Robotic Mechanisms Research Articles

Rigid-hyperelastic Coupling Dynamic Model and Dynamic Characteristics of Spring type of Traction Robot

The traditional anchoring mechanism of the traction robot is rigid, which is easy to be stuck in the wellbore. In order to solve the problem produced by the rigid anchoring mechanism of the traction robot, a novel anchoring mechanism was proposed based on the spring type of anchoring mechanism of the inclined block. The key to make the traction robot motion is whether the traction robot can be anchored on the wellbore under the action of the traction force. Therefore, a rigid-hyperelastic coupling dynamic model of the spring type of anchoring mechanism under the action of the traction force was established. On the basis, the effects of span, width, thickness and chamfer parameters on the anchoring performance of the spring type of traction robot were analyzed. Through the experimental comparison, it was found that the error between the theoretical supporting force and the experimental supporting force is only 6.1%, and the maximum error of theoretical and experimental maximum traction force is 4.9%. Experiments verified the correctness of the rigid-hyperelastic coupling dynamic model. The research results of this paper lay a foundation for the structural design and engineering application of spring type of traction robot. It can effectively ensure the downhole safety of oil and gas wells.

Motion analysis and stability optimization for metamorphic robot reconfiguration

AbstractMetamorphic robots are a new type of unmanned vehicle that can reconfigure and morph between a car mode and a biped walking machine mode. Such a vehicle is superior in trafficability because it can drive at high speeds on its wheels on structured pavement and walk on its legs on unstructured pavement. An engineering prototype of a metamorphic robot was proposed and designed based on the characteristics of wheeled–legged hybrid motion, and reconfiguration planning of the robot was conducted. A kinematics model of the reconfiguration process was established using the screw theory for metamorphic robots. To avoid component impact during the rapid global reconfiguration and achieve smoothness of the reconfiguration process, a rotation rule for each rotating joint was designed and the kinematics model was used to simulate and validate the motion of the system’s end mechanism (front frame) and the entire robot system. Based on the kinematics model and the rotation rules of the rotating joints, a zero-moment point (ZMP) calculation model of the entire robot mechanism in the reconfiguration process was established, and the stability of the reconfiguration motions was evaluated based on the ZMP motion trajectory. The foot landing position was optimized to improve the robot’s stability during the reconfiguration. Finally, the smoothness and stability of the reconfiguration motion were further validated by testing the prototype of the metamorphic robot.

DEVELOPMENT OF A REHABILITATION ROBOT: MODELING AND TRAJECTORY TRACKING CONTROL

Recently, assistive robots have attracted great attention from researchers in the rehabilitation field. These types of robots support patients to perform designated movements during a training process. Despite the existence of commercial rehabilitation systems, growing demands for improvement in both hardware and control design are evident. Therefore, this paper introduces a prototype pneumatic artificial muscle-based assistive robot named BK-Gait and its control strategy for trajectory tracking purposes. Firstly, a brief description of the robot mechanism is presented. Secondly, the mathematical model of the robot’s actuator is built. Third, an active disturbance rejection control (ADRC) strategy is developed to enhance the tracking performance of the robot. Finally, multi scenarios experiments are carried out to evaluate the applicability of the robot and the proposed controller in the rehabilitation field.

Empirical optimization of an angled spoke paddling wheel with self-rotating mechanism

The development of the maritime industry has led to a corresponding increase in maritime accidents. Maritime accidents are major events that are costly to recover and can cause casualties. Moreover, individuals who are brought to the scene for recovery or rescue are at risk. To tackle this issue, the wheel mechanism of a water rescue robot, i.e., the angled spoke paddling wheel (ASPW), has been studied. The purpose of this study is to optimize the paddle design parameters of the ASPW using the Taguchi method. Experiments are conducted by creating paddles with various combinations of design parameters using {textbf{L}}_9(3^4) orthogonal arrays. The objective function is determining the optimal combination of paddle design parameters that will produce the greatest thrust force at the same RPM. Sensitivity analysis of each design parameter is conducted by calculating the signal-to-noise ratio from the experimental results. The pitch angle is found to be the most sensitive parameter. An additional experiment is conducted based on the results of the sensitivity analysis. The results show that the optimal design parameters are a pitch angle of 0^{circ }, rectangular end shape, X-axis curvature of 37.5 mm, and Y-axis curvature of 25 mm. The paddle with this combination of design parameters have a maximum thrust force of 64.74 gf at 120 RPM and exhibit up to an 18.27% improvement in performance compared with the initial paddle before optimization.

ROBOT TRAJECTORY PLANNING

The paper deals with the kinematic analysis of the robot model. The matrix method of kinematic analysis is used. The robot mechanism is an open kinematic chain. The position, velocity and acceleration vector of the end point of the robot arm is determined in the Matlab program. Computer simulation is also performed in the MSC Adams program.

Mobile robot path planning with reformative bat algorithm.

Mobile robot path planning has attracted much attention as a key technology in robotics research. In this paper, a reformative bat algorithm (RBA) for mobile robot path planning is proposed, which is employed as the control mechanism of robots. The Doppler effect is applied to frequency update to ameliorate RBA. When the robot is in motion, the Doppler effect can be adaptively compensated to prevent the robot from prematurely converging. In the velocity update and position update, chaotic map and dynamic disturbance coefficient are introduced respectively to enrich the population diversity and weaken the limitation of local optimum. Furthermore, Q-learning is incorporated into RBA to reasonably choose the loudness attenuation coefficient and the pulse emission enhancement coefficient to reconcile the trade-off between exploration and exploitation, while improving the local search capability of RBA. The simulation experiments are carried out in two different environments, where the success rate of RBA is 93.33% and 90%, respectively. Moreover, in terms of the results of success rate, path length and number of iterations, RBA has better robustness and can plan the optimal path in a relatively short time compared with other algorithms in this field, thus illustrating its validity and reliability. Eventually, by the aid of the Robot Operating System (ROS), the experimental results of real-world robot navigation indicate that RBA has satisfactory real-time performance and path planning effect, which can be considered as a crucial choice for dealing with path planning problems.

The Soft Ray-Inspired Robots Actuated by Solid-Liquid Interpenetrating Silicone-Based Dielectric Elastomer Actuator.

Dielectric elastomer actuators (DEAs) are widely used in robotics and artificial muscles because of their large energy densities and short response time. In this study, we developed two types of soft ray-inspired robots using solid-liquid interpenetrating silicone-based DEAs, named SIS DEAs. The optimized SIS DEA had an actuation strain of 79.8% at 20.43 kV/mm in a freestanding state, which was used as the muscle of the ray robot. To imitate the swimming behavior of the ray, the effect of the driving frequency on the velocity of the ray robot was explored. The ray robot achieved a maximum swimming rate of 5.7 mm/s when the driving frequency was ∼0.6 Hz. In addition, the steady-state and the transient simulation were carried out to reveal the mechanism of the ray robot's electro-swimming. The results revealed that the actuating deformation of the SIS DEAs caused the electro-deformation of the ray robot, and the periodical electro-deformation generated the high-speed vortex beneath the robot to push the ray robot forward. The high actuation strain in the freestanding state and the shape customizability of the SIS DEAs made it an ideal alternative to muscles for various soft robots.

Development of an Adaptive Wall-pressing Mechanism for an In-pipe Cleaning Robot

This paper proposes a novel adaptive wall-pressing mechanism for an in-pipe cleaning robot (ICR) which combines two type of self-adaptive mechanisms. Parametric modelling and optimization for the mechanism is proceeded in order to improve the carrying capacity and adaptability of the robot in the water supply pipeline. Force in the compression spring due to the self-weight of ICR is reduced by 31% after optimization. A virtual simulation platform is established to analyse the stability and obstacle-surmounting capacity of ICR under different pre-loading forces.

Robotic Edge Resource Allocation for Agricultural Cyber-Physical System

Cloud-aided robots are increasingly adopted in realizing Cyber-Physical-Social System (CPSS) to reduce human efforts and enhance the system performance with diverse robotic applications. However, the multi-hop distance from robot to cloud data centre elevates the data transfer delay that often inhibits the deadline-satisfied task execution of robotic applications. Thanks to edge computing, this issue can be well addressed by harnessing computing resources in proximity of data sources. As edge resources are constrained in energy and processing capacity, sharing resources among the tasks of multiple robotic applications is critical to ensure. Therefore, in this paper, we develop a congestion game-theoretic robotic edge resource allocation mechanism for CPSS, which not only maintains the Quality-of-Service (QoS) by meeting task completion deadlines but also satisfies the energy constraints of resources. Here, Agriculture 4.0 is considered as a use case for the proposed mechanism which can be extended for other domains. Nevertheless, the performance evaluation of proposed mechanism is conducted in an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iFogSim</i> simulated edge computing environment. In comparison with existing greedy, heuristic, and evolutionary benchmarks, our mechanism is proven to offer overall 20% improvement in deadline satisfaction, energy consumption, and resource utilization.

Silicon-based soft parallel robots 4D printing and multiphysics analysis

Four-dimensional printing has set the stage for a new generation of soft robotics. The applications of rigid planar parallel robotic manipulators are also significant because of their various desirable characteristics, such as lower inertia, higher payload, and high accuracy. However, rigid planar parallel robots are heavy and require different actuators and components. This study introduces a novel technique to produce a light three degrees of freedom soft parallel manipulator at a low cost, which can be stimulated easily. This technique allows researchers to customize the actuator’s design based on the requirement. The robot is made by 3D printing based on fused deposition modelling and a direct ink writing process. The design, development, and additive manufacturing of a soft parallel robot electrothermally driven by a linear silicon-based actuator and polylactic acid parts are presented. Silicon-based soft actuators replace the rigid conventional linear actuators in this study to drive the planar parallel manipulator. The actuation of actuators is conducted using simple heating compared to the conventional rigid actuator. Various heating approaches and configurations are compared and analysed to find the most suitable one for the effective linear stroke of the soft actuator. The finite element model is used to analyse the performance of the electrothermally silicon-ethanol soft actuators in ABAQUS. The kinematics of the planar parallel robotic manipulator are simulated in MATLAB to achieve its workspace. The final soft parallel robot mechanism and the active and passive links are fabricated and tested experimentally.

Wind Resistance Mechanism of an Anole Lizard-Inspired Climbing Robot.

The stable operation of climbing robots exposed to high winds is of great significance for the health-monitoring of structures. This study proposes an anole lizard-like climbing robot inspired by its superior wind resistance. First, the stability mechanism of the anole lizard body in adhesion and desorption is investigated by developing adhesion and desorption models, respectively. Then, the hypothesis that the anole lizard improves its adhesion and stability performance through abdominal adjustment and trunk swing is tested by developing a simplified body model and kinematic model. After that, the structures of the toe, limb, and multi-stage flexible torso of the anole lizard-like climbing robot are designed. Subsequently, the aerodynamic behavior of the proposed robot under high-speed airflow are investigated using finite element analysis. The results show that when there is no obstacle, the climbing robot generates the normal force to enhance toepad friction and adhesion by tuning the abdomen’s shape to create an air pressure difference between the back and abdomen. When there is an obstacle, a component force is obtained through periodic oscillation of the spine and tail to resist the frontal winds resulting from the vortex paths generated by the airflow behind the obstacle. These results confirm that the proposed hypothesis is correct. Finally, the adhesion and wind resistance performance of the anole lizard-like climbing robot is tested through the developed experimental platform. It is found that the adhesion force is equal to 50 N when the pre-pressure is 20 N. Further, it is shown that the normal pressure of the proposed robot can reach 76.6% of its weight in a high wind of 14 m/s.

4D Multiscale Origami Soft Robots: A Review.

Time-dependent shape-transferable soft robots are important for various intelligent applications in flexible electronics and bionics. Four-dimensional (4D) shape changes can offer versatile functional advantages during operations to soft robots that respond to external environmental stimuli, including heat, pH, light, electric, or pneumatic triggers. This review investigates the current advances in multiscale soft robots that can display 4D shape transformations. This review first focuses on material selection to demonstrate 4D origami-driven shape transformations. Second, this review investigates versatile fabrication strategies to form the 4D mechanical structures of soft robots. Third, this review surveys the folding, rolling, bending, and wrinkling mechanisms of soft robots during operation. Fourth, this review highlights the diverse applications of 4D origami-driven soft robots in actuators, sensors, and bionics. Finally, perspectives on future directions and challenges in the development of intelligent soft robots in real operational environments are discussed.

End-to-End From Human Hand Synergies to Robot Hand Tendon Routing

The human hand capabilities are paramount for highly dexterous manipulation interactions. Unfortunately, the limitations of current technologies make replicating such capabilities unfeasible. Although several works have focused on directly attempting to create robot hands able to mimic human ones closely, few of them have attempted to create generalizable platforms, where robotic hand mechanisms can be iteratively selected and customized to different tasks. In order to build highly dexterous robotic hands in the future, it is crucial to understand not only human manipulation, but also develop methods to leverage robotic mechanisms limitations to mimic human hand interactions accurately. In this letter, we propose an end-to-end framework capable of generating underactuated tendon routings that allow a generic robot hand model to reproduce desired observed human grasp motion synergies accurately. Our contributions are threefold: (1) an end to end framework to generate task-oriented robot hand tendon routings, with the potential to implement desired synergies, (2) a novel grammar based representation of robot hand tendon routings, and (3) a schematic visualization of robot hand tendon routings. The latter two contributions have the potential to embed and compare properties among robot hands. Our results in simulation show that the proposed method produces tendon routing mechanisms that are able to closely mimic the joint trajectories of human subjects performing the same experimental tasks, while achieving dynamically stable grasping postures.

Mechanics Analysis of Functional Origamis Applicable in Biomedical Robots

The origami principle of folding planar sheets into functional three-dimensional devices promises a future with increased compactness and reconfigurability of biomedical robots. To inspire new origami-based biomedical robots, we highlight two categories of origami patterns that are applicable to build compact actuators, deployable stents, and minimally invasive surgery devices. Due to the requirements in system integration, biocompatibility, and payload capability, the conventional paper-based origamis are converted to physical robots by replacing the zero-thickness facets and zero-width folds with thick panels and flexible hinges, respectively. Therefore, the physical origami-based robots become inhomogeneous, making it more complex and challenging to analyze their mechanics. So far, no such model can analyze the mechanics of any physical origami robot. Herein, we propose a computational model that discretizes the continuous structures into truss and spring elements to fulfill this goal. Based on the model, we simulate the identified origami structures under various boundary conditions to investigate their application in biomedical scenarios. This article is expected to accelerate the design iteration of new functional biomedical origami robots.

Feasibility of hydrodynamically activated valves for salp-like propulsion

Using valves to control the direction of internal flow for effective swimming, the jet-propulsion method of sea salp (a barrel-shaped marine invertebrate) provides a promising locomotion mechanism for bio-inspired robots. In this study, we numerically investigate this problem via an axisymmetric fluid–structure interaction model within the immersed-boundary framework. Specifically, we prove that in these systems, it is feasible to use fully passive valves whose opening and closing actions are driven solely by the hydrodynamic load. This finding is going to greatly reduce the complexity of locomotion devices based on this design. Furthermore, we have examined the effect of the design parameters, i.e., the stiffness and inertia, of the valves upon the swimming performance. In general, it is found that stiff and heavy valves increase the swimming speed, whereas soft and light valves decrease the cost of transport.

On the dynamics of multi-closed-chain robotic mechanisms

Here, a recursive technique based on the Gibbs–Appell (G–A) and the Newton’s impact formulas for dynamic modeling of multi-closed-loop mechanisms has been presented. Each closed loop of the said mechanisms comprises an arbitrary number of rigid links. The challenges encountered in the present research are the following: (1) the relatively large number of the dependent generalized coordinates, (2) how to deal with the holonomic constraints that govern each closed loop in the mentioned mechanisms, (3) dealing with the end effectors of these systems in a way that does not cause any restriction in the recursive method presented, and (4) considering the dynamic coupling between the loops of such linkages. In this article, all these challenges have been responded through the presented dynamic equations and graphical figures. Although the stated equations are valid for all types of linkages belonging to this class of robotic systems, a 4RRR mechanism has been selected as the case study in this work. This research is concluded by simulating the movements of the abovementioned mechanism in the impact and non-impact phases and validating the responses of the system by means of the work and energy principles.

Hardware Realization of Kinematic Mechanism and Control System of Multifunctional Industrial Robot

In order to improve the position control accuracy of industrial robots and solve the problems of poor real-time and reconfigurability of traditional motion controllers, a hardware implementation method for the motion mechanism and control system of multi-functional industrial robots is proposed. The video acquisition system is suitable for infrared detectors containing 4 channels or readout circuits in 4 channels. The video display system is compatible with the old AV/S-Video interface, and is also suitable for computer system video graphics array (VGA) analog video interface and high-definition video interface. Multimedia Interface (HDMI) digital high-definition video interface display terminal equipment. The hardware circuit of video acquisition and corresponding video interface image output is designed, including signal amplification circuit, analog-to-digital conversion circuit, video information buffer circuit, video display digital-to-analog conversion circuit, and interface hardware circuit, to realize the digitization of image information acquisition and image information. Display simulation, construct VGA, AV/S-Video, and HDMI timing sequence with hardware description language through Field programmable gate array (FPGA) to complete the display of corresponding terminal equipment. The experimental results show that the experimental data was substituted into the formula and the variance σ = 0.09 mm was found, indicating that the detection error of the system is less than 0.27 mm, which meets the detection requirements. Through the 3D contour reconstruction experiment of the workpiece, the expected function realization of each module is proved, and the feasibility of the system software and hardware system is verified. This design has good scalability and stability, reducing labor costs.

Leg Structure based on Counterbalance Mechanism for Environmental Adaptive Robot

Leg Structure based on Counterbalance Mechanism for Environmental Adaptive Robot

Performance evaluation of tape library systems

Magnetic tape provides a cost-effective way to retain the exponentially increasing volumes of data being produced. The low cost per gigabyte and the low energy consumption render tape a preferred option over hard disk drives and flash for infrequently accessed data. Assessing the performance of tape library systems is central to achieving appropriate storage provisioning and dimensioning. Performance is affected by the number and the operational characteristics of the tape drives and the robotic arms, and the mount and unmount policies deployed. In this paper, we develop a novel analytical model that accurately captures the principal aspects of tape library operation. Several relevant performance measures including the mean waiting time and the mount/unmount rates are derived. The model provides useful insights into the behavior of the tape libraries and yields results that enable a better understanding of the design tradeoffs. The validity of the model developed is confirmed by demonstrating a good agreement of the predicted performance with that obtained by simulation across various configurations. To mitigate the burden on the robotic mechanism, a scheme of accumulating multiple requests before sending them to the tape library is proposed and studied.

Modeling and Simulation of autonomous mobile robot system for collision avoidance in VR environment using Simscape-Multibody

Autonomous mobile robots have recently become a centre of attention in the robotics community due to their ease of design, modeling and implementation, making them very lucrative in logistics, monitoring, mapping and other purposes. Fundamentally, collision avoidance is a major aspect of an autonomous mobile robot which requires assistance from other aspects like sensor fusion, localization, path planning etc., to contribute to achieving proper functionality in an open environment, hence the inherently required integration makes it hard to many researchers, robotics and robot enthusiasts to incorporate multi-dimensional functionalities in their system. Sometimes traditional software for robotics makes it harder to acquire actual insight into their system due to a lack of cross-platform compatibility. Therefore, this research aims to demonstrate a way to integrate important aspects required for obstacle avoidance system for design and analysis using a compatible system which is SolidWorks and MatLab simscape multibody, which provides sufficient scope to properly and accurately simulate autonomous systems on a real-time basis that can be used with actual hardware to final implementation. The findings of the study demonstrate that it is very much feasible to use such a method for robotic and other complex mechanics applications, and further analysis of the sensor fusion algorithm reveals some shortcomings of the sensor fusing algorithm and data processing which can be avoided by introducing further sensor sequencing and implementing adaptive neuro fuzzy-based system.