146 research outputs found
Parallel Robot for Lower Limb Rehabilitation Exercises
Full text linkThe aim of this study is to investigate the capability of a 6-DoF parallel robot to perform various rehabilitation exercises. The foot trajectories of twenty healthy participants have been measured by a Vicon system during the performing of four different exercises. Based on the kinematics and dynamics of a parallel robot, a MATLAB program was developed in order to calculate the length of the actuators, the actuators' forces, workspace, and singularity locus of the robot during the performing of the exercises. The calculated length of the actuators and the actuators' forces were used by motion analysis in SolidWorks in order to simulate different foot trajectories by the CAD model of the robot. A physical parallel robot prototype was built in order to simulate and execute the foot trajectories of the participants. Kinect camera was used to track the motion of the leg's model placed on the robot. The results demonstrate the robot's capability to perform a full range of various rehabilitation exercises
Application of a parallel robot in lower limb rehabilitation: A brief capability study
No full textRobotic rehabilitation has a significant potential to reduce the clinical labor costs of physiotherapy. Robotic therapy allows patients to have more in-depth repetitive movements while the therapists evaluate the progress of the recovery. This paper investigates the potential of a 6 degrees of freedom parallel robot, designed and built at the University of Birmingham, for use in robotic rehabilitation of stroke patients. The foot trajectories of eight post-stroke patients were recorded and analyzed in a gait laboratory. A graphical user interface (GUI) has been designed, which enables the physiotherapist to select the desired exercise from a dedicated database. Three different rehabilitation exercises were investigated: hip flexion/extension, ankle dorsiflexion /plantarflexion, and marching. The results show that the robot was able to repeat all of these foot trajectories successfully, while being able to lift 200kg load in its dynamic mode. This suggests that the robot has the capability to successfully deliver lower limb rehabilitation exercises.</p
Path's slicing analysis as a therapist's intervention tool for robotic rehabilitation
No full textThe assisted limb rehabilitation process is commonly associated with advanced control of the affected limb through robotic assistance and human interference. The robotic element is only expected to be able to reproduce the motion suitable for large variations of patient’s condition within a reasonable accuracy and stiffness. Therapist’s intervention of fine-control is in the format of planar elements (like pelvis linkage) or joints (like knee), which relate to trajectory or orientation adjustments. The rehabilitation process has to consider the patient’s ability, limit and motion constraint that form those two factors. The parameters for controlling these is associated with kinematic, that defines the behaviour and characteristic of the lower limb. The developed 3D Python simulation system allows for this fine-tuning in the form of slice analysis and interval analysis. The results show that Bezier could be successfully used in various development aspects of parallel robots. The Hybrid and Hexapod robot configurations in this study can then be linked to a Haptic controller that runs on Python’s Haptic engine.</p
Path-planning of a hybrid parallel robot using stiffness and workspace for foot rehabilitation
Full text linkStiffness is one of the important parameters for estimating the performance of hybrid parallel robots as it is not constant throughout its workspace. The aim of this study is to provide an optimum path based on maximum stiffness within the workspace of a 9-degree-of-freedom hybrid parallel mechanism configuration, which includes nine linear actuators connecting one stationary and two moving platforms in series. The proposed robot is designed for ankle rehabilitation, where accurate and precise movement of lower extremities is required. The design takes advantage of two important characteristics of parallel robots: stiffness and workspace. The proposed methodology to determine the stiffness of hybrid robot in three single axes is based on calculation of position vector of each actuator in any particular pose, by considering the inverse kinematics of the system, in order to obtain the magnitude and direction of the applied forces. The results obtained from the workspace calculations have been compared with those of two standard parallel mechanisms including a 6-degree-of-freedom hexapod and a tripod with 3 degrees of freedom. The stiffness of the robot has been calculated in simulation and then compared with those of a developed prototype hybrid model in two different case studies
The cost of flexibility
Full text linkPurpose - In the automobile industry, the variety of vehicles produced continues to increase. At the same time, historically firms have incurred a sizeable productivity penalty for producing more variety in their plants. The purpose of this paper is to answer the question: what actions have firms taken to control this productivity penalty and what were the costs? Design/methodology/approach - Estimate a number of statistical models of the effect of variety on productivity for a sample that includes almost all assembly plants in North America from 1994 to 2004. Findings - Evidence is found for fixed costs associated with activities that are complementary to producing variety and for a trade-off between scale economies and flexibility. Research limitations/implications - Provides evidence that while flexibility has an advantage to cope with increasing variety, there are non-negligible costs as well. Originality/value - A first systematic evaluation on the scale-scope trade-off and a quantification of the gains from production flexibility in the automotive industry.status: Publishe
Versatile Microfluidics for Biofabrication Platforms Enabled by an Agile and Inexpensive Fabrication Pipeline
Full text linkMicrofluidics have transformed diagnosis and screening in regenerative medicine. Recently, they are showing much promise in biofabrication. However, their adoption is inhibited by costly and drawn‐out lithographic processes thus limiting progress. Here, multi‐material fibers with complex core‐shell geometries with sizes matching those of human arteries and arterioles are fabricated employing versatile microfluidic devices produced using an agile and inexpensive manufacturing pipeline. The pipeline consists of material extrusion additive manufacturing with an innovative continuously varied extrusion (CONVEX) approach to produce microfluidics with complex seamless geometries including, novel variable‐width zigzag (V‐zigzag) mixers with channel widths ranging from 100–400 µm and hydrodynamic flow‐focusing components. The microfluidic systems facilitated rapid mixing of fluids by decelerating the fluids at specific zones to allow for increased diffusion across the interfaces. Better mixing even at high flow rates (100−1000 µL min−1) whilst avoiding turbulence led to high cell cytocompatibility (>86%) even when 100 µm nozzles are used. The presented 3D‐printed microfluidic system is versatile, simple and efficient, offering a great potential to significantly advance the microfluidic platform in regenerative medicine
Kinematic performance enhancement of wheelchair-mounted robotic arm by adding a linear drive
No full textWheelchair-Mounted Robotic Arms have been used to help impaired people to reach objects and perform essential activities in an autonomous way. Different available models are presented in this paper and a simple design is proposed to improve the kinematic performances of the integrated system in order to allow the user to increase its capability of interaction with home environment. To this end, a linear drive has been added to the Raptor model in order to move along the wheelchair. The benefit of the proposed development has been proved with a kinematic performance assessment procedure, which has analyzed critical points in the 3D space, providing 26% increase in performance with respect to the existing solution.</p
Research on the effects of different masses of ammonium nitrate fertilizer on growth of Phaseolus vulgaris
Full text linkGlobal warming has recently become one of the biggest threats that the world faces.
The importance of fertile lands and water sources are constantly increasing. Many researches
are done to get more qualified crops and different solutions are found. Fertilizers are one of
those solutions. Ammonium nitrate (AN) is a type of chemical fertilizers and it increases the
rate of the growth of the plants. Different masses of AN cause different effects on plants.
Therefore, it must be given in an optimum ratio. The objective of this study is to investigate
whether different masses of AN fertilizer used is effective on the growth of the Phaseolus
vulgaris. During the experiment, proportionally increasing masses of AN is mixed to the soil
that common beans are planted in. Four groups are developed; control group containing no
fertilizer, experimental group 1 containing 0.42 g AN, experimental group 2 containing 0.84
g AN and the last group, experimental group 3 containing 1.26 g AN. The plants are irrigated
daily and observed for 1.5 months in order to see the effects of different masses of AN by
taking measurements of the stem length, number of offsprings produced and observing the
color of leaves.
The results showed that there comes a significant difference if the mass of fertilizer
used is changed. As the mass of AN used increases, the growth rate increases; however the
excess mass of AN causes deficiency in some essential elements for the plant and reduces root
growth
Efficient Observer Design for Ambulatory Estimation of Body Centre of Mass Position
Full text linkComplementary Linear Filter (CLF) is a common techinque employed for estimating the ground projection of body Centre of Mass starting from ground reaction forces. This method fuses centre of pressure position and double integration of horizontal forces, selecting best cut-off frequencies for low-pass and high-pass filters. Classical Kalman filter is a substantially equivalent approach, as both methods rely on an overall quantification of error/noise and don't analyze its origin and time-dependence. In order to overcome such limitations, a Time-Varying Kalman Filter (TVKF) is proposed in this paper: the effect of unknown variables is directly taken into account by employing a statistical description which is obtained from experimental data. To this end, in this paper we have employed a dataset of 8 walking healthy subjects: beside supplying gait cycles at different speeds, it deals with subjects in age of development and provides a wide range of body sizes, allowing therefore to assess the observers' behaviour under different conditions. The comparison carried out between CLF and TVKF appears to highlight several advantages of the latter method in terms of better average performance and smaller variability. Results presented in this paper suggest that a strategy which incorporates a statistical description of unknown variables and a time-varying structure can yield a more reliable observer. The demonstrated methodology sets a tool that can undergo a broader investigation to be carried out including more subjects and different walking styles.</p
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