The mechanical design and mathematical modeling of the BWCRS are thoroughly examined, demonstrating its robust window-cleaning capabilities. The experimental results reveal that the proposed BCR has a favorable window-climbing and manipulation ability and that the BWCRS has a favorable cleaning effect on the exoskeleton-structure windows. Note to Practitioners —This paper is motivated by the problem of window-cleaning for exoskeleton structures, but it also applies to solving window maintenance and inspection. Previous window-cleaning robots were mainly aimed at the facades or surfaces with low obstacles that cannot be applied directly to exoskeleton-structured windows. This paper proposes an exoskeleton-structure window-cleaning method based on a biped window-climbing robot and a cleaning robot. The biped robot can climb over obstacles on the exoskeleton structures and manipulate the cleaning robot to different cleaning areas. Here, we introduce the biped window-climbing robot from the perspective of mechanical design and mathematical kinematics. We then demonstrate multiple obstacle-crossing motion modes of the biped window-climbing robot. Combined with visual-based manipulation, the window-cleaning process for the exoskeleton structures by a biped window-climbing robot integrated with a cleaning robot is demonstrated. The results verify that the proposed design can complete window-cleaning tasks on exoskeleton structures.

As diverse robotic hands keep emerging for industrial and household use, designing general grasp synthesis algorithms applicable to multiple grippers remains challenging. To improve the generality and effectiveness of multi-gripper planar grasping algorithms, we propose a grasping framework featuring gripper-agnostic scene inference and gripper-changeable optimization. In our approach, we introduce an interaction probability map that bridges the scene inference and grasp optimization modules. It efficiently decouples the learning of grasping knowledge and modeling of gripper's kinematics. The inference module adopts a modified directional ensemble method with a generated fingertip dataset to refine scene information. In grasp optimization, we formulate gripper-kinematic constraints for different grippers according to joint types. Extensive evaluations on the Cornell Grasping Dataset (with a success rate of 95.51%) and on multi-fingered grippers (ten grippers in the real world) demonstrate that our hybrid approach generalizes learnable knowledge across various grippers. This work enables the direct transfer of learned grasping knowledge to new grippers in real-world applications. The open-source project is available at: https://github.com/wangzivector/HybridGen

In modern medical treatment, ultrasound scanning provides a radiation-free medical imaging method for the diagnosis of soft tissues via skin contact. However, the exerted contact force heavily relies on the skill and experience of the operator, which poses great inspection instability. This article reports on a robotic ultrasound scanning system with a constant-force end-effector. Its uniqueness is the introduction of a hybrid active–passive force control approach to maintaining a constant contact force between the ultrasound probe and the continually changing surface. In particular, the passive constant-force mechanism provides strong buffering to the force variation. The active force control system improves flexibility and provides long-stroke positioning. Experimental tests on both silicone models and human volunteers demonstrate the capability of the proposed robotic ultrasound scanning system for obtaining qualified ultrasound images with high repeatability. Moreover, the ease of operation of the robotic US scanning system is verified. This work provides a promising method to assist doctors in conducting better and cushier ultrasound scanning imaging.

In recent years, the rising incidence of gastrointestinal (GI) cancer has triggered an urgent need for effective early intervention strategies. Traditional endoscopic techniques often cause patient discomfort, and it is difficult to navigate deep regions of complex organ structures. This work proposes a kind of bio-inspired magnetic soft robot (BMSR) to address these challenges. The design of the BMSRs is inspired by the rolling motion of the golden wheel spider. Two six-degree-of-freedom (6-DOF) robotic arms are used, where one arm is responsible for real-time manipulation of the BMSRs, and the other is dedicated to monitoring their status. Under the actuation of an external rotating magnetic field, the BMSRs can flexibly climb on inclined surfaces at any angle, involving the inverted surface. Through the powerful output force, the BMSRs can overcome the mobility barrier induced by different human organs, including mucus, folds, and height differences of up to 8 cm. Such an exceptional mobility enables the BMSRs to deliver drugs in the targeted complex GI environment. Moreover, in combination with an endoscope, it provides real-time visual feedback for precise navigation. In vitro animal experiments validate the feasibility of BMSRs, paving a way for their usage in minimally invasive GI treatment. This work advances the potential applications of magnetic soft robots in the biomedical field.

This paper presents the design and development of a novel bioinspired rigid-soft hybrid robotic gripper with versatile grasping primitives and enhanced robustness. It achieves variable joint/tissue stiffness by resorting to hybrid ratchet joints and phalanges. For the first time, the proposed hybrid ratchet joint (HRJ) can selectively switch to four modes to generate tunable flexion/extension locking torque by activating specific clutching ratchets with soft-cell structures. The multi-layer hybrid phalanx can exert suction-lift grasp and adjustable contact stiffness, which are theoretically modeled and experimentally validated by mounting them on articulated fingers. With the proposed HRJs and hybrid phalanges, a tendon-based hybrid gripper is designed and fabricated to evaluate the grasping performance for universal picking and manipulation. Extensive grasping tests are conducted in six representative primitives (including suction-lift and suction-pinch), demonstrating the multi-mode grasping capability in extremely thin and wide objects. Compared with conventional gripper configurations, the proposed hybrid phalanges and HRJs improve the grasping force and enveloping stiffness by 205.1% and 97.9%, respectively. Note to Practitioners —For automated grasping of diverse objects, a bioinspired robotic gripper is proposed to enable adjustable compliant stiffness and suction-lift motion. With the same mobility as conventional tendon grippers, the reported hybrid gripper exhibits wide-range adjustable stiffness and demonstrates versatile adhesive primitives and enhanced robustness in grasping tasks. Experimental investigation is conducted to verify the tissue suction effect and stiffness modulation, demonstrating their contributions to grasping operations in terms of suction-augmented primitives and improved grasping stability. With the characteristics of HRJs and hybrid phalanges, the gripper actuation strategies are elaborated via six representative primitives, including parallel grasp, suction-lift, and newly defined suck-pinch. Extensive grasping trials are demonstrated to pick thin, large, and tiny objects (e.g., wide plates, toolboxes, and tweezers). The experimental results validate the feasibility and superiority of the proposed hybrid gripper design by fusing intrinsic dexterity, manipulability, and compliance from rigid and soft mechanisms.