Guofang Gong

The primary task of precise robot control is achieving shape perception. However, the nonlinear deformation and infinite degrees of freedom characteristics of soft robots make shape perception particularly challenging. Existing shape perception methods often suffer from strong dependencies on environmental conditions and motion constraints. This article reports a shape perception solution based on capacitance sensors, enabling three-dimensional shape reconstruction of a soft bellow robot. The proposed capacitive sensors adopt a nonparallel plate configuration with air as the dielectric and a wedge-shaped air gap between electrodes, whose geometry varies with robot deformation. The sensors are fabricated through a simple casting process, in which cured silver nanowire-based electrodes are embedded into polydimethylsiloxane substrates. For shape perception, multiple capacitive sensors are circumferentially distributed on the bellow surface to capture deformation-induced local inclination and reconstruct the global three-dimensional shape. Experimental results demonstrate that the nonparallel plate capacitance sensor exhibits low hysteresis ( $\boldsymbol{\gamma}$ _H $\boldsymbol{\approx}$ 1.70%), high resolution (0.25 ${}^{\boldsymbol{\circ}}$ ), and a fast response (218 ms). These attributes enable the sensor to perform precise and rapid shape perception under strict experimental environments. Furthermore, the combination of distributed multi-location capacitance measurements and a deep learning network successfully captures the posture information of the bellow, resulting in millimeter-level global shape reconstruction (with an average error of 2.547 $\boldsymbol{\pm}$ 1.230 mm on a 124 mm bellow robot). This drive–perception integrated system provides accurate shape information for soft robots operating in highly constrained environments, such as those encountered in endoscopic and minimally invasive medical procedures.

A thorough understanding of the effects induced by continuous curved pipe jacking on adjacent underground facilities is paramount for ensuring both safety and operational efficiency during construction. This study posits a three-stage analytical framework designed to calculate the displacement of existing objects resulting from sequential vertical curved rectangular pipe jacking. The methodology involves the following stages: first, the stresses at the object surface must be derived based on classical Mindlin’s solutions; second, the displacements at arbitrary points of the object must be determined using the Winkler foundation model, wherein soil–object interactions are modeled as elastic springs to transform displacements into normal and shear forces; and third, the rigid-body displacement and rotation of objects, caused by aggregate forces, must be calculated by kinematic analysis. The validity of the proposed method is confirmed through comparison with a reduced-scale experimental test, and a parametric study discussing the influence of key factors, including Poisson’s ratio and object geometry, is presented.

X-scale manipulation robots, ranging from nanometers to millimeters, primarily rely on hybrid electromagnetic and piezo drives, as standalone piezo X-scale drives struggle with low durability caused by friction-induced wear. Enhancing their lifespan is key to simplifying X-scale manipulation systems and advancing the industrialization of robotic micromanipulation. This article introduces a XScaleBot, a palm-sized, piezo-driven modular serial robot designed for microscale operations within a thousand-cubic-centimeter workspace. The XScaleBot’s joints integrate the advantages of piezo inertial drives and friction self-adaptation after wear. These innovations enable continuous operation around the clock with a resolution of 0.27 μrad, achieving 5.7 pick-and-place cycles per second for micrometer-scale objects. Moreover, the robot’s modular design is compact, allowing for flexible assembly degrees of freedom (DOFs) and interchangeable end effectors. We demonstrate its versatility by completing tasks such as microgear assembly, eye surgery, and integrated circuit testing, using tools like a gripper, syringe needle, and tungsten carbide probe. Our results indicate that the XScaleBot’s rotation joint, when using chrome plates, can support up to 354 km. If ZrO₂ is used instead, the expected lifetime could reach 54 162 km, far exceeding the 2 km lifespan reported for similar existing products.

Soft actuators are increasingly valued for their adaptability to unknown environments and their inherent safety in human–robot interactions. As the scope of soft actuators broadens, there is an increasing demand for actuators capable of handling bidirectional pressure regulation. Existing solutions often face limitations such as high cost, complex control, and large size. Addressing these challenges, this study introduces a compact bidirectional pressure proportional valve (BPPV), measuring only 20 mm × 20 mm × 41 mm. The dual-plunger structure can reduce the cost of BPPV and simplify the control algorithm. The controllable pressure range is −31 kPa to 72 kPa. The maximum temperature increase observed under natural convection conditions was 17.5 $^{\circ }$C. Experimental results demonstrate the BPPV’s ability to precisely regulate bidirectional pressure, making it ideal for tasks such as gripping objects of various sizes and managing soft and fragile items. The BPPV’s compact design, low cost, simple control, stable continuous operation, and suitable pressure range make it particularly well suited for integration into soft robotic systems.

In minimally invasive surgery, pneumatic soft actuators have gained significant attention due to their promising applications. Valves, which are critical components in pneumatic driving systems, typically operate in only two modes in current research. In multi-actuator systems, this limitation results in a large number of valves and a bulky driving system, which restricts the system’s portability. In this study, we report a four-mode, multi-stable, energy-efficient electromagnetic mini valve. A coil serves as the driving source. The valve has three outlets, enabling it to control up to three actuators independently. The moving components include a cylindrical magnet and a ring magnet. They are concentrically arranged and can only move along the axial direction. These magnets can realize four distinct positions based on the electromagnetic force and their mutual magnetic force. Moreover, the multi-stable design reduces energy consumption. The two cores make the magnets stable when no current is applied. The valve exhibits a shortest response time of 4.75 ms and an energy cost of 0.007 J. It can handle a maximum flow rate of 9.7 L/min at a pressure of 200 kPa, with a maximum back pressure of 100 kPa. Its energy-efficient and four-operating-mode characteristics prove its potential in pneumatic soft actuator systems. A modular design by connecting multiple mini valves reduces the number of pumps and valves, thereby lowering the overall size and weight of pneumatic driving systems. Note to Practitioners—Pneumatic soft actuators are widely used in automation systems because they are flexible and safe. However, controlling multiple actuators often needs many valves, making the system large and heavy. This work introduces a small valve with four operating modes. It can control up to three actuators by itself. The valve holds its position without continuous power, which saves energy. It also responds quickly and can deliver a high airflow. By connecting several of these valves, users can build simpler and lighter pneumatic systems. This valve is useful for portable automation devices, medical robots, and wearable systems. In the future, the valve design could be connected to smart controllers for more advanced automatic control.

The thrust system, an important subsystem of a tunnel boring machine (TBM), primarily provides thrust force and adjusts TBM’s attitude in real time. In the tunneling process, only controlling the thrust speed causes pressure oscillations, increases soil deformation, and leads to surface subsidence or upheaval. Conversely, solely relying on pressure control causes fluctuations in speed, making it difficult to ensure that the deviation between the designed tunneling axis (DTA) and the actual tunneling axis (ATA) remains within the permissible range. Due to the increase in geological complexity and higher construction quality standards, primarily relying on single-mode speed or pressure control has become inadequate to meet operational demands. Therefore, to realize higher safety and precise trajectory tracking, it is necessary to ensure speed and pressure compound control for thrust systems. This paper proposes a novel adaptive sliding mode control (ASMC) strategy for thrust systems, which is composed of a proportional pressure relief valve (PPRV) and a proportional flow control valve (PFCV). Firstly, PPRV and PFCV are modeled as a second-order system and an ASMC is employed to control the pressure and speed. Next, to assess the performance of the ASMC controller, simulation experiments were conducted under various conditions, including speed regulation, sudden changed load, and disturbed load. The simulation results indicate that compared to the Proportion–Integral–Differential (PID) controller, the ASMC controller shows almost no overshoot in speed and pressure control during the initial stages, with the response time reduced by approximately 70%. During speed regulation process and sudden changed load process, the response time for both speed and pressure control is shortened by about 80%. In the disturbed load process, the ASMC controller maintains pressure stability. In conclusion, the ASMC controller significantly improves the response speed and stability of the thrust system, exhibiting better control performance under various operating conditions.

Piezoelectric inertial actuators (PIAs) enable cross-scale motion ranging from nanometers to millimeters with simple and compact structures. However, friction and wear issues limit their service life and reliability. This work proposes a cascaded magnet piezoelectric inertial actuator (CM-PIA) for durable service via a wear-adaptive mechanism. Additionally, the displacement vibration characteristic in PIAs, typically considered a defect, has been positively utilized for the first time. Through friction experiments, we demonstrated the CM-PIA's advantages in wear adaptability, modular interchangeability, and assembly adaptiveness. The actuator operated over 190 km with 2.5 μm wear and showed a 16% frictional force reduction with 4 mm wear, theoretically enabling operation for 300 000 km and enhancing the travel life by three orders of magnitude. The replacement cost for the modular magnetic actuated foot is only 4 cents, and it exhibits stable friction over an extended stroke of 400 mm. Employing three degrees of freedom (DOF) integration, we have applied the CM-PIA, which possesses a stroke up to 18 mm and a test resolution was 4 nm, in minimally invasive cellular manipulation utilizing displacement vibration by a singular core for the first time.

Segment assembly is one of the principal processes during tunnel construction using a tunnel boring machine (TBM). The segment erector is a robotic manipulator powered by a hydraulic system that assembles prefabricated concrete segments onto the excavated tunnel surface. In the case of a larger diameter, while the segment assembly has a more extensive range of motion, it also demands more control accuracy. However, the single-pump-based hydraulic system fails to meet the dual requirements. Therefore, this paper proposes a novel dual parallel-connected-pump hydraulic system consisting of a small displacement pump and a large displacement pump. On this basis, taking advantage of both the quick response and low dead zone of the small pump and the high flow range of the large pump, a two-level error allocation strategy is constructed to coordinate the two pumps and keep the motion error of segment assembly within a small range. Finally, comparative experiments were conducted, and the results show that the proposed scheme achieves the simultaneous high-level synchronization of the two pumps and high-precision and high-speed motion-tracking performance.

The rapid and accurate control of air chamber pressure in slurry pressure balance (SPB) shield tunneling machines is crucial for establishing the balance between slurry pressure and soil and water pressure, ensuring the stability of the support face. A novel air chamber pressure control method based on nonlinear adaptive robust control (ARC) and using a pneumatic proportional three-way pressure-reducing valve is proposed in this paper. Firstly, an electric proportional control system for the air chamber pressure is developed. Secondly, a nonlinear state space model for the air chamber pressure regulation process is established. Utilizing experimental data from the SPB shield tunneling machine test bench, nonlinear adaptive identification is conducted through the nonlinear recursive least square algorithm. The results demonstrate the model’s effectiveness and accuracy. Then, a nonlinear ARC for air chamber pressure is designed based on the backstepping method, and its Lyapunov stability is proved. Finally, the feasibility and effectiveness of the controller designed in this paper is verified through simulation and experiments. The results demonstrate that the developed control system can compensate for the nonlinearity and disturbance in the air chamber pressure regulation process. It can achieve good transient and steady-state performance and has good robustness against uncertainty.

Advances in intelligent shield machines reflect an evolving trend from traditional tunnel boring machines (TBMs) to tunnel boring robots (TBRs). This shift