Mathematical description of a hybrid quadrocopter for the purpose of computer simulation of controlled motion

The problem of constructing the most complete mathematical model of the movement of a hybrid-type quadcopter, which, in addition to electric motors, is also equipped with an internal combustion engine, is considered. The relevance of this development is due to the desire to create a control system for a quadcopter of relatively new design, and the feasibility of development is due to the desire to use integrated design, improving the design of the device and elements of navigation and control. The developed mathematical model of the motion of the center of mass of the quadcopter and around the center of mass includes control variables and takes into account the gyroscopic moments from the rotors of the engines - carriers of kinetic moments. This model can be used in the process of designing and debugging control algorithms for such aircraft. The main method of modeling is the numerical integration of the system of differential equations. The given modeling complex will allow to carry out researches on influence of perturbing factors and imperfection of elements of a control system; test and improve management laws; to modernize the design of the quadcopter to increase the efficiency of operation. The advantage of the model is its validity, openness, versatility, as it is easy to adapt to any other design of the quadcopter.

Two problems of movement of multi-link wheeled vehicles

The paper presents the results of a study of the dynamics of multi-link wheeled vehicles with nonholonomic connections superimposed on this mechanical system. The article is of an overview nature. The mathematical formulation is a system of ordinary differential equations of motion in the form of Lagrange with undefined multipliers, solved together with derivatives of nonholonomic constraints. The results are presented in the case of controlled motion, when the law of motion of the first link is known, as well as in the case of uncontrolled motion, when the law of motion of the leading link is also the desired function of time. General equations are obtained for a mechanical system consisting of an arbitrary number of links. Numerical results are presented for the case of three coupled trolleys. The software package Maple was used to perform numerical calculations and plotting of the desired mechanical parameters.

Development and Research of Motion Control Algorithms of Elastic Electromechanical Systems Taking into Account the Damping Properties of the Electric Drive

The paper presents the results of studies of the effect of the counter-electromotive force (CEMF) of the dc machine on the parameters of the elastic oscillation control system of a two-mass electromechanical system, synthesized based on of solving the inverse problems of dynamic in accord with prescribed nature of controlled motion. It is shown by the method of numerical simulation that taking into account the CEMF leads to an increase of the damping properties of the electromechanical system and an increase of the gains of the feedbacks on the force in the cable. A method for the selection of these gains is proposed, based on their comparison with the gains obtained in an electromechanical system without taking into account the CEMF and an approximate assessment of its effect on the nature of the transient processes.

Design and Analysis of the Spray-Painting Robot for tall statues and monuments

The painting on tall structures, statues, monuments and buildings is dangerous task for humans. Robotics finds its applications in operations, which are repetitive, hazardous, and dangerous. The aim of the present work is to design a manipulator for spray painting on surfaces of tall monuments, statues and structures. The robot can be installed on a crane platform for lifting and operated from the ground. A lightweight and compact design is desired that can be easily accommodated within the space of the crane. A Revolute-Revolute-Revolute-Prismatic (RRRP) type Robotic arm is developed and analysed for this application. By establishing the rigid body tree model in Robotics System Toolbox, the numerical model of direct and inverse kinematics using Homogenous Matrix Transformation is prepared in MATLAB. Using the spray patch method and offline programming method, the spray model is prepared in Solid woks to obtain trajectory waypoints. A B-spline path is generated through these waypoints. At each waypoint, joint displacement variables are calculated using an inverse kinematic model. An air-less spray gun is selected and attached with a robot. Controlled motion algorithm for spray painting operation on a circular surface were obtained with simulation results. A smooth trajectory for performing spray painting is obtained.

4D Thermomechanical metamaterials for soft microrobotics

Metamaterials have attracted wide scientific interest to break fundamental bounds on materials properties. Recently, the field has been extending to coupled physical phenomena where one physics acts as the driving force for another. Stimuli-responsive or 4D metamaterials have been demonstrated for thermo-elasticity, magneto-optics or piezo-electricity. Herein, a soft, ultra-compact and accurate microrobot is described which can achieve controlled motion under thermal stimuli. The system consists of an organized assembly of two functional structures: a rotational and a translational element. Both elements are designed basing upon the principle of the thermoelastic bilayer plate that bends as temperature changes. Samples are fabricated using gray-tone lithography from a single polymer but with two different laser writing powers, making each part different in its thermal and mechanical behaviors. Excellent motion-controllable, reversible and stable features in a dry environment are verified by simulations and experiments, revealing broad application prospects for the designed soft micro actuators.

Is Early Controlled Motion and Weightbearing Recommended for Nonoperatively Treated Acute Achilles Tendon Rupture? A Systematic Review and Meta-analysis

Background: There is disagreement as to whether early controlled motion and weightbearing confer a beneficial effect for nonoperatively treated acute Achilles tendon rupture (ATR) compared with immobilization and late weightbearing. Purpose: To conduct a meta-analysis of randomized controlled trials (RCTs) to determine whether early controlled motion and weightbearing results in different outcomes compared with immobilization and late weightbearing for nonoperatively treated patients with acute ATR. Study Design: Systematic review; Level of evidence, 1. Methods: We conducted a search in the PubMed, Web of Science, and EMBASE databases for relevant RCTs in humans from January 1981 to August 2020. The primary outcome was the Achilles Tendon Total Rupture Score (ATRS) at 1-year follow-up. The secondary outcomes were the rerupture rate, return to sports activity and work, and the heel-rise work (limb symmetry index [LSI]). Study quality was assessed using the Cochrane Collaboration risk of bias tool. Results: Included were 7 RCTs involving 424 participants (n = 215 treated with early controlled motion and weightbearing [early group], n = 209 treated with immobilization and late weightbearing [late group]). The quality assessment indicated a low risk of bias in all included RCTs. There was no difference between the early and late groups regarding the ATRS (mean difference [MD], -0.220; 95% CI, -4.489 to 4.049; P = .920). Likewise, we found no difference between the 2 groups in terms of the rerupture rate (odds ratio [OR], 1.107; 95% CI, 0.552 to 2.219; P = .775), the number of patients who returned to sports (OR, 0.766; 95% CI, 0.438 to 1.341; P = .351) and returned to work (OR, 0.706; 95% CI, 0.397 to 1.253; P = .234), the time to return to work (MD, -2.802 days; 95% CI, -6.525 to 0.921 days; P = .140), or the heel-rise work LSI (MD, -0.135; 95% CI, -6.243 to 5.973; P = .965). Conclusion: No significant differences were found between early controlled motion and weightbearing compared with immobilization and late weightbearing regarding the ATRS, the rerupture rate, return to sports activity and work, and the heel-rise work in nonoperatively treated patients with acute ATR.

Decentralized Control of Nanosatellite Tetrahedral Formation Flying Using Aerodynamic Forces

A decentralized control algorithm for the construction of a tetrahedral configuration using differential lift and drag forces is proposed in this paper. Four 3U CubeSats launched in LEO are considered. Satellite attitude-controlled motion relative to the incoming airflow provides the required differential forces in order to change the relative translational motion. The developed control algorithm allows one to track the relative reference trajectories for the satellites at the vertices of the tetrahedron of the required shape and size. The influence of the initial launch conditions on the controlled tetrahedral motion is studied in this paper.