In-pipe Robot Research Articles

Simulation of locomotion conditions of an enhanced vibration-driven in-pipe robot

Simulation of locomotion conditions of an enhanced vibration-driven in-pipe robot

Soft modular pipe robot inspired by earthworm for adaptive pipeline internal structure

Abstract The inspection, maintenance, and repair of complex pipelines have motivated the development of soft robots with highly flexible and good adaptability. In this study, inspired by the unique locomotion of earthworms, we developed a type of smart material–driven soft modular pipe robot capable of stable manipulation and performing in unstructured pipe environments, which easily assembles into more complex configurations with multiple modules for practical use. Our prototype robot consists of three soft telescopic modules connected in series with flexible bellows and a tail friction mechanism, where the modules adopt a high-energy density shape memory alloy spring as an actuator. Based on analyzing the peristaltic process of the module inside the pipe, it is ensured that the geometric constraint performance of the braided mesh pipe is reasonably matched with the thermomechanical performance of the SMA spring to realize the alternating conversion of anchoring and releasing. By optimizing the overall robotic structure, it is demonstrated that our robot achieves robust crawling in horizontal, vertical, variable-diameter, and curved pipes, wet pipes with the partial presence of water, and pipes with complex cavities through simple open-loop on/off control.

Design of hexapod robot equipped with omnidirectional vision sensor for defect inspection of pipeline’s inner surface

Abstract Defect detection of inner surface of precision pipes is a crucial aspect of ensuring production safety. Currently, pipeline defect detection primarily relies on recording video for manual recognition, with urgent need to improve automation, quantification and accuracy. This paper presents a hexapod in-pipe robot with carrying capacity designed to transport the omnidirectional vision sensor to specified location within unreachable pipelines. The feasibility of the robot’s mechanical design and sensor load-carrying module is analyzed using theory calculations, motion simulations and finite element method. To address the challenges of small pixel ratio and weak background changes in panoramic images, a tiny defect segmentor (TDS) based on ResNet is proposed for detecting tiny defects on the inner surface of pipelines. The hardware and software systems are implemented, and the motion performance of the pipeline robot is validated through experiments. The results demonstrate that the robot achieves stable movement at a speed of over 0.1m/s and can adapt to pipe diameter ranging from of 110 to 130 mm. The novelty of the robot lies in providing stable control of the loaded vision sensor, with control precision of the rotation angle and the displacement recorded at 1.84% and 0.87%, respectively. Furthermore, the proposed method achieves a detection accuracy of 95.67% for tiny defects with a diameter less than 3 mm and provides defect location information. This pipeline robot serves as an essential reference for development of in-pipe 3D vision inspection system.

Exciters of vibrations with two pairs of impacting surfaces

Exciters of vibrations of the type when one vibrating mass performs impacts into two immovable supports, which are located on the opposite sides with respect to the mass, are investigated. Here because of the connection of the vibrating mass with the supports the system may have the point of equilibrium located at equal or different distances from the impacting surfaces. Also, because of the difference of coefficients of restitution of impacts the system may have symmetric or non-symmetric laws of motions of the vibrating mass. Such systems are important in pipe robots and other engineering devices. Typical results of investigation of dynamics of such systems are obtained. The presented results can be used in the process of design of systems with vibrators having two impacting pairs. Investigations are performed by using analytical as well as numerical methods (calculations are performed by C++ Builder Community Edition, Newmark constant average acceleration method is used for numerical integration of equations of motion). The obtained typical graphical relationships show symmetric as well as unsymmetric regimes of motion and enable to perform their comparison. The basic novelty of this paper is the investigation of unsymmetric regimes of motion.

Wheel-legged In-pipe Robot with a Bioinspired Hook and Dry Adhesive Attachment Device

Wheel-legged In-pipe Robot with a Bioinspired Hook and Dry Adhesive Attachment Device

Friction Performance of Rubber Sealing Disc Inside Pipe Robots for the Production of High-Paraffin Oil

The in-pipe robot is the most commonly used technique in offshore pipelines. The use of rubber sealing discs is important for in-pipe robots to ensure that the robots are moved by fluid pressures inside offshore pipelines. This paper focuses on the measuring and modeling of the wax–oil gel-breaking process at the soft frictional area between sealing discs and the pipe wall. In this study, a detailed characterization of the gel-scraping process and in situ probing portable microscopy are performed. Two contributions are made in this study. First, a direct observation of wax–oil deposition breaking is employed to detect the minute changes at the in-pipe robot. Second, we find that a simple function is possible to describe the relationship between the wax contents and dewaxing efficiency, in which the debris material removal ratio (DRR) is discussed. Thus, the gel deposition-breaking phenomena are quite different under the influence of rubber sealing discs. This result is further confirmed by the real contact ratio measurements. It is important to research the sealing disc further and apply it more in the petroleum industry, especially in in-pipe robots for deepwater pipeline systems.

Design and Development of Cam-Operated in-Pipe Robot (CIPR)

Design and Development of Cam-Operated in-Pipe Robot (CIPR)

Development of a Wheel-Type In-Pipe Robot Using Continuously Variable Transmission Mechanisms for Pipeline Inspection.

Pipelines are embedded in industrial sites and residential environments, and maintaining these pipes is crucial to prevent leakage. Given that most pipelines are buried, the development of robots capable of exploring their interiors is essential. In this work, we introduce a novel in-pipe robot utilizing Continuously Variable Transmission (CVT) mechanisms for navigating various pipes, including vertical and curved pipes. The robot comprises one air motor, three CVT mechanisms, and six wheels at the end of six slider-crank mechanisms, including three active and three idler ones. The slider crank and spring mechanism generate a wall press force through the wheel to prevent slipping inside the pipe. This capability allows the robot to climb vertical pipes and adapt to various pipe diameters. Moreover, by combining CVT mechanisms, whose speed ratios between the driver and driven pulleys are passively adjusted by the position of the slider, the robot achieves independent and continuous speed control for each wheel. This enables it to navigate pipes with various geometries, such as straight-curved-straight pipes, using only one motor. Since active control of each wheel is not needed, the complexities of the robot controller can be significantly reduced. To validate the proposed mechanism, MATLAB simulations were conducted, and in-pipe driving experiments were executed. Both simulation and experimental results have shown that the robot can effectively navigate curved pipes with a maximum speed of 17.5 mm/s and a maximum traction force of 56.84 N.

Rigid-flexible coupled origami robots via multimaterial 3D printing

Soft robots have significant advantages in flexibility and adaptability and have potential applications in the field of engineering. Unlike traditional manufacturing methods, three-dimensional (3D) printing provides a fast way to fabricate customized and multi-functional robots. However, the fabrication of soft robots requires multimaterial printers and the high-accuracy multi-step assembly process. Among them, fused deposition modeling (FDM) technology has taken the lead compared to other 3D printing methods due to its ease of use, accuracy, and repeatability. However, the FDM multimaterial printing has not been thoroughly explored. Here, we proposed a rigid and flexible material integrated printing approach based on FDM 3D printing technology and reported a cable-driven flexible pipe robot based on Yoshimura origami crease patterns. The implementations show that the robot can realize four-direction bending effectively by the corresponding drive control, which indicates the feasibility of our design and manufacturing method. The proposed approach paves an effective way to design and fabricate the rigid-flexible robot and other devices in the future.

Development of hybrid locomotive in-pipe robot

Development of hybrid locomotive in-pipe robot

A Piezoelectric In-Pipe Robot Driven by Macrofiber Composite Films: Design, Modeling, and Experimental Verification

A Piezoelectric In-Pipe Robot Driven by Macrofiber Composite Films: Design, Modeling, and Experimental Verification

Results of investigation of improved calculation of viscous friction in the model of a pipe robot

Results of investigation of improved calculation of viscous friction in the model of a pipe robot

Pipeline mapping with crawler-type in-pipe robot feature

Pipeline mapping with crawler-type in-pipe robot feature

Effect of underactuated parallelogram shape-shifting for environmental adaptation movement of a three modular in-pipe robot.

This paper presents an in-pipe robot with three underactuated parallelogram crawler modules, which can automatically shift its body shape when encountering obstacles. The shape-shifting movement is achieved by only a single actuator through a simple differential mechanism by only combining a pair of spur gears. It can lead to downsizing, cost reduction, and simplification of control for adaptation to obstacles. The parallelogram shape does not change the total belt circumference length, thus, a new mechanism to maintain the belt tension is not necessary. Moreover, the proposed crawler can form the anterior-posterior symmetric parallelogram relative to the moving direction, which generates high adaptability in both forward and backward directions. However, whether the locomotion or shape-shifting is driven depends on the gear ratio of the differential mechanism because their movements are only switched mechanically. Therefore, to clarify the requirements of the gear ratio for the passive adaptation, two outputs of each crawler mechanism (torques of the flippers and front pulley) are quasi-statically analyzed, and how the environmental and design parameters influence the robot performance are verified by real experiments. From the experiments, although the robot could not adapt to the stepped pipe in vertical section, it successfully shifted its crawler's shape to parallelogram in horizontal section only with our simulated output ratio.

Development and investigation of the vibration-driven in-pipe robot

Vibratory machines are widely used for monitoring and cleaning various tubes, pipelines, intestines, vessels, etc. The problems of ensuring the prescribed dynamic characteristics of such equipment and simultaneous optimizing the power consumption are currently being solved by numerous researchers. The main purpose of this study is to investigate the locomotion characteristics of the novel vibration-driven design of the pipeline inspecting and cleaning robot actuated by an electromagnetic exciter and equipped with the size-adapting and self-locking mechanisms. The research methodology consists of four main stages: an overview of the enhanced robot design; constructing its dynamic diagram and deriving the differential equations of motion; performing the numerical modeling with the help of the Mathematica software and studying the robot’s kinematic characteristics; conducting virtual experiments by computer simulation of the robot motion in the SolidWorks software. The research results present the time dependencies of the robot’s displacement, speed, and acceleration at different working regimes (excitation forces, disturbing frequencies, etc.). The novelty of the performed investigations consists in substantiating the efficient locomotion conditions of the enhanced vibration-driven in-pipe robot. Further investigations can be focused on developing the full-scale laboratory prototype of the robot and conducting experimental studies. The obtained research results can be interesting for engineers and scientists who deal with similar vibration-driven pipeline robots.

Application of TRIZ Innovation Method to In-Pipe Robot Design

The peristaltic in-pipe robot incorporates multiple actuators, and achieving precise cooperative control among these actuators poses significant complexity. To address these issues, the Theory of Inventive Problem Solving (TRIZ) is applied to identify and resolve physical and technical conflicts in the creative design process of peristaltic in-pipe robots. By highlighting the insights on and technical guidance offered by TRIZ’s inventive principles, this paper examines the method for realizing a single-motor-driven peristaltic in-pipe robot from a transmission perspective. By employing a combination of connecting rods, cam mechanisms, and gear systems, a one-DOF peristaltic in-pipe robot was devised. Subsequently, a prototype was constructed, and successful bidirectional motion tests were conducted within pipes. The findings highlight the efficacy of the TRIZ-based design approach in innovatively designing one-DOF in-pipe robots and the unnecessary employment of complex multi-drive cooperative control in peristaltic in-pipe robots.

Automatic T-Branch Travel of an Articulated Wheeled In-Pipe Inspection Robot Using Joint Angle Response to Environmental Changes

The present paper proposes an automatic T-branch travel method of an articulated wheeled in-pipe inspection robot, AIRo-5.2, using its joint angle response to environmental changes. The robot joints are composed of two passive elastic joints with torsional springs and a single active joint using a polyurethane-based series elastic actuator (SEA). By switching from torque control to angle control of this SEA, the AIRo-5.2 can pass through vertical T-branches. However, the timing needed to switch them has not yet been defined, and thus it was necessary to train the operators. Therefore, a method that uses the middle joint angle change was proposed for automatic T-branch travel. To elucidate the phenomenon of this angle change and to determine the effects of a robot's mechanical parameters, a partial dynamic model was constructed when only the head link contact was released at a T-branch. Finally, the travel performance of our developed in-pipe robot was tested on 10 types of T-branches with different gravity directions. From the experiments, although the probability of completing the course was not 100% in all cases, the effectiveness of our proposed principle and algorithm for automatic T-branch travel was confirmed.

Omnidirectional water wave-driven triboelectric net-zero power smart ocean network: An advanced hardware solution to long-distance target detection

Collecting ocean energy to build a zero-power smart ocean network that integrates energy harvesting and application is of great significance for achieving the strategy of marine power. This demands a hardware solution with simple structure, high energy efficiency, and high resolving ability. Herein, we proposed a simple fully symmetric triboelectric nanogenerator (FS-TENG) for efficient collection of omnidirectional wave energy without dead spot, based on the 360 degrees of freedom of inertial ball and the simplified double-layer electrode structure responding to arbitrary triggers. Employing the Maxwell’s displacement current generated by FS-TENG, power-free underwater wireless detection was achieved to sense the long-distance (220 m) target in water, which set a new record for triboelectric nanogenerator (TENG) based contactless sensing. The detection strategy is an effective method for marine data acquisition to realize intelligent ocean management demonstrating applications such as noninvasive inspection of pipeline difficult to reach for in-pipe robot, navigation and berthing for ship in need according its dimension, and sensing water level changes without moving part. The work builds a net-zero power smart ocean network based on TENG, providing new ideas for sustainable ocean development.

A Novel Worm-like In-Pipe Robot with the Rigid and Soft Structure

A Novel Worm-like In-Pipe Robot with the Rigid and Soft Structure

INVESTIGATION OF DYNAMICS OF A PIPE ROBOT WITH SELF-STOPPING MECHANISM

Pipe robots are used in agricultural engineering for transportation of various materials inside the pipe as well as for cleaning of internal surfaces of the pipes.
 In this paper a model of a pipe robot with self-stopping mechanism is proposed and described in detail. Numerical investigations are performed, and the obtained results are presented in the form of graphical relationships. Variations of displacements as well as variations of velocities of the exciting mass and of the case of the pipe robot as functions of time are investigated. Results for steady state regime of motion are presented.
 Displacement of the first degree of freedom, velocity of the first degree of freedom, displacement of the second degree of freedom, velocity of the second degree of freedom as functions of time in the steady state regime of motion are investigated. Also, difference of displacements as well as difference of velocities as functions of time in the steady state regime of motion are represented.
 Results for three typical values of the constant force are described in the paper: first the results when the constant force is assumed equal to zero are presented and then the results for the two typical nonzero values of the constant force are presented. From the obtained graphical representations, the influence of the value of the constant force to the dynamic behavior of the pipe robot can be seen.
 The obtained graphical representations enable to understand the behavior of the investigated pipe robot with self-stopping mechanism.
 Keywords: pipe robot, self-stopping mechanism, harmonic excitation, steady state motions, parameters of the system.