Industrial robots have become one of the effective support tools for human labor. Robots are a solution to replace humans in repetitive tasks and in environments where humans cannot work. Robots have become one of the factors responding to the Industrial Revolution 4.0. Automatic control devices require high-precision control quality. Therefore, in this paper, we focus on researching controlling the position of the actuator accurately based on the PID algorithm. First, we study the forward and inverse kinematics of a three-joint robot. Second, we design the robot model on inventor software and transfer the 3d model in inventor software to Matlab Simmechanics. Third, modeling robot model on Simulink to simulate and evaluate the results achieved

In engineering and science problems, the data being considered are often known in the form of sets of discrete points, not as a continuous function. In applications, the values of the discrete data at specific points may be required to estimate. To solve these problems, a common mathematical approach is to use the interpolation method. In this paper, we use the cubic natural spline interpolation method to build approximate functions for some real data in Vietnam such as data on rice output and rice area of cultivation, data on expenditure and income per capita. The data used in this paper are extracted from the General Statistics Office of Vietnam. We develop some Matlab programs to find the coefficients of splines and calculate the values of the interpolation functions at specific points. Using the obtained interpolation function, some missing values in the data on income and expenditure per capita in the Southeast region of Vietnam in 2019 and 2021 are estimated. Furthermore, some unknown data on rice productivity and cultivation area are obtained in a similar manner. A good agreement between the calculated values and actual values are found.

In this topic, we applied the Fmincon function to the optimum question when choosing the structure of a 7-bar bearing steel bearing, divided into groups of the same size, including group 1 (1, 2 bars), group 2 (3, 4, and 5 bars), and group 3 (6, and 7 bars) with three fixed head points and two bearing points. Using the Matlab software code, we have identified the structures of each group of steel bars corresponding to the radius of 1.564 cm, 3.509 cm, and 4.724 cm, respectively. Through this, we can identify the 1, 2, and 3 bars that are resistant to traction; the 3, 5, 6, and 7 bars that are subject to compression; and the 4 bars alone that are not subject to the action of the force. The results show that using the optimal method, we choose the different sizes, thicknesses, and volumes of the pipe so that it best suits the technical requirements of the paper, to avoid waste of raw materials, affecting the economic cost.