Vol. 18, no. 5
Vol. 18, no. 5, 2022
Conference NIR2022
Marchuk E. A., Kalinin Y. V., Sidorova A. V., Maloletov A. V.
Abstract
This paper deals with the application of force sensors to estimate position errors of the center
of mass of the mobile platform of a cabledriven parallel robot. Conditions of deformations of
cables and towers of the robot are included in the numerical model and external disturbance is
included too. The method for estimating the error in positioning via force sensors is sensitive
to the magnitude of spatial oscillations of the mobile platform. To reduce torsional vibrations
of the mobile platform around the vertical axis, a dynamic damper has been included into the
system.

Shaker W. K., Klimchik A. S.
Abstract
This paper deals with the stiffness modeling of the double pantograph transmission system.
The main focus is on the comparison analysis of different stiffness modeling approaches: virtual
joint modeling (VJM) and matrix structural analysis (MSA). The aim of this work is to
investigate the limitations of the considered approaches. To address this issue, corresponding
MSAbased and VJMbased stiffness models were derived. To evaluate the deflections of the end
effector, the external loads were applied in different directions at multiple points in the robot
workspace. The computational cost and the difference in endeffector deflections were studied
and compared. MSA was found to be 2 times faster than VJM for this structure. The results
obtained showed that the MSA approach is more appropriate for the double pantograph
mechanism.

Ali Deeb A., Shahhoud F.
Abstract
This paper investigates the problem of object detection for realtime agents’ navigation using
embedded systems. In realworld problems, a compromise between accuracy and speed must be
found. In this paper, we consider a description of the architecture of different object detection
algorithms, such as RCNN and YOLO, to compare them on different variants of embedded
systems using different datasets. As a result, we provide a tradeoff study based on accuracy and
speed for different object detection algorithms to choose the appropriate one depending on the
specific application task.

Saypulaev G. R., Adamov B. I., Kobrin A. I.
Abstract
The subject of this paper is a spherical robot with an internal platform with four classictype
omniwheels. The motion of the spherical robot on a horizontal surface is considered and
its kinematics is described. The aim of the research is to study the dynamics of the spherical
robot with different levels of detailing of the contact friction model. Nonholonomic models of
the dynamics of the robot with different levels of detailing of the contact friction model are
constructed. The programmed control of the motion of the spherical robot using elementary
maneuvers is proposed. A simulation of motion is carried out and the efficiency of the proposed
control is confirmed. It is shown that, at low speeds of motion of the spherical robot, it is
allowed to use a model obtained under the assumption of no slipping between the sphere and the
floor. The influence of the contact friction model at highspeed motions of the spherical robot
on its dynamics under programmed control is demonstrated. This influence leads to the need
to develop more accurate models of the motion of a spherical robot and its contact interaction
with the supporting surface in order to increase the accuracy of motion control based on these
models.

Demian A. A., Klimchik A. S.
Abstract
This paper is devoted to the design of gravity compensators for prismatic joints. The
proposed compensator depends on the suspension of linear springs together with mechanical
transmission mechanisms to achieve the constant application of force along the sliding span of
the joint. The use of selflocking worm gears ensures the isolation of spring forces. A constantforce
mechanism is proposed to generate counterbalance force along the motion span of the
prismatic joint. The constantforce mechanism is coupled with a pinslot mechanism to transform
to adjust the spring tension to counterbalance the effect of rotation of the revolute joint. Two
springs were used to counterbalance the gravity torque of the revolute joint. One of the springs
has a moving pinpoint that is passively adjusted in proportion with the moving mass of the
prismatic joint. To derive the model of the compensator, a 2DoF system which consists of
a revolute and a prismatic joint is investigated. In contrast to previous work, the proposed
compensator considers the combined motion of rotation and translation. The obtained results
were tested in simulation based on the dynamic model of the derived system. The simulation
shows the effectiveness of the proposed compensator as it significantly reduces the effort required
by the actuators to support the manipulator against gravity. The derived compensator model
provides the necessary constraints on the design parameters.

Shamraev A. D., Kolyubin S. A.
Abstract
Animal running has been studied for a long time, but until now robots cannot repeat the
same movements with energy efficiency close to animals. There are many controllers for controlling
the movement of fourlegged robots. One of the most popular is the convex MPC. This
paper presents a bioinspirational approach to increasing the energy efficiency of the stateoftheart
convex MPC controller. This approach is to set a reference trajectory for the convex MPC
in the form of an SLIP model, which describes the movements of animals when running. Adding
an SLIP trajectory increases the energy efficiency of the Pronk gait by 15 percent over a range
of speed from 0.75 m/s to 1.75 m/s.

Almaghout K., Klimchik A. S.
Abstract
Although deformable linear objects (DLOs), such as cables, are widely used in the majority
of life fields and activities, the robotic manipulation of these objects is considerably more complex
compared to the rigidbody manipulation and still an open challenge. In this paper, we introduce
a new framework using two robotic arms cooperatively manipulating a DLO from an initial shape
to a desired one. Based on visual servoing and computer vision techniques, a perception approach
is proposed to detect and sample the DLO as a set of virtual feature points. Then a manipulation
planning approach is introduced to map between the motion of the manipulators end effectors and
the DLO points by a Jacobian matrix. To avoid excessive stretching of the DLO, the planning
approach generates a path for each DLO point forming profiles between the initial and desired
shapes. It is guaranteed that all these intershape profiles are reachable and maintain the cable
length constraint. The framework and the aforementioned approaches are validated in reallife
experiments.

Ali W., Kolyubin S. A.
Abstract
In this study, we discuss a new machine learning architecture, the multilayer preceptronrandom
forest regressors pipeline (MLPRF model), which stacks two ML regressors of different
kinds to estimate the generated gripping forces from recorded surface electromyographic activity
signals (EMG) during a gripping task. We evaluate our proposed approach on a publicly available
dataset, putEMGForce, which represents a sEMGForce data profile. The sEMG signals were
then filtered and preprocessed to get the featurestarget data frame that will be used to train
the proposed ML model. The proposed ML model is a pipeline of stacking 2 different natural
ML models; a random forest regressor model (RF regressor) and a multiple layer perceptron
artificial neural network (MLP regressor). The models were stacked together, and the outputs
were penalized by a Ridge regressor to get the best estimation of both models. The model was
evaluated by different metrics; mean squared error and coefficient of determination, or $r^2$ score,
to improve the model prediction performance. We tuned the most significant hyperparameters
of each of the MLPRF model components using a random search algorithm followed by a grid
search algorithm. Finally, we evaluated our MLPRF model performance on the data by training
a recurrent neural network consisting of 2 LSTM layers, 2 dropouts, and one dense layer on the
same data (as it is the common approach for problems with sequential datasets) and comparing
the prediction results with our proposed model. The results show that the MLPRF outperforms
the RNN model.

Kazakov Y., Kornaev A., Shutin D., Kornaeva E., Savin L.
Abstract
Despite the fact that the hydrodynamic lubrication is a selfcontrolled process, the rotor
dynamics and energy efficiency in fluid film bearing are often the subject to be improved. We
have designed control systems with adaptive PI and DQNagent based controllers to minimize
the rotor oscillations amplitude in a conical fluid film bearing. The design of the bearing allows
its axial displacement and thus adjustment of its average clearance. The tests were performed
using a simulation model in MATLAB software. The simulation model includes modules of a rigid
shaft, a conical bearing, and a control system. The bearing module is based on numerical solution
of the generalized Reynolds equation and its nonlinear approximation with fully connected neural
networks. The results obtained demonstrate that both the adaptive PI controller and the DQNbased
controller reduce the rotor vibrations even when imbalance in the system grows. However,
the DQNbased approach provides some additional advantages in the controller designing process
as well as in the system performance.

Savin S. I., Khusainov R. R.
Abstract
In this work, a nonminimal coordinate representation of tensegrity structures with explicit
constraints is introduced. A method is proposed for representation of results on tensegrity
structures in sparse models of generalized forces, providing advantages for code generation for
symbolic or autodifferentiation derivation tasks, and giving diagonal linear models with constant
inertia matrices, allowing one not only to simplify computations and matrix inversions, but also
to lower the number of elements that need to be stored when the linear model is evaluated along
a trajectory.

Mikishanina E. A.
Abstract
The problem of controlling the rolling of a spherical robot with a pendulum actuator pursuing
a moving target by the pursuit method, but with a minimal control, is considered. The mathematical
model assumes the presence of a number of holonomic and nonholonomic constraints, as
well as the presence of two servoconstraints containing a control function. The control function
is defined in accordance with the features of the simulated scenario. Servoconstraints set the
motion program. To implement the motion program, the pendulum actuator generates a control
torque which is obtained from the joint solution of the equations of motion and derivatives of
servoconstraints. The first and second components of the control torque vector are determined
in a unique way, and the third component is determined from the condition of minimizing the
square of the control torque. The system of equations of motion after reduction for a given
control function is reduced to a nonautonomous system of six equations. A rigorous proof of
the boundedness of the distance function between a spherical robot and a target moving at
a bounded velocity is given. The cases where objects move in a straight line and along a curved
trajectory are considered. Based on numerical integration, solutions are obtained, graphs of the
desired mechanical parameters are plotted, and the trajectory of the target and the trajectory
of the spherical robot are constructed.

Kurakin L. G., Ostrovskaya I. V.
Abstract
The stability problem of a moving circular cylinder of radius $R$ and a system of $n$ identical point vortices uniformly distributed on a circle of radius $R_0^{}$, with $n\geqslant 2$, is considered. The center of the vortex polygon coincides with the center of the cylinder. The circulation around the cylinder is zero. There are three parameters in the problem: the number of point vortices $n$, the added mass of the cylinder $a$ and the parameter $q=\frac{R^2}{R_0^2}$. The linearization matrix and the quadratic part of the Hamiltonian of the problem are studied. As a result, the parameter space of the problem is divided into the instability area and the area of linear stability where nonlinear analysis is required. In the case $n=2,\,3$ two domains of linear stability are found. In the case $n=4,\,5,\,6$ there is just one domain. In the case $n\geqslant 7$ the studied solution is unstable for any value of the problem parameters. The obtained results in the limiting case as $a\to\infty$ agree with the known results for the model of point vortices outside the circular domain. 
Astafyeva P. Y., Kiselev O. M.
Abstract
The article is devoted to a comprehensive study of linear equations of the second order
with an almost periodic coefficient. Using an asymptotic approach, the system of equations for
parametric subresonant growth of the amplitude of oscillations is obtained. Moreover, the time
of a turning point from the growth of the amplitude to the bounded oscillations in the slow
variable is found. Also, a comparison between the asymptotic approximation for the turning
time and the numerical one is shown.
