Kinematic Design Research Articles

A Novel Clinical-Driven Design for Robotic Hand Rehabilitation: Combining Sensory Training, Effortless Setup, and Large Range of Motion in a Palmar Device.

Neurorehabilitation research suggests that not only high training intensity, but also somatosensory information plays a fundamental role in the recovery of stroke patients. Yet, there is currently a lack of easy-to-use robotic solutions for sensorimotor hand rehabilitation. We addressed this shortcoming by developing a novel clinical-driven robotic hand rehabilitation device, which is capable of fine haptic rendering, and that supports physiological full flexion/extension of the fingers while offering an effortless setup. Our palmar design, based on a parallelogram coupled to a principal revolute joint, introduces the following novelties: (1) While allowing for an effortless installation of the user's hand, it offers large range of motion of the fingers (full extension to 180° flexion). (2) The kinematic design ensures that all fingers are supported through the full range of motion and that the little finger does not lose contact with the finger support in extension. (3) We took into consideration that a handle is usually comfortably grasped such that its longitudinal axis runs obliquely from the metacarpophalangeal joint of the index finger to the base of the hypothenar eminence. (4) The fingertip path was optimized to guarantee physiologically correct finger movements for a large variety of hand sizes. Moreover, the device possesses a high mechanical transparency, which was achieved using a backdrivable cable transmission. The transparency was further improved with the implementation of friction and gravity compensation. In a test with six healthy participants, the root mean square of the human-robot interaction force was found to remain as low as 1.37 N in a dynamic task. With its clinical-driven design and easy-to-use setup, our robotic device for hand sensorimotor rehabilitation has the potential for high clinical acceptance, applicability and effectiveness.

Robust path-following control of underactuated AUVs with multiple uncertainties and state constraints

This paper proposes a novel robust controller for horizontal path-following problem of an underactuated AUV subject to multiple uncertainties and state constraints. Firstly, four reduced-order extended state observes (ESOs) are designed to estimate the multiple uncertainties, and the estimated values are adopted in the design of kinematic and dynamic controller. Secondly, to address the state constraints, the barrier Lyapunov function is incorporated with the kinematic controller. To resolve the problem of input saturation, the auxiliary design system is utilized in the dynamic controller. To address the problem of “explosion of complexity” inherent in the conventional back-stepping method, a nonlinear tracking differentiator is utilized to obtain the derivative of the desired yaw speed. Finally, the results of numerical simulation are performed to demonstrate the effectiveness of the proposed controller.

Optimal reduced frequency for the power efficiency of a flat plate gliding with spanwise oscillations

The spanwise oscillation provides an accessory or alternative to flapping motion toward high-efficiency bio-inspired flight. The power factor that measures the efficiency of a gliding wing with spanwise oscillation to support a unit weight is investigated in this work. The gliding wing model consists of a rectangular flat plate that oscillates sinusoidally along the spanwise direction in a uniform upstream flow at a post-stall angle of attack. The unsteady flows and aerodynamic forces are obtained by numerically solving the incompressible Navier–Stokes equations at a Reynolds number of 300 (based on the uniform upstream velocity and the chord length). It is found that the spanwise oscillation can effectively enhance the power factor of the rectangular wing. The power factor under the optimal spanwise oscillation is 1.97 times as large as that without spanwise oscillation. Then, we introduce an effective reduced frequency by accounting for the effect of spanwise oscillation on the velocity encountered by the wing. The results show that the optimal effective reduced frequency locates in a narrow region from 0.47 to 0.56. Finally, the analyses of the vortex structures and the Lamb vector field indicate that the enhanced power factor results from the interaction between the stable leading-edge vortex and side-edge vortices associated with the spanwise oscillation. This work is expected to be helpful in understanding the vortex dynamics and guiding the kinematic design of the high-efficiency bio-inspired flight with spanwise oscillation.

Kinematic Design of Rice Seed Planting Tool Using Four Bars Linkage Mechanism

Kinematics is the study of the relative motion of a component which includes the speed and acceleration of a machine without considering the causes of motion. The planting arm on the semi-mechanical rice seed planting tool works as a component of taking and planting rice into the soil. The planter arm is made using a four-bars linkage mechanism. The purpose of this research is to analyze the effect of kinematic parameters on the mechanism and to design the setting of planting depth by varying the length of the bars and calculating the speed and acceleration of the finger of the planter. The method used in this research is done analytically with GIM software application. The result of this research is the design of the dimensions of 4 bars linkage and the input value given to link 2 will affect the distance and depth of planting of rice using seed planting tool. Based on the dimensions and input values given, the planting depth is in the range of 83 mm so that it has met the required seedling planting criteria.

Design and Kinematics Analysis of Suspension System for a Formula Society of Automotive Engineers (FSAE) Car

The main objective of the Suspension of a vehicle is to maximize the contact between the vehicle tires and the road surface, provide steering stability and provide safe vehicle control in all conditions, evenly support the weight of the vehicle, transfer the loads to springs, and guaranteeing the comfort of the driver by absorbing and dampening shock. This paper discusses the kinematic design of a double a-arm Suspension system for an FSAE Vehicle. The hardpoint’s location can be determined using this procedure to simulate motion in any kinematic simulation software. Here, Optimum Kinematics is used as kinematic simulation software, and the results are verified using Msc Adams simulation. The method illustrated deals with the basics of Kinematics which helps to predict the characteristics of the Suspension even before simulating it in the kinematic simulation software.

Design and Implementation of Inverse Kinematics and Motion Monitoring System for 6DoF Platform

Six-axis motion platforms have a low contraction height and a high degree of freedom. First of all, the designed six-axis crank arm platform, including the motor, reducer, crank arm, link, platform support arm, and upper and lower platforms, can be designed for different bearing requirements. Secondly, it uses a coordinate transform and kinematics theory to derive each motor rotor angle. A set of platform data acquisition (DAQ) monitoring modules was established, and the LabVIEW programming language was used to write measurement software. The monitoring items include displacement, speed, and acceleration, which can be displayed on the screen and recorded by an industrial computer in real time and dynamically. Then, an RS-485 or RS-232 communication transmission interface was used to provide the control system with the related movement information. Finally, an industrial computer combined with a motion control card was used as a control kernel to realize the control algorithms, internet module function, I/O write and read signals, firmware integration, and human–machine interface message. The experimental results validate the appropriateness of the proposed method.

Beneficial wake-capture effect for forward propulsion with a restrained wing-pitch motion of a butterfly.

Unlike other insects, a butterfly uses a small amplitude of the wing-pitch motion for flight. From an analysis of the dynamics of real flying butterflies, we show that the restrained amplitude of the wing-pitch motion enhances the wake-capture effect so as to enhance forward propulsion. A numerical simulation refined with experimental data shows that, for a small amplitude of the wing-pitch motion, the shed vortex generated in the downstroke induces air in the wake region to flow towards the wings. This condition enables a butterfly to capture an induced flow and to acquire an additional forward propulsion, which accounts for more than 47% of the thrust generation. When the amplitude of the wing-pitch motion exceeds 45°, the flow induced by the shed vortex drifts away from the wings; it attenuates the wake-capture effect and causes the butterfly to lose a part of its forward propulsion. Our results provide one essential aerodynamic feature for a butterfly to adopt a small amplitude of the wing-pitch motion to enhance the wake-capture effect and forward propulsion. This work clarifies the variation of the flow field correlated with the wing-pitch motion, which is useful in the design of wing kinematics of a micro-aerial vehicle.

Performance augmentation mechanism of tandem flapping foils with stroke time-asymmetry

The performance augmentation mechanism of a tandem-foil system undergoing time-asymmetric flapping with unequal up- and downstroke durations (velocities) is investigated at three different phase angles, 0°, 90°, and 180°. Specifically, an asymmetry ratio, ranging from 0 to 0.4, is introduced to quantify the degree of the stroke time-asymmetry and to serve as the primary kinematic parameter of interest that affects the foil performances. Numerical simulations are implemented to predict the force production and to investigate the associated mechanism at different asymmetry ratios and phase angles. Validations are performed using digital particle image velocimetry in water tunnel experiments with two identical 3D printed wings. The results suggest that the foil performances at proper phase angles can be enhanced by stroke time-asymmetry. The force production during in-phase flapping obtains 15% increment while that during counterstroke flapping achieves remarkable enhancements by 2.5 times, as the asymmetry ratio increases from 0 to 0.4. The study also demonstrates that such enhancements are achieved through the changes in foil flapping velocities and foil-vortex interactions between the unequal up- and downstrokes. These findings not only provide insights toward the characteristics of tandem foils which are operated in non-sinusoidal flapping strokes but also offer a reference to the design of efficient wing kinematics for high-performance biomimetic propulsors.

Vision-Based Control of a Mobile Manipulator With an Adaptable-Passive Suspension for Unstructured Environments

Abstract The kinematic design, development, and navigation control of a new autonomous mobile manipulator for unstructured terrain is presented in this work. An innovative suspension system is designed based on the kinematic synthesis of an adaptable, passive mechanism. This novel suspension can compensate for irregularities in the terrain by using two pairs of bogies joined by a crank-slider mechanism and facilitates the control of the robotic platform using video cameras. The mobile robot is also equipped with a robotic manipulator, of which a synthesis, simulation, and experimental validation are presented. Additionally, manipulation is accomplished during motion on rough terrain. The proposed mobile robot has been fabricated using additive manufacturing (AM) techniques. A vision-based control approach, from here on named mobile linear-camera space manipulation (MLCSM), for mobile manipulators has been synthesized and implemented to conduct experimental tests. This mobile manipulator has been designed to traverse uneven terrain so that the loading platform is kept close to horizontal while crossing obstacles up to one-third of the size of its wheels. This feature allows for the onboard cameras to stay oriented toward the target; it also allows for any device mounted on the payload platform to remain nearly horizontal during the task. The developed control approach allows us to estimate the position and orientation of the manipulator’s end effector and update its trajectory along the path toward the target. The experiments show a final precision for engagement of a pallet within +/−2.5 mm in position and +/−2 deg in orientation

Effects of Root Canal Curvature and Mechanical Properties of Nickel-Titanium Files on Torque Generation

IntroductionThis study aimed to compare the torque generated by 4 different files in root canals with 4 different curvature angles. MethodsFour brands of nickel-titanium (NiTi) endodontic files were selected: WaveOne Primary (Dentsply Sirona, Ballaigues, Switzerland), WaveOne Gold Primary (Dentsply Sirona), ProTaper Universal F2 (Dentsply Sirona), and ProTaper Next X2 (Dentsply Sirona). A tempered steel block containing artificial canals with 4 different canal curvatures (15°, 25°, 35°, and 45°) was constructed. Each file was used according to the manufacturer’s instructions in the dynamic model, with an added 15 axial up-and-down movements of 4 mm at the end of the canal. The generated torque was recorded, and the total and maximum torque values were measured. Two-way analysis of variance and the Duncan post hoc comparison test were performed at a significance level of 95%. ResultsA significant correlation between the curvature angle and the type of file system was observed (P < .05). As the degree of canal curvature increased, the generated total and maximum torque increased. At 15° and 25°, the NiTi files with reciprocating motion generated a higher total and maximum torque than files with continuous rotation. ProTaper Universal of conventional NiTi alloy showed the steepest increase in the generated total and maximum torque with the increasing curvature angle. The ProTaper Next file had the lowest torque values at the higher canal angles of 35° and 45° (P < .05). ConclusionsDespite the study limitations, it can be concluded that root canal curvature, design, and heat treatment of NiTi files and file kinematics affect the generated torque during instrumentation.

Analysis of the space debris objects nozzle capture dynamic processed by a telescopic robotic arm

The paper considers a new layout of a two-stage spacecraft designed to remove a group of large space debris objects such as the upper stages of ‘Zenit’ launch vehicles from low-earth orbit. The aim of the work is to preliminarily quantify the parameters of the shock-absorbing system of the robotic arm designed for capturing a redundant upper stage by the main rocket engine nozzle. The estimation will be conducted by means of numerical simulation of the motion dynamics of the "spacecraft - space debris object" system. The paper presents the results of calculating the transient mode of oscillations of objects connected by the manipulator using simplified and detailed dynamic models of parameters, the analysis of the placement options for the manipulator shock-absorbing system, the analysis of the load reduction possibility through the use of attitude control thrusters, the analysis of two dynamic design variants of the mechanism for grabbing the critical section of the nozzle, and analysis of the capture dynamics at different initial angular velocities of rotation of a space debris object. The most rational shock-absorbing solution for a robotic arm with two translational and two rotary dampers is found. It is shown that the dynamic design of the nozzle capture mechanism has the greatest effect on the robotic arm loading. The kinematic design of the gripper selected as a result of the simulation almost completely eliminates shock loads in the process of damping the system vibrations. It is shown that the robotic arm shock-absorbing design has a significant margin for the initial angular velocity of the space debris object.

Kinematic Design of Functional Nanoscale Mechanisms From Molecular Primitives

Abstract Natural nanomechanisms such as capillaries, neurotransmitters, and ion channels play a vital role in the living systems. But the design principles developed by nature through evolution are not well understood and, hence, not applicable to engineered nanomachines. Thus, the design of nanoscale mechanisms with prescribed functions remains a challenge. Here, we present a systematic approach based on established kinematics techniques to designing, analyzing, and controlling manufacturable nanomachines with prescribed mobility and function built from a finite but extendable number of available "molecular primitives." Our framework allows the systematic exploration of the design space of irreducibly simple nanomachines, built with prescribed motion specification by combining available nanocomponents into systems having constrained, and consequently controllable motions. We show that the proposed framework has allowed us to discover and verify a molecule in the form of a seven link, seven revolute (7R) close loop spatial linkage with mobility (degree of freedom) of one. Furthermore, our experiments exhibit the type and range of motion predicted by our simulations. Enhancing such a structure into functional nanomechanisms by exploiting and controlling their motions individually or as part of an ensemble could galvanize development of the multitude of engineering, scientific, medical, and consumer applications that can benefit from engineered nanomachines.

Kinematic design of a translational parallel mechanism based on sub-kinematic chain determined workspace superposition

This paper presents the kinematic design of a translational parallel mechanism (PM) named Vari-Orthoglide by means of the workspace superposition, according to the sub-kinematic chain (SKC) based PM composition principle. The main topological characteristics of the manipulator with two SKCs under study, such as the position and orientation (POC) characteristics, degree of freedom (DOF) and coupling degree are analyzed, which turns out that the coupling degree equals to 1, implying the partially decoupled motion. With the topological characteristics based kinematic modeling principle, a symbolic model of the kinematics is established to derive its symbolic direct and inverse kinematic solutions. Based upon the direct kinematic solution, the workspaces for the two SKCs can be efficiently found. Moreover, the singularity loci are identified for finding the singularity-free workspace, where a regular workspace is fitted as the task workspace as expected. The presented work shows an approach to design translational parallel mechanisms considering motion decoupling and regular workspace, applicable to other types of parallel mechanisms.

Tension management in cable transmission systems for remote manipulators

This paper presents the design of a novel kinematic tensioning system to remedy the situation where the input-output relation in the cable transmission for a remotely operated multi-link end-effector is compromised due to the onset of slack. The actuation of multi-link end-effectors in remote manipulators via cable transmission exhibits loss of tension and slack generation on the non-driving side of the cable transmission. This paper outlines an analytical formulation of the kinematic component of slack resulting from the geometry of the end-effector links that are serially connected. If left unaddressed, cable slack adversely impacts transmission stiffness and produces backlash at the end-effector wherein for a fixed input, the output can move freely over a range of motion (i.e. dead-band). In case of articulating instruments for minimally invasive surgery, this limits the ability to position and orient the end-effector precisely, the ability to effectively transmit forces via the end-effectors to the surrounding tissues, and the tactile feedback to the user operating the instrument. To overcome these limitations, this paper presents a simple solution that effectively mitigates slack on the non-driving side of a cable transmission between a driving pulley and a multi-link end-effector with minimal cost or complexity. The proposed design uses a driving pulley modified with tensioner extensions to alter the transmission path, which provides a kinematic or geometric solution in contrast to the various spring based solutions that have several drawbacks. Based on a derivation of slack in the system, a design optimization is performed to generate the key dimensions of the tensioning system that minimizes slack without causing over-constraint. An experimental setup is designed and fabricated to validate the slack predictions in the cable transmission system for a multi-link end-effector, without and with the proposed tensioner. The experimental measurements demonstrate the efficacy of the proposed solution.

Kinematic Analysis and Optimal Design of a Novel Schönflies-Motion Parallel Manipulator With Rotational Pitch Motion for Assembly Operations

Abstract This paper presents a novel Schönflies-motion Parallel Manipulator with RotationalPitch motion (SPM-RP) based on a single-platform fully parallel mechanism. An analysis of the position, workspace, velocity, and singularity of the SPM-RP is carried out in detail, and a dimensionless Jacobian is proposed to evaluate the manipulability of the SPM-RP. The analysis shows that the SPM-RP is with position-decoupled kinematics, a large singularity-free workspace, and excellent manipulability. The SPM-RP is actuated by four parallel prismatic actuators, enabling the manipulator to provide the identical kinematic performance at all generic cross sections perpendicular to the prismatic joint axes within its workspace. This paper thus proposes a reduced design optimization formulation, where the traditional optimization over the entire workspace is reduced to the optimization on a representative workspace cross section of the SPM-RP. According to this approach, the design optimization of the SPM-RP is carried out by maximizing its manipulability over the total orientation workspace, which is crucial for precision assembly. Based on the achieved optimal design, an SPM-RP prototype is developed. The mobility, orientation capability, total orientation workspace, and repeatability of the optimal design are tested and verified by the developed SPM-RP prototype. Experiments show that the SPM-RP can achieve a large total orientation workspace with excellent precision performance.

Mathematical model-based redesign of chickpea harvester reel

Aim of study: This paper presents a mathematical modeling approach to redesign the reels of chickpea harvesters for harvest efficiency.Area of study: A prototype chickpea harvester was designed and evaluated on the Dooshan farm of the University of Kurdistan, Sanandaj, Iran.Material and methods: The strategy used for reducing harvesting losses derived from the dynamic study of the reel applied to the chickpea harvester. The machine was designed such that bats of a power take-off (PTO)-powered reel, in conjunction with passive fingers, harvest pods from anchored plants and throw the pods into a hopper. The trochoid trajectory of the reel bats concerning reel kinematic index, and plant height and spacing was determined for redesigning the reel.Main results: This kinematic design allowed an estimation of the reel orientation at the time of impact. The experimentally validated model offers an accurate and low computational cost method to redesign harvester reels.Research highlights: The new chickpea harvester implemented with a four fixed-bat reel, a height of 40 cm above the ground for the reel axis, and featuring a kinematic index of 2.4 was capable of harvesting pods with harvesting efficiency of over 70%; a significant improvement in harvesting performance.

Workspace analysis of 3-DOF U-shape base planar parallel robotic motion stage using shape memory alloy restoration technique (SMART) linear actuators

The applications of lightweight planar parallel robotic manipulators are increasing enormously because of its various desirable characteristics such as low weight, lower inertia and higher stiffness. Higher accelerations and accuracies can be achieved in planar parallel manipulators. Also, shape memory alloy restoration technique (SMART)-based linear actuators are replacing huge and bulky linear actuators. This study presents the kinematic design of smart linearly actuated family of U-shape base planar parallel robotic manipulator. With the aid of solid modelling software, different available configurations were modelled and their workspace was analysed. The developed 3-DOF motion stages (18 unique configurations) were fabricated using fused deposition modelling process, and the top three configurations having higher workspace were further experimented. It is interesting to observe that the actual or experimental workspace of a particular manipulator configuration is further minimised from the predicted or feasible workspace. It is due to the presence of passive links, singularities, friction between the parts, heat dissipation, force distribution, stiffness, etc. The present study depicts the experimental workspace of the top three configurations, namely PPR-PRP-PRR, PRP-PPR-PRP and PRP-PPR-PRR. Since none of the experimental workspace observed is equal or higher than the model workspace, an efficiency loss in terms of workspace reduction was calculated to understand the acceptability of the configurations in different domains. Apart from the loss, the result disclosed that the actual workspace of all the manipulators was within the feasible workspace domain of mobile platform. The PPR-PRP-PRR manipulator was found to possess highest experimental workspace than other configurations. Note: P, P, and R refer to active prismatic, passive prismatic and passive revolute joints respectively.

Serial-kinematic monolithic nanopositioner with in-plane bender actuators

This article describes a monolithic nanopositioner constructed from in-plane bending actuators which provide greater deflection than previously reported extension actuators, at the expense of stiffness and resonance frequency. The proposed actuators are demonstrated by constructing an XY nanopositioning stage with a serial kinematic design. Analytical modeling and finite-element-analysis accurately predicts the experimental performance of the nanopositioner. A 10μm range is achieved in the X and Y axes with an applied voltage of +/-200 V. The first resonance mode occurs at 250 Hz in the Z axis. The stage is demonstrated for atomic force microscopy imaging.

Quality Function Deployment and Design Risk Analysis for the Selection and Improvement of FDM 3D Printer

Currently, the use of additive technologies is becoming relevant instead of traditional production technologies. The market offers a fairly large selection of 3D printers with different designs and kinematics. Each design and kinematics has its own disadvantages and advantages. The article demonstrates various versions of the kinematics of FDM 3D printers, the main units and parts, as well as their impact on the quality of 3D printing of parts. The results of structuring the quality function (QFD) and analysis of the types and consequences of potential inconsistencies (FMEA) of an FDM 3D printer for prototyping and manufacturing parts and assemblies for unmanned aerial vehicles are presented. A qualimetric assessment of the quality of FDM 3D printers with various kinematics design based on the QFD interconnection matrix was carried out. The aim of the study is to analyze the design and kinematics of FDM 3D printers for the manufacture of high-quality parts and assemblies for unmanned aerial vehicles without further post-processing based on the application of the QFD methodology. Based on the results of the study, recommendations and proposals for improving the design of FDM 3D printers were developed.

Inverse Kinematics Data Adaptation to Non-Standard Modular Robotic Arm Consisting of Unique Rotational Modules

The paper describes the original robotic arm designed by our team kinematic design consisting of universal rotational modules (URM). The philosophy of modularity plays quite an important role when it comes to this mechanism since the individual modules will be the building blocks of the entire robotic arm. This is a serial kinematic chain with six degrees of freedom of unlimited rotation. It was modeled in three different environments to obtain the necessary visualizations, data, measurements, structural changes measurements and structural changes. In the environment of the CoppeliaSim Edu, it was constructed mainly to obtain the joints coordinates matching the description of a certain spatial trajectory with an option to test the software potential in future inverse task calculations. In Matlab, the model was constructed to check the mathematical equations in the area of kinematics, the model’s simulations of movements, and to test the numerical calculations of the inverse kinematics. Since the equipment at hand is subject to constant development, its model can also be found in SolidWorks. Thus, the model’s existence in those three environments has enabled us to compare the data and check the models’ structural designs. In Matlab and SolidWorks, we worked with the data imported on joints coordinates, necessitating overcoming certain problems related to calculations of the inverse kinematics. The objective was to compare the results, especially in terms of the position kinematics in Matlab and SolidWorks, provided the initial joint coordinate vector was the same.