Motion Profiles Research Articles

Super-twisting based sliding mode control of hydraulic actuator without velocity state

This paper provides a novel surface design and experimental evaluation of a super-twisting algorithm (STA) based control for hydraulic cylinder actuators. The proposed integral sliding surface allows to track a sufficiently smooth reference without using the velocity state which is hardly accessible in the noisy hydraulic systems. A design methodology based on LMI’s is given, and the STA gains are designed to be adjusted by only one free parameter. The feasibility and effectiveness of the proposed control method are shown on a standard hydraulic test bench with one linear degree of freedom and passive load, where a typical motion profile is tracked with a bounded average error below 1% from the total drive effective output.

Linearly polarized high sub-mode excited long-beaked fiber optic transmission and tracking particulate system

Micro/nano optical fibers are playing an increasingly important role in the fields of targeted drug therapy and biological cell analysis. To achieve fast and stable particle delivery, we designed a long beak-shaped fiber probe that not only increases the fiber optical field gradient force but also enhances the evanescent field around the probe. The evanescent field at the side of the fiber is further enhanced by exploiting the symmetrically distributed four-wave flap mode field of the linearly polarized high sub-mode in the weakly guided fiber, thus ensuring stable particle capture in the axial direction while improving the stability of lateral capture. We conducted a series of experiments using a long-beaked micro-nano fiber in LP21 mode to deliver polystyrene particles, and the results show that the probe can deliver particles rapidly at low input power, verifying the superiority of the long-beaked fiber probe. Finally, we built an FPI interference model to monitor the transport position of the particles in real-time. By processing the interference fringes, we plotted the motion profile of the particles, which helps to further manipulate the motion of the particles.

Collision-free and smooth motion planning of dual-arm Cartesian robot based on B-spline representation

This paper discusses a new approach to motion planning of dual-arm gantry kinematic that solves the self-collision problem while ensuring G2-continuity and low curvatures. Starting from collision-free start and target points, the proposed method defines the geometric path of the end-effectors with classical five-segment planar trajectories, described by fifth-degree B-splines. The rototranslation of the loaded parts is evaluated in frames to define sampled overlapping curves, used to compute splines that act as deviation curves being added on the previously defined geometric paths in order to prevent collisions. Here, a quadratic programming minimization is employed to reduce the curvature of these spline and preserve the kinematics properties of the initial path. The kinematic constraints of the axes are ensured by iso-parametric trajectory planning, which results in an optimized motion profile to reduce the task execution time. Finally, the proposed approach is applied to a sorting system for laser machine (LST) having a dual-arm 7-d.o.f. gantry kinematic. The results of a case study of a typical sorting operation are presented and discussed to illustrate and clarify the method. The approach presented in this work can be applied to other robotic systems with similar kinematic structures, providing a useful tool for motion planning in pick-and-place applications.

Analysis of an actively controlled composite box manipulator without external actuator

This study focuses on active vibration control for a single-link composite box manipulator by using a single actuator for driving and control actions. Model extraction and system identification techniques are studied to obtain mathematical models of the manipulator. The state space model is extracted from the finite element model using modal analysis conducted in ANSYS, while the system identification approach is an experimental modeling method using the input and output signals of the system. The input signals are defined as triangular and trapezoidal motion profiles, while the output signals are the acceleration signals of the manipulator. Proportional derivative and positive position feedback controllers are implemented on the obtained mathematical models to reduce residual vibrations. The simulation results are successfully verified by experiments, and uncontrolled/controlled results are evaluated with reduction rates.

Characterization of Biology-Guided Radiotherapy Accuracy as a Function of PET Tracer Uptake

To characterize the tracking capability and dosimetric accuracy of biology-guided radiotherapy (BgRT) under clinically relevant PET tracer uptake scenarios relative to the background. A custom-made anthropomorphic phantom filled with a liquid 18F-FDG solution including two embedded fillable 22 mm diameter spherical structures mimicking GTV (= CTV) and OAR was coupled to motion stages to create an independent 3D respiratory motion with 22 mm maximum range for target and a 5 mm 1D sinusoidal motion in the OAR. The biology-tracking zone (BTZ) was generated by adding 5 mm margin to the motion extent. The three BgRT scenarios studied were representative of tumors with good (8:1), borderline (4:1) and undesired (2:1) PET biodistributions compared to background. The clinical safety limit of BgRT uses Activity Concentration within the BTZ (AC ≥ 5 kBq/ml) and Normalized Target Signal as a contrast metric (NTS ≧ 2.7 for planning and ≧ 2 for delivery). The BgRT deliveries were repeated 3 times with radiochromic film and integrated ion chamber capturing the target and OAR doses. Tracked dosimetry was assessed using a margin-loss calculation defined as the maximum linear difference in distance between the planned and delivered 97% prescription iso-dose lines. The imaging-only PET images used to create BgRT plans had an AC of 7.0, 5.3, and 1.6 kBq/ml with an NTS of 6.8, 5.3, and 1.8 for 8:1, 4:1, and 2:1 concentrations, respectively. Qualitatively, the target was not visible on the planning PET images 2:1 loading scenario. At delivery, the mean pre-scan activity concentrations were 6.8, 4.7, and 3.7 kBq/ml with corresponding mean NTS of 3.7, 2.6, 1.5 for 8:1, 4:1 and 2:1 deliveries. The pre-scan values of AC or NTS did not satisfy the clinical system safety limits for 4:1 and 2:1 ratio experiments, but the engineering software allowed for the delivery to capture the resulting doses. The deliveries showed a prescription dose coverage to the CTV of 100% for the 8:1 and 4:1 cases, but 88% for the 2:1 case. When compared to the planned dose values, the delivered minimum doses were -7.6%, -8.6% and -10.9%, whereas the maximum dose differences in CTV were 1.2%, 0% and -4.8% of the planned dose distributions of the 8:1, 4:1 and 2:1 cases, respectively. Calculated margin losses were -2.3, -3.8, and -5.5 mm, for the 8:1, 4:1, and 2:1 cases, respectively. The maximum OAR doses were less than the maximum doses predicted on the bounded DVH curves for all scenarios. With sufficient tracer uptake in the target, BgRT can deliver tracked dosimetry for targets with a large respiratory motion profile. Both the good BgRT candidate and borderline cases produced clinically acceptable delivered doses, even though the borderline case was flagged by the clinical system safety checks. As expected, the delivered BgRT dose distributions were suboptimal with reduced tumor over background PET contrast.

Convective flow of hybrid nano particles in combination of TiO2+CuO/engine oil MoS2+ZnO/engine oil and Al2O3+Cu/engine oil with viscous dissipation over vertically moving surface: Numerical and Galerkin approach

Engine oil has a vast application sector as it is the most essential working lubricant for industrial machineries, engines of vehicles, and aircraft combustion processing. In order to find out more effective engine oil-based hybrid nanofluid in terms of heat transfer capabilities and to minimize the production cost, the novelty of our present study focused on three different combinations of nanoparticles (TiO2+CuO, MOS2+ZnO, and Al2O3+Cu) that are dispersed in Engine oil (EO). The fundamental aim is to examine the thermal and flow fluctuation of a convective dissipative engine oil-based hybrid nano liquid to understand the physical quantities and thermal properties over a vertically moving plate by employing the Galerkin Method (GM). Similarity variables are initiated to permute the set of governing equations into the nonlinear coupled ordinary differential equations along with Bc’s, which are solved using both numerical (Maple) and analytical method (GM). This MAPLE software uses the fourth-fifth-order Runge-Kutta-Fehlberg (RFK45) technique as a default function to solve numerically boundary value problems. Validation for this study has been conducted by comparison with previously published results. The results of the present study are given for both opposing and assisting flow with the distribution of fluid motion and temperature profiles, wall shear stress, and rate of heat transfer. The assisting flow has great significance on the flow velocity and temperature with increasing mixed convection parameters. The Brinkmann number and Prandtl number have a larger flow near the wall in temperature distribution and then increase and decrease respectively satisfying the asymptotic boundary conditions. Our results also reveal that the TiO2+CuO/Engine oil has a significant augment in terms of heat transfer than that of MoS2+ZnO/Engine oil and Al2O3+Cu/Engine oil.

Torque Minimization of Dynamically Decoupled 3R Spatial Serial Manipulators via Optimal Motion Generation

This paper proposes an analytically tractable solution for minimizing input torques in decoupled three-degrees-of-freedom spatial serial manipulators. The solution relies on the generation of motion using a «bang-bang» profile. The problem is solved in two stages. Firstly, the dynamic decoupling of the manipulator is accomplished through the redistribution of the moving masses and the relocation of one of the actuators. This leads to the decoupling of the equations of motion for different degrees of mobility. It is worth mentioning that this solution represents a symbiosis of two distinct approaches: the redistribution of link masses and the relocation of one of the manipulator actuators. This innovative approach to dynamic decoupling has not been previously proposed. At the second stage, the input torques of the actuators are reduced by generating motion profiles for the manipulator's links using the «bang-bang» law. Thus, thanks to the developed methodology, it becomes possible to reduce the energy consumption of high-speed manipulators by choosing the optimal planned motion of their links. To evaluate the effectiveness of this approach, numerical simulations are carried out using the ADAMS software. A comparative analysis of the trajectories generated by the fifth-order polynomial profile, widely used in industrial robots, and the «bang-bang» profile has been performed. The simulation results show act, the use of the «bang-bang» profile allows one to reduce the maximum values of the input torques. The developed technique allows designers to create high-speed manipulators featuring decoupled dynamics and diminished energy consumption.

Development of an impulsive motion generator inspired by cocking slip joint of snapping shrimp.

We propose an impulsive motion generator inspired by snapping shrimp. The proposed device mimics the geometrical arrangement of a unique claw joint calledcocking slip jointand integrates it with an artificial rack-pinion actuator mechanism rather than adopting the musculoskeletal system as it is. The design approach allows the proposed device to reproduce the impulsive slip motion through the torque reversal and unlatching mechanism of the underlying unique joint by using a single servo motor. Static and dynamic analyses revealed that the actuator force required to store and release elastic energy was remarkably small compared with the resulting acceleration force and rotation/tip speed. Through simulations and experiments, we validated the mechanical analyses and confirmed that the resulting ultrafast slip motion was comparable with the claw closure of snapping shrimp based on the cocking slip joint. Moreover, from an engineering perspective, the motion profiles are modifiable through design parameters, and the repeatability of the impulsive slip motion is satisfactory.

Artificial neural network modeling of mixed convection viscoelastic hybrid nanofluid across a circular cylinder with radiation effect: Case study

As a result of its use in the manufacturing and construction industries, research on the flow of nanofluid is rather well-known among academics and professionals in related fields. It is helpful for electrical equipment to utilize it for cooling reasons, which has shown promising results in terms of reducing energy use. As a result, the primary objective of this research is to inspect the impacts that radiation has on the mixed convection of Walters'-B hybridity nanofluid flow of stagnant point in a horizontal circular cylinder under the circumstances of a constant heat flux. It is considered a conventional fluid despite the presence of copper (Cu) and alumina (Al2O3) nanoparticles in the water (H2O) hybridity nanofluid. To make the solution to the resulting controlling system of equations more straightforward, the numerical approach of a neural network with a back-propagation algorithm (NN-BPA) is used. It follows by clarifying how various physical characteristics, such as blended convection, thermal radiation, and stagnant movement, affect temperature, skin friction, thermal transfer, velocity, and graphical profiles of those variables. The LMNN-BPA has the quickest processing algorithm and performs well in general, corresponding to the thorough analysis. Additionally, the mixed convective and viscoelastic properties exhibit both rising and dropping developments regarding skin friction and heat transmission.

Profile generation using the filtering technique for the fast motion and smooth performance in the hardware level of autonomous system

AbstractThis study addresses the challenge of motion control in autonomousvehicles through the introduction of a novel profile generation design. Specifically,autonomous vehicles often contend with uncertain factors and physicallimitations within their operational environments, such as abrupt changes inacceleration or intricate parametric motion profiles. To tackle this problem, afiltering technique for motion profile generation is proposed, leveraging ahardware programming language as its foundation. The investigation begins byanalyzing the specific structure of the mobile platform, which includes twoactive side wheels, two passive rear wheels, a high load capacity, and adifferential drive mode. Building upon this theoretical basis, the proposedfiltering technique is introduced to attain smooth motion profiles and optimizetiming. Furthermore, the study suggests the use of FPGA (Field ProgrammableGate Array) acceleration to expedite these computations for swift motionprocessing. To validate the efficacy of the proposed method, both the mobilevehicle and the load are simulated as a one‐axis linear ball‐screw system withan aluminum ruler. The experimental results unequivocally demonstrate theeffectiveness, feasibility, and applicability of the proposed approach across avariety of industrial solutions.

Influence of plunger motion profile of high pressure die casting on the casting porosity and solidification rate

Influence of plunger motion profile of high pressure die casting on the casting porosity and solidification rate

Effect of slope on smoke movement and temperature profile in underground utility tunnel

Effect of slope on smoke movement and temperature profile in underground utility tunnel

The Effect of Elbow Flexion On Valgus Carrying Angle

This study aimed to examine the effect of flexion on valgus carrying angle in the human elbow using a dynamic elbow testing apparatus. Active elbow motion was simulated in seven cadaveric upper extremities. Six electromechanical actuators simulated muscle action, while 6 degrees-of-freedom joint motion was measured with an optical tracking system to quantify the kinematics of the ulna with respect to the humerus as the elbow was flexed at the side position. Repeatability of the testing apparatus was assessed in a single elbow over five flexion-extension cycles. The varus angle change of each elbow was compared at different flexion angles with the arm at 0° of humerothoracic abduction or dependent arm position. The testing apparatus achieved excellent kinematic repeatability (intraclass correlation coefficient, >0.95) throughout flexion and extension. All elbows decreased their valgus carrying angle during flexion from 0° to 90° when the arm was maintained at 0° of humerothoracic abduction. Elbows underwent significant total varus angle change from full extension of 3.9° ± 3.4°(P = .007), 7.3° ± 5.2°(P = .01), and 8.9° ± 7.1°(P = .02) at 60°, 90°, and 120° of flexion, respectively. No significant varus angle change was observed between 0° and 30° of flexion(P = .66), 60° and 120° of flexion(P = .06), and 90° and 120° of flexion(P = .19). The dynamic elbow testing apparatus characterized a decrease of valgus carrying angle during elbow flexion and found that most varus angle changes occurred between 30° and 90° of flexion. All specimens underwent varus angle change until at least 90° of flexion. Our model establishes the anatomic decrease in valgus angle by flexion angle invitro and can serve as a baseline for testing motion profiles of arthroplasty designs and ligamentous reconstruction in the dependent arm position. Future investigations should focus on characterizing motion profile change as the arm is abducted away from the body.

Numerical Solutions of Casson-Nano Fluid Flow Past an Isothermal Permeable Stretching Sheet: MHD, Thermal Radiation and Transpiration Effects

The Runge-Kutta Shooting Technique may be used to discover numerical solutions by the absence of magnetic field, thermal radiation, then transpiration consequence for viscous, incompressible, electrically conducting with combination of Casson and Nano-fluids that approach an isothermal permeable non-linearly stretched sheet. The governing equations for this fluid flow were transformed keen on non-linear ODEs using the similarity quantities. Visualizations of velocities, temperatures, and concentrations illustrate the mathematics behind the issue. According to tabular data, these flow regulating factors affect the coefficient of friction for skin-friction, heat transfer, and mass flow coefficients. Program code validation literature has been compared to the new numerical findings. It has been shown that flow characteristics are greatly affected by the amount of air that is exhaled. The study’s applications include industrial Nano-technological manufacturing processes. In this current work, the speed profiles are diminishing growing values of Casson fluid limitation as well as decreases by growing values of Magnetic field & Suction/Injection parameters. With increasing effects Brownian motion and Thermophoresis temperature profiles are increase. As the values of Thermal radiation of limitation enhances, the temperature profiles are also increases. The concentration profiles are increasing with increasing values of Thermophoresis parameter and reverse effect observed in case of Brownian motion effect. Also, concentration profiles decreases with increasing values of Lewis number.

Five-axis parallel mechanism system (PMS) CNC partial link control system based on modified inverse kinematic of 6-DOF UPS parallel manipulator

This paper presents a control system algorithm for a five-axis parallel mechanism system (PMS) CNC milling machine based on a 6-DOF Stewart platform parallel manipulator with a universal-prismatic-spherical (UPS) configuration. The control system reads the G-Code commands as standard CNC machine language, then extract data points and interpolates them to generate the robot trajectory patterns as motion references. Then, the control system uses the modified inverse kinematic equation to determine the length of each link to move the end effector to track the trajectory patterns from the previous G-code extraction process. The inverse kinematic equation is modified especially for the five-axis PMS CNC milling machine by including machine-offset and tools-offset parameters so it will be easier for the control system to implement the kinematic equation. As expected, the system simulation results successfully followed the G-Code program moving commands. The average error of the length control system is 0,1 mm, while the average error of the length change rate control system is 1,8 mm/s. The maximum error is 26.9 mm was caused by the system's inability to follow the motion profile in transient. It can be concluded that 6-DOF Stewart platform parallel structures,which provide better performance than serial structures, can be implemented as a new concept for the motion mechanism of five-axis CNC milling machines. The five-axis PMS CNC milling machine also promises better performance than conventional five-axis gantry structures CNC.

Vibration Control of Flexible Manipulators by Active Cable Tension

The end point vibrations of the serial manipulator should be controlled during motion or working process. In this study the residual vibrations of the flexible manipulator were controlled with cable tensions. The finite element model was established in ANSYS Mechanical APDL. The open loop and closed loop control simulations were performed under the trapezoidal velocity motion profiles. Zero and three different initial strain values were assigned to the cables. As a result, the end point vibration amplitudes, axial forces of the cables and the bending strain values of the one element near the fixed end were observed in order to define the limitations of the sensors and actuators which will be selected for experimental setup.

A study of the water quality parameter and its impact using HYDRUS-1D in Deepor Beel, Guwahati, Assam

This study focuses on knowing the status of 12 water quality parameters with their variation and soil-solute interaction due to dumping of wastes at six different locations of Deepor Beel (a Ramsar site), finding their necessary correlations and development of a solute transport model using HYDRUS-1D software. HYDRUS-1D model used in this study will show the movement of iron through the soil profile in the area selected near the Municipal dumping yard at Boragaon. The results indicated that certain parameters are higher than their standard permissible limits with its extreme values obtained at the dumping location at Boragaon. The water near the dumping site is acidic (pH= 5.92), with high iron concentrations (3.68 mg/l), increasing hardness and turbidity as well as lower D.O level (3.67 mg/l). HYDRUS-1D solute transport model gives a distinct and clear picture of the solute movement, water flow, water content, pressure head and concentration profile variation along the soil profile with respect to time and depth. The results of this model showed that continuous influx of harmful solutes on the surface of the Deepor Beel could lead to break through of this solute through the soil column into the groundwater storage. Hence the present study showed that water quality is deteriorating at various locations of the beel and necessary steps are immediately required for sustaining the ecological balance of the wetland.

Study on wear debris characteristics of different polyethylene under reciprocating sliding and compound motion modes

The UHMWPE wear debris has become an important reason affecting the service life and clinical reliability of the prosthesis. In order to further reveal the wear debris characteristics, three kinds of UHMWPE materials including non-crosslinked UHMWPE (UPE), Crosslinked UHMWPE (XLPE) and E-vitamin doped UHMWPE (EXPE) were taken as research objects, and the quantity, size, morphology and distribution characteristics of wear debris under reciprocating sliding and compound motion modes were systematically studied. Among them, the ball-on-disk samples were adopted under reciprocating sliding, and the real ball-on-socket contact mode of artificial cervical disc prosthesis was adopted under compound motion. The tribological experiments were performed with the frequency of 2Hz under 50,000 cycles with newborn bovine serum solution. The results showed that the dominant wear mechanism was abrasive wear accompanied by fatigue cracks under reciprocating sliding mode, while adhesive wear accompanied by a few abrasive wear under compound motion mode. Compared with the quantity of wear debris under reciprocating sliding mode, the number of UHMWPE debris under composite motion mode was reduced by 28.8%, 31.4% and 37.1% for UPE, XLPE and EXPE debris, respectively. The debris results of the three different polymers were consistent in the quantity, size range, morphology and distribution, but different in the size distribution characteristics. The largest proportion of EXPE debris size occurred in the range of less than 1 μm, while the largest proportion of UPE and XLPE debris size ranges from 1 to 5 μm under reciprocating sliding mode. When the debris size was in the range of 1–5 μm under compound motion mode, it accounted for the largest proportion with a value of 55.7%, 66.7% and 74.0% for UPE, XLPE and EXPE debris, respectively. The UHMWPE debris morphology included six main types: spherical, flakes, rods, fibrillar, granular, and other types. Granular and “other types” debris were the dominant types and the sum proportion of these two types of debris for the three kinds of UHMWPE materials was all as high as 80%. Hence, the material type, pair shape, load and movement profiles may have more or less influence on the quantity, size, morphology and distribution characteristics of UHMWPE debris.

Snapture—a Novel Neural Architecture for Combined Static and Dynamic Hand Gesture Recognition

As robots are expected to get more involved in people’s everyday lives, frameworks that enable intuitive user interfaces are in demand. Hand gesture recognition systems provide a natural way of communication and, thus, are an integral part of seamless human-robot interaction (HRI). Recent years have witnessed an immense evolution of computational models powered by deep learning. However, state-of-the-art models fall short of expanding across different gesture domains, such as emblems and co-speech. In this paper, we propose a novel hybrid hand gesture recognition system. Our Snapture architecture enables learning both static and dynamic gestures: by capturing a so-called snapshot of the gesture performance at its peak, we integrate the hand pose and the dynamic movement. Moreover, we present a method for analyzing the motion profile of a gesture to uncover its dynamic characteristics, which allows regulating a static channel based on the amount of motion. Our evaluation demonstrates the superiority of our approach on two gesture benchmarks compared to a state-of-the-art CNNLSTM baseline. Our analysis on a gesture class basis unveils the potential of our Snapture architecture for performance improvements using RGB data. Thanks to its modular implementation, our framework allows the integration of other multimodal data, like facial expressions and head tracking, which are essential cues in HRI scenarios, into one architecture. Thus, our work contributes both to integrative gesture recognition research and machine learning applications for non-verbal communication with robots.

A hybrid polymer–water peridynamics model for ballistic penetration damage of soft materials

Numerically understanding the dynamic response of soft materials subject to high-speed penetration is crucial for advancing transdermal delivery technologies and analyzing injuries related to ballistics. Due to the complexity in material correspondence models and the difficulty of simulating high-speed impact damage problems using traditional mesh-based numerical techniques, precisely capturing mechanical behaviors of soft materials following ballistic penetration remains challenging. This work proposes a novel hybrid polymer–water model within the peridynamics (PD) framework to accurately clarify the complex damage process of soft materials subject to ballistic penetration. We propose the hybrid interactions comprising of water–water, polymer–polymer, and polymer–water interactions, which embodies the subscale nature of various components and captures the constitutive features of soft materials. A novel decomposition scheme for the deformation gradient is proposed to overcome the limitations in traditional non-ordinary state-based PD where only homogeneous particles are involved in the influence domain, extending the scope of PD theory to mixed material systems. The superior effectiveness and applicability of proposed model are demonstrated through compression, shear, fracture tests. Regarding to the case of high-velocity penetration, both motion profiles of projectile and pressure profiles of gelatin after penetration can be captured in line with physics awareness. The proposed model offers a reasonable and practical representation of soft material from the perspective of a particle-based approach and enhances the potential applications of PD framework for simulating large deformation and dynamic response of soft materials.