Mechanical Arm Research Articles

Design and 3D Printing of Stretchable Conductor with High Dynamic Stability.

As an indispensable part of wearable devices and mechanical arms, stretchable conductors have received extensive attention in recent years. The design of a high-dynamic-stability, stretchable conductor is the key technology to ensure the normal transmission of electrical signals and electrical energy of wearable devices under large mechanical deformation, which has always been an important research topic domestically and abroad. In this paper, a stretchable conductor with a linear bunch structure is designed and prepared by combining numerical modeling and simulation with 3D printing technology. The stretchable conductor consists of a 3D-printed bunch-structured equiwall elastic insulating resin tube and internally filled free-deformable liquid metal. This conductor has a very high conductivity exceeding 104 S cm-1, good stretchability with an elongation at break exceeding 50%, and great tensile stability, with a relative change in resistance of only about 1% at 50% tensile strain. Finally, this paper demonstrates it as a headphone cable (transmitting electrical signals) and a mobile phone charging wire (transmitting electrical energy), which proves its good mechanical and electrical properties and shows good application potential.

Stability Optimization Simulation of Industrial Robot in ROS Environment

This paper studies the end actuator motion state of an RRR industrial robot, and gives a bottom up decision-making scheme based on PID algorithm. Under the background of complex industrial control, any environmental factors will have a deep effect on the accuracy. The physical representation of the accuracy of the end effector is the electrical signal. Foscus on the signal difference from joint to joint, based on the ROS and gazebo, the simulation of the RRR mechanical arm model can theoretically and intuitively Reflect the differences. To minimize the error, proportional–integral–derivative controller will be sued in this model and then Adjust PID parameters of each controller. Assume that the external interference is a linear superposition of impulse signals. The impulse response which the model makes should return to normal as soon as possible. In this way, the purpose of anti-interference is achieved. At the same time, it focuses on solving the motion state of industrial manipulator. For general industrial robots, its actuator, a gripper, should have the function of reaching any position and taking any direction in a certain space area. In other words, if a reference frame o 'is fixed on the center of the hand claw, the robot can send o' to any direction at any position in the space area. The position and direction of the gripper are determined by the amount of motion from the base to the gripper pairs. In addition, with the rapid development of the Internet, image has become a common form of information. This paper will use image recognition technology to provide the required detection data and reference values for the PID controller. Thus, the workspace of the industrial robot can be reflected more completely.

Mechanical Design, Planning, and Control for Legged Robots in Distillation Columns

Abstract Dexterous robots have great potential to execute industrial tasks that are not suited to humans. In this work, a novel robotic mobility platform is proposed for use in the chemical industry to enable autonomous distillation column inspection—a tedious and dangerous task for humans. A roller arm mechanism is designed for a quadrupedal robot that enables moving across the distillation column. Required dynamic behaviors are generated with full-body motion planning and low-level control. The holistic process of mechanical design, planning, and control leads to desired behavior, as demonstrated by high-fidelity simulations. This marks a key step toward operating legged robots inside distillation columns.

Dynamics of the Rotating Arm of an Electromechanical System Subjected to the Action of Circularly Placed Magnets: Numerical Study and Experiment

This paper considers the experimental and numerical study of an electromechanical arm powered by a DC motor and subjected to the action of permanent magnets. The magnetic torques arise from permanent magnets mounted at the free end of the arm and along a circle. The electrical subsystem is powered by two forms of input signal (DC and AC voltage sources). For each case, we determine the condition for complete rotation of the mechanical arm versus the parameters of the system such as the arm length, the number of magnets, and the frequency of the external signal. The nonlinear dynamics of the system is examined by means of time-histories, bifurcation diagrams, Lyapunov exponents and phase portraits. Chaotic and periodic dynamics are detected numerically and confirmed experimentally.

Nezha-F: Design and Analysis of a Foldable and Self-Deployable HAUV

This letter introduces a small hybrid aerial underwater vehicle (HAUV), which we named Nezha-F, that can fly in the air, perform vertical profiling underwater, and vertically take off and land from both the water surface and ground. A foldable and self-deployable arm mechanism linked to and driven by a piston variable buoyancy system (PVBS) is proposed to reduce the excessive underwater drag caused by aerial structures. By having a compact size and successfully balanced aerial and underwater performance without adding excessive actuators, this design provides a feasible idea for the miniaturization of amphibious floats. The dynamic characteristics of the small PVBS are linear fitted, and modeled. The originally nonlinear actuator performance is linearized by the post-fitting mapping. Asymmetric dead zones of the actuator are removed by adding compensation to the algorithm. During a 10-day field test, the vehicle showed good aerial performance and underwater control effect. Several full mission cycle tests proved the vehicle's ability in semi-autonomous operation and robust domain crossing and verified the vehicle's endurance during each mission stage.

Development of a Novel 4-DOF Flexible Endoscopic Robot Using Cable-Driven Multisegment Continuum Mechanisms

Abstract This paper presents the design, analysis, and development of a novel four degrees of freedom (4-DOF) endoscopic robot with cable-driven multisegment flexible continuum mechanisms. The endoscopic robot is mainly composed of the passive positioning arm, cable-pulley system, and 3-DOF flexible continuum mechanism. The forward and inverse kinematics of the endoscopic robot are derived based on the constant curvature assumption, and its working space, flexibility, and preoperative incision determination method are analyzed as well. Based on the hardware structure of the robot system, a control strategy and a control software are developed, and the continuum mechanism is kinematically calibrated to carry out the trajectory planning experiment and simulated surgery experiment. The experimental results show that the calibrated constant curvature model can be used for the motion control of the continuum mechanism, and the 4-DOF endoscopic robot can meet the visual field requirements of minimally invasive surgery.

Real-Time Recognition and Localization Based on Improved YOLOv5s for Robot's Picking Clustered Fruits of Chilies.

Chili recognition is one of the critical technologies for robots to pick chilies. The robots need locate the fruit. Furthermore, chilies are always planted intensively and their fruits are always clustered. It is a challenge to recognize and locate the chilies that are blocked by branches and leaves, or other chilies. However, little is known about the recognition algorithms considering this situation. Failure to solve this problem will mean that the robot cannot accurately locate and collect chilies, which may even damage the picking robot's mechanical arm and end effector. Additionally, most of the existing ground target recognition algorithms are relatively complex, and there are many problems, such as numerous parameters and calculations. Many of the existing models have high requirements for hardware and poor portability. It is very difficult to perform these algorithms if the picking robots have limited computing and battery power. In view of these practical issues, we propose a target recognition-location scheme GNPD-YOLOv5s based on improved YOLOv5s in order to automatically identify the occluded and non-occluded chilies. Firstly, the lightweight optimization for Ghost module is introduced into our scheme. Secondly, pruning and distilling the model is designed to further reduce the number of parameters. Finally, the experimental data show that compared with the YOLOv5s model, the floating point operation number of the GNPD-YOLOv5s scheme is reduced by 40.9%, the model size is reduced by 46.6%, and the reasoning speed is accelerated from 29 ms/frame to 14 ms/frame. At the same time, the Mean Accuracy Precision (MAP) is reduced by 1.3%. Our model implements a lightweight network model and target recognition in the dense environment at a small cost. In our locating experiments, the maximum depth locating chili error is 1.84 mm, which meets the needs of a chili picking robot for chili recognition.

Mechanical arm(s) driven by Josephson junction circuit(s), mimicking the movement pattern of myriapods

The major interest of this article is to investigate a single and an array of mechanical arms driven by Josephson junction (JJ) circuits and their applications in mimicking the locomotion of myriapods. Stability analysis of a single mechanical arm driven by a JJ circuit resulted in two equilibrium points and a switch of their stability for specific values of the stimulation current. Results of the numerical simulations reproduce the motion of myriapods in agreement with existing results and the proposed electromechanical system overcomes the difficulties of coupling many JJ circuits or other models of neuron circuits in actuating a single mechanical arm for mimicking the locomotion of myriapods. Actuation of the mechanical arm driven by a JJ circuit is confirmed by numerical simulations which are sensitive to the action of the electromagnetic signal and the effect of mass. The progressive excitation of the mechanical arms of the array of the electromechanical system as demonstrated by the numerical simulations is similar to the straightforward motion of myriapods.

A Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Hollow Hemisphere Dielectric Layer

Capacitive pressure sensors based on porous structures have been widely researched and applied to a variety of practical applications. To date, it remains a big challenge to develop a capacitive pressure sensor with a high sensitivity and good linearity over a wide pressure range. In this paper, a sensitive, flexible, porous capacitive pressure sensor was designed and manufactured by means of the "salt template method" and man-made grooves. To this aim, the size of the salt particles used for forming pores/air voids, time taken for thorough dissolution of salt particles, and the depth of the man-made groove by a pin were taken into consideration to achieve a better effect. With pores and the groove, the sensor is more liable be compressed, which will result in a dramatic decrease in distance between the two electrodes and a conspicuous increase of the effective dielectric constant. The optimize-designed sensor represents a sensitivity 6-8 times more than the sensor without the groove in the pressure range of 0-10 kPa, not to mention the sensor without pores or the groove, and it can keep good linearity within the measurement range (0-50 kPa). Besides, the sensor shows a low detection limit of 3.5 Pa and a fast response speed (≈50 ms), which makes it possible to detect a tiny applied pressure immediately. The fabricated sensor can be applied to wearable devices to monitor finger and wrist bending, and it can be used in the object identification of mechanical claws and object cutting of mechanical arms, and so on.

A novel pollination robot for kiwifruit flower based on preferential flowers selection and precisely target

Manual pollination of kiwifruit flowers is a labor-intensive work that is highly desired to be replaced by mechanical/robotic operations. In this application note, a pollination robot was developed for achieving precision pollination of kiwifruit flowers in orchard. The pollination robot consists of five systems include vision system, air–liquid spray system, mechanical arm, crawler-type chassis, and control system, which could select suitable flowers and then target to their pistil for precision pollination. Field experiments were conducted in a commercial kiwifruit orchard to evaluate its feasibility and performance, which achieved an average pollination success rate of 99.3% with an average fruit set rate of 88.5%. Furthermore, compared to artificial assisted pollination methods, it could improve utilization rate of kiwifruit pollen with an average consumption of 0.15 g in 60 flowers. The validations demonstrated that this pollination robot could achieve efficient pollination for kiwifruit flowers and save pollen.

A novel submersible-mounted sediment pressure-retaining sampler at full ocean depth

High-efficiency pressure-retaining sampling technology for obtaining seabed sediments is required for studying marine geological history, the survival principles of marine microorganisms, and the evolution of earth life. In this paper, a novel submersible-mounted sampler capable of collecting pressure-retained samples at a full ocean depth is designed. The structure scheme is first presented, including the sampling unit, pressure-retaining unit, and pressure-compensation unit. The sampling kinematics model is then established, and the influences of pressing velocity, and the length and inner diameter of pressure pipe on the pressing force of the mechanical arm are determined, providing important guidance for the design of the sealing structure. The maximum working depth of the sampler is 11,000 m, the coring diameter of the sampler is 54 mm, the maximum coring depth is 500 mm, and obtained samples can keep close to in-situ pressures. The sampler can be mounted on a submersible and operated using a single mechanical arm. During cruise TS-21 from August to October 2021, the sampler was deployed 4 times at depth of 7700 m in the West Philippine Basin, and the high pressure sediment samples were successfully collected. The pressure change of the samples remained within ±6%, which verified the rationality of the design and the feasibility of this novel submersible-mounted pressure-retaining sampler.

RJVS: A novel, compact and integrated rotating joint with variable stiffness

A variable stiffness joint is a key element for structural deformation, which is widely used in morphing mechanisms including mechanical arms, folding wings, etc. By adjusting the stiffness of the joint according to the external environment and/or system instruction, the motion response of the mechanical system can be controlled and its security and stability can be guaranteed. However, to develop a variable stiffness joint with small size and large bearing capacity is still challenging. Also, an accurate mathematical model and control method to describe the variable stiffness joint is very important. In this paper, a novel, compact and integrated rotating joint with variable stiffness is developed, whose rotational stiffness and motion can be real-time controlled. A new configuration of a stiffness-adjusting module with superior mechanical properties is proposed by changing the arm length of cantilever leaf springs. Then a universal mechanical model of stiffness which adapts to a wide range of deformation is proposed. The status of the stiffness-adjusting module is changed by rope driven in order to minize the structure. Angular displacement sensors and torque sensors are integrated to observe the static and dynamic performance of the joint. According to the established rotational stiffness model, the stiffness of the joint is adjusted by reverse calculation of the motor’s rotating angle. A nonlinear Proportion-Integral-Derivative method based on a Genetic Algorithm is proposed for motion control. The experimental results show that the proposed joint, with large bearing capacity and a wide range of stiffness adjustment, has integration functions of driving and sensing, and can achieve a good motion control performance.

Biological Eagle-eye Inspired Target Detection for Unmanned Aerial Vehicles Equipped with a Manipulator

Inspired by eagle eye mechanisms, the structure and information processing characteristics of the eagle’s visual system are used for the target capture task of an unmanned aerial vehicle (UAV) with a mechanical arm. In this paper, a novel eagle-eye inspired multi-camera sensor and a saliency detection method are proposed. A combined camera system is built by simulating the double fovea structure on the eagle retina. A saliency target detection method based on the eagle midbrain inhibition mechanism is proposed by measuring the static saliency information and dynamic features. Thus, salient targets can be accurately detected through the collaborative work between different cameras of the proposed multi-camera sensor. Experimental results show that the eagle-eye inspired visual system is able to continuously detect targets in outdoor scenes and that the proposed algorithm has a strong inhibitory effect on moving background interference.

Smart Multipurpose Surveillance Robot

The various sensors, mechanical arms, wheel system, wireless communication mechanism and remote controlling mechanism are used to design the proposed robot that can be used in military and civil fields. The coordination of smart robot various parts to perform different fields are discussed in this project. Our project deals with a multi-purpose robot that has been designed in such a way that it can fulfil the needs of the military, police, spy teams and armed forces. It has numerous applications and can be used in different environments and for different situations. This robotic vehicle uses a specific set of sensors for performing various tasks such as the PIR (passive infrared) sensor that detect the alive humans by emitting the infrared rays, as an alive human (body) emits thermal radiation, this thermal radiation is detected by the PIR sensor in order to detect alive humans, the bomb (metal) sensor is used for the detection of bombs, the fire or flame sensor is used for fire detection and the gas sensor, which is used to detect harmful gases. The robot is designed in such a way that it can perform multiple operations which is achieved by embedding different features into a single prototype.

The choice of degrees of freedom of automatic refueling manipulator

Traditional artificial gas station come on all the required 5 to 6 minutes, peak even 10 minutes or so, along with our country automobile holdings continued to increase, how to improve fuel efficiency become an important problem of gas station, according to the above problem, non-inductive refueling “AI” is put forward to cooperate with mechanical arm instead of artificial gas, this scheme can make the refueling time reduced to 3 minutes, Greatly improve refueling efficiency, and reduce labor costs. The manipulator adopts a tandem joint robot with a 2-DOF BB wrist at the wrist and a fixed base, which is driven by the servo motor of each joint as a whole. The end-effector is equipped with a cap opening device, a clamping device and an oil feeding device to open the oil tank cover, unscrew the seal plug and oil feeding tasks respectively.

The design of a manipulator drive system based on the main control chip

This paper mainly studies and designs the control system of a four-degree-of-freedom manipulator. As a motion control system, the control system is mainly oriented to the bottom, striving to develop an industrial manipulator system with high stability, strong reliability, and accurate positioning. Firstly, according to the control requirements of the mechanical arm system, a single CPU system control scheme is designed as a whole, that is, to control the steering gear rotation by controlling the duty cycle of the PWM wave output by the central controller, to achieve the position control of each joint. In terms of hardware, the main components are ARM microprocessor STM32F103ZET6, MG995 steering gear, MG945 steering gear, ultrasonic sensor, and power module. The joint motion control system is built by building a hardware platform and designing a software control program. In software design, the control program is divided into an initialization module and an operation module according to the modular design idea, and the program of each module is designed separately.

Kinematics Model Optimization Algorithm for Six Degrees of Freedom Parallel Platform

The attitude closed-loop control of the parallel platform in the working space needs to determine the relationship between the pose of the top moving platform and the length of each mechanical arm, that is, the kinematics problem of the parallel platform. In this study, the kinematics model of the six-degree-of-freedom parallel platform was established. The kinematics forward solution algorithm based on Newton–Raphson iteration was studied. The kinematics forward solution method usually adopts a numerical solution, which often needs multiple iterations, and the algorithm has a poor real-time performance. In order to improve the real-time performance of the parallel platform control system, a multivariate polynomial regression kinematics forward solution algorithm is proposed in this paper. Moreover, by combining the multivariate polynomial regression with the Newton iterative method, we obtained an efficient solution algorithm with controllable solution accuracy. The effectiveness of the proposed method was verified by simulation tests and physical tests.

Obstacle-avoidance path planning based on the improved artificial potential field for a 5 degrees of freedom bending robot

Abstract. Path planning is a key technique used in the operation of bending robots. In this paper, an obstacle-avoidance path-planning method of a 5 degrees of freedom (5 DOF) bending robot based on improved artificial potential field is proposed. Firstly, a connecting-rod coordinate system of the 5 DOF Cartesian bending robot is established to determine an equation of motion trajectory of the bending robot. Secondly, in view of the problem of the local minimum in the artificial potential field (APF) method and the failure of path planning, an improved APF path-planning method based on a rapidly exploring random tree (RRT) algorithm is proposed, which reduces the length of the path and enhances path smoothness. Finally, through simulation and obstacle-avoidance experiments on the path of a mechanical arm, effective path planning based on the improved APF method is verified. The experimental results show that the proposed path-planning method can plan an optimal path and meet the technical requirements of bending robot operations.

A new full closed-loop brain-machine interface approach based on neural activity: A study based on modeling and experimental studies

BackgroundThe bidirectional brain-machine interfaces algorithms are machines that decode neural response in order to control the external device and encode position of artificial limb to proper electrical stimulation, so that the interface between brain and machine closes. Most BMI researchers typically consider four basic elements: recording technology to extract brain activity, decoding algorithm to translate brain activity to the predicted movement of the external device, external device (prosthetic limb such as a robotic arm), and encoding interface to convert the motion of the external machine to set of the electrical stimulation of the brain. New methodIn this paper, we develop a novel approach for bidirectional brain-machine interface (BMI). First, we propose a neural network model for sensory cortex (S1) connected to the neural network model of motor cortex (M1) considering the topographic mapping between S1 and M1. We use 4-box model in S1 and 4-box in M1 so that each box contains 500 neurons. Individual boxes include inhibitory and excitatory neurons and synapses. Next, we develop a new BMI algorithm based on neural activity. The main concept of this BMI algorithm is to close the loop between brain and mechaical external device. ResultsThe sensory interface as encoding algorithm convert the location of the external device (artificial limb) into the electrical stimulation which excite the S1 model. The motor interface as decoding algorithm convert neural recordings from the M1 model into a force which causes the movement of the external device. We present the simulation results for the on line BMI which means that there is a real time information exchange between 9 boxes and 4 boxes of S1-M1 network model and the external device. Also, off line information exchange between brain of five anesthetized rats and externnal device was performed. The proposed BMI algorithm has succeeded in controlling the movement of the mechanical arm towards the target area on simulation and experimental data, so that the BMI algorithm shows acceptable WTPE and the average number of iterations of the algorithm in reaching artificial limb to the target region.Comparison with existing methods and Conclusions: In order to confirm the simulation results the 9-box model of S1-M1 network was developed and the valid “spike train” algorithm, which has good results on real data, is used to compare the performance accuracy of the proposed BMI algorithm versus “spike train” algorithm on simulation and off line experimental data of anesthetized rats. Quantitative and qualitative results confirm the proper performance of the proposed algorithm compared to algorithm “spike train” on simulations and experimental data.

Deformation Mechanism and Control of In-Situ Assembling Caisson Technology in Soft Soil Area under Field Measurement and Numerical Simulation.

With urban space becoming much more crowded, the construction of underground spaces continues to expand to deeper, and the requirements for the large depth and minor deformation in urban engineering construction are getting more urgent. A new kind of in-situ assembling caisson technology (called VSM) is a vertical shaft method (VSM), which excavates the stratum under water with a mechanical arm and assembles the prefabricated caisson segments at the same time. This paper takes the Shanghai Zhuyuan Bailonggang Sewage Connecting Pipe Project as an example, which is the first construction project in the soft soil area, such as Shanghai, and makes a technical analysis of the VSM by comparing the field measurement and numerical simulation. Ground settlements and layered deep displacements were monitored in the field measurement during the VSM construction. It shows that the maximum ground settlement caused by the VSM is 15.2 mm and the maximum horizontal displacement is 3.74 mm. The influence range of the shaft excavation on the ground settlement is about 30 m away from the shaft center. The results demonstrate that the VSM construction has great applicability in the soft soil area. A finite element simulation model of the VSM shaft is established and verified by field measurement. There is a certain error between the traditional theoretical calculation by analogy to the common retaining walls of the deep foundation pit and the measured results, while the simulation results are relatively consistent with field measurements. The reasons for the difference are well-analyzed. Finally, the effects of the VSM construction method on the engineering environment are analyzed, and the suggestions for deformation control in the future are put forward.