First integrals of the system “platform with pendulum” and controlling of it

The problem of controlling the movement of a movable platform with a hinged fixed pendulum is considered. This pair is interpreted as a system of stationary connected points one of which moves freely in a horizontal plane. In the first problem, a control is synthesized that ensures the movement of the platform in a limited area under any initial conditions. In the second problem, a control is synthesized that stabilizes the oscillations of the pendulum in a given fixed vertical plane relative to the suspension point. For the problem of control synthesis, the first integrals of a free system are found and used in the article.

INFLUENCE OF PERIODIC MODERATE LINEAR ACCELERATIONS OF VARIABLE DIRECTION ON CENTRAL HEMODYNAMICS

It was examined 19 male fencers aged 18 to 24 years , who had sports experience from 8 to 14 years and high sports qualifications in the chosen sport (masters of sports and candidates for masters of sports). Subjects had no significant differences in height and body weight. Linear horizontal accelerations were created using a movable platform with a chair, which housed the athlete. Passive movement of fencers on the platform corresponded to their usual parameters of movement on the fencing track during a sports match. It has been shown that the short-term effect of horizontal moderate accelerations of the variable direction when using the functional test (FT) led to small but statistically significant changes in heart rate (HR), stroke volume (SV) and volumetric blood ejection rate (VER). In all subjects, the changes in these indicators after FT were as follows: heart rate decreased slightly, and SV and VER increased. FT revealed that in persons who are accustomed to moving with moderate horizontal linear accelerations of variable direction, the shortterm effect of this factor was accompanied by a tendency to decrease the minute volume of blood flow (MVB) due to decreased of heart rate. Increasing of SV and VER can be considered as an immediate compensatory response aimed at maintaining MVB. Thus, in athletes whose long-term sports activities are associated with the action on the body of periodic moderate horizontal linear accelerations of variable direction, no adaptation to the action of this specified factor is formed.

A Research Study to Increase Usage of PVs in Residential Areas

Self-generation of energy by residential houses has been met with many obstacles. When PV Solar energy technology is considered, the barriers manifest in problems related to the location, slope, strength, and shade exposure of house roofs are the most common. Therefore, it is not possible to meet daily energy needs from PV panels placed on the existing roofs of many houses. Solar Tracking Systems keep PV panels perpendicular to the Sun throughout the day, providing a significant increase in their efficiency. But the application of these systems on the roofs or houses is not suitable for many reasons, especially in terms of aesthetic appearance. This article is aimed at effectively showing how the slope and direction inconsistencies in the existing roofs of houses in residential areas cause great losses in the performance of PVs; also a research and design study is presented to find a solution to the application of Sun tracking systems in residential areas without creating aesthetic appearance problem. As a solution, combining a dual axis Sun tracking system with an aesthetic looking Gazebo has been considered. A design study was carried out for the targeted system, and the dimensions of a movable platform/roof such a system should have in order to meet the electricity needs of a house from the Sun throughout the year was investigated. How much energy the PV panels can collect annually is determined by a simulation program called “PV performance tool”.

Study of the effects of link tolerances to estimate mechanical errors in 3-RRS parallel manipulator

This paper presents the mechanical error estimation under the effects of link tolerances in a 3-degree-of-freedom (DoF) 3-RRS Spatial Parallel Manipulator (SPM). Position level kinematic analysis and workspace analysis in the form of reachable and orientation workspace are carried out initially. Then, the effect of link tolerances on individual link is studied at the position of mid-point and orientation of the movable platform. The corresponding mechanical errors are estimated. The effect of link tolerance variation is studied to know the pattern of mechanical error. The 3-D CAD model in SolidWorks is used to validate the results. The conclusions are drawn that lead to error minimization at the tolerance design stage.

Development of a control architecture for a parallel three-axis robotic arm mechanism using CANopen communication protocol

Based upon the CANopen communication protocol and the LabVIEW graphic programing procedures, this paper develops a closed-loop control architecture for a parallel three-axis (Delta) robotic arm mechanism. The accomplishments include prototyping a parallel three-axis robotic arm mechanism, assembling servomotors with associated encoders and gearsets, coding CANopen communication scripts for servomotor controllers and a host supervision GUI, coding forward/inverse kinematics scripts to compute the required servomotor rotations and the coordinates of a movable platform or the mechanism, coding tracking error compensation scripts for effective closed-loop griper control, and coding integration scripts to command and supervise the mechanism motion on the LabVIEW-based host GUI. During the development stage, this research designed and prototyped the parallel three-axis robotic arm mechanism based upon basic Delta robot kinematics. To control the mechanism effectively and accurately, this study implemented the CANopen communication protocol, which characterizes high speed and stable transmission. The protocol applies to the CANopen communication channels among the controllers and the host supervision GUI. On the LabVIEW development platform, the coded supervision GUI performs issuing/receiving messages to the CANopen-based controllers. The controllers excite the servomotors and actuate the parallel mechanism to track prescribed trajectories in a closed-loop control fashion. Meanwhile, an electromagnet attached to the movable platform of the robotic mechanism performs satisfactory picking/placing object actions.

Fall inducing movable platform (FIMP) for overground trips and slips

Background The study of falls and fall prevention/intervention devices requires the recording of true falls incidence. However, true falls are rare, random, and difficult to collect in real world settings. A system capable of producing falls in an ecologically valid manner will be very helpful in collecting the data necessary to advance our understanding of the neuro and musculoskeletal mechanisms underpinning real-world falls events. Methods A fall inducing movable platform (FIMP) was designed to arrest or accelerate a subject’s ankle to induce a trip or slip. The ankle was arrested posteriorly with an electromagnetic brake and accelerated anteriorly with a motor. A power spring was connected in series between the ankle and the brake/motor to allow freedom of movement (system transparency) when a fall is not being induced. A gait phase detection algorithm was also created to enable precise activation of the fall inducing mechanisms. Statistical Parametric Mapping (SPM1D) and one-way repeated measure ANOVA were used to evaluate the ability of the FIMP to induce a trip or slip. Results During FIMP induced trips, the brake activates at the terminal swing or mid swing gait phase to induce the lowering or skipping strategies, respectively. For the lowering strategy, the characteristic leg lowering and subsequent contralateral leg swing was seen in all subjects. Likewise, for the skipping strategy, all subjects skipped forward on the perturbed leg. Slip was induced by FIMP by using a motor to impart unwanted forward acceleration to the ankle with the help of friction-reducing ground sliding sheets. Joint stiffening was observed during the slips, and subjects universally adopted the surfing strategy after the initial slip. Conclusion The results indicate that FIMP can induce ecologically valid falls under controlled laboratory conditions. The use of SPM1D in conjunction with FIMP allows for the time varying statistical quantification of trip and slip reactive kinematics events. With future research, fall recovery anomalies in subjects can now also be systematically evaluated through the assessment of other neuromuscular variables such as joint forces, muscle activation and muscle forces.

Welding of pins to mobile platforms arms

There is an increasing demand for mixed joints made of hard-weldable steels used in the construction of transport means. An illustration of this is the welding of movable platform elements such as a pin to arm joints. The pin is made of high-strength structural steel S690 QL (1.8928) while the arm of the movable platform is made of DOCOL 1200M steel from the AHSS group (Advanced High-Strength Steel). Such a joint is not easy to make due to the different chemical composition of both steels. The difference in thickness of welded elements creates an additional difficulty. The thickness of the cylindrical pin is 40 mm, whereas the thickness of the sheet metal used for the platform arm is much smaller and amounts to 2 mm. Joints of varying thickness and chemical composition tend to produce cracks in the heat-affected zone as well as in the weld. The purpose of this article is to determine the most appropriate welding parameters and the selection of additional materials to obtain correct joint with good mechanical properties, free of welding defects and incompatibilities.

Fall Inducing Movable Platform (FIMP) for Overground Trips and Slips

Background: The study of falls and fall prevention/intervention devices requires the recording of true fallsincidence. However, true falls are rare, random, and difficult to collect in real world settings. A system capableof producing falls in an ecologically valid manner will be very helpful in collecting the data necessary toadvance our understanding of the neuro and musculoskeletal mechanisms underpinning real-world falls events.Methods: A fall inducing movable platform (FIMP) was designed to arrest or accelerate a subject's ankle toinduce a trip or slip. The ankle was arrested posteriorly with an electromagnetic brake and acceleratedanteriorly with a motor. A power spring was connected in series between the ankle and the brake/motor toallow freedom of movement (system transparency) when a fall is not being induced. A gait phase detectionalgorithm was also created to enable precise activation of the fall inducing mechanisms. Statistical ParametricMapping (SPM1D) and one-way repeated measure ANOVA were used to evaluate the ability of the FIMP toinduce a trip or slip.Results: During FIMP induced trips, the brake activates at the terminal swing or mid swing gait phase toinduce the lowering or skipping strategies, respectively. For the lowering strategy, the characteristic leg loweringand subsequent contralateral leg swing was seen in all subjects. Likewise, for the skipping strategy, all subjectsskipped forward on the perturbed leg.Slip was induced by FIMP by using a motor to impart unwanted forward acceleration to the ankle with thehelp of friction-reducing ground sliding sheets. Joint stiffening was observed during the slips, and subjectsuniversally adopted the surfing strategy after the initial slip.Conclusion: The results indicate that FIMP can induce ecologically valid falls under controlled laboratoryconditions. The use of SPM1D in conjunction with FIMP allows for the time varying statistical quanticationof trip and slip reactive kinematics events. With future research, fall recovery anomalies in subjects can nowalso be systematically evaluated through the assessment of other neuromuscular variables such as joint forces,muscle activation and muscle forces.

Welding supports of fine-grained steel mobile platforms

The article presents the process of welding of steel movable platform supports. There is a growing demand for the welding of difficult-to-weld fine grain steels used in civil engineering and transport. An example of this could be the use of high-strength movable platform supports. The recently used material in the production of movable platform supports are fine-grained steels due to their high tensile strength of 1000 MPa. The joints formed using them, however, are characterized by much lower strength than the native material. In this article, the most appropriate parameters were selected for welding the movable platform supports made of difficult-to-weld fine-grained steel S960 MC.