Search

Robotics is an interdisciplinary field and there exist several well-known approaches to represent the dynamics model of a robot arm. The robot arm is an open kinematic chain of links connected through rotational and translational joints. In the general case, it is very difficult to obtain explicit expressions for the forces and the torques in the equations where the driving torques of the actuators produce desired motion of the gripper. The robot arm control depends significantly on the accuracy of the dynamic model. In the existing literature, the complexity of the dynamic model is reduced by linearization techniques or techniques like machine learning for the identification of unmodelled dynamics. This paper proposes a novel approach for deriving the equations of motion and the actuator torques of a robot arm with an arbitrary number of joints. The proposed approach for obtaining the dynamic model in closed form employs graph theory and the orthogonality principle, a powerful concept that serves as a generalization for the law of conservation of energy. The application of this approach is demonstrated using a 3D-printed planar robot arm with three degrees of freedom. Computer experiments for this robot are executed to validate the dynamic characteristics of the mathematical model of motion obtained by the application of the proposed approach. The results from the experiments are visualized and discussed in detail.

This research considers the design of a sensor system for walking robot which can be used for coverage path planning and precise surface exploration. The paper presents an updated mechanical design of a minimalistic walking robot with a fixed step size. The robot has only two degrees of freedom. The specific mechanical design prevents the accumulation of any odometry error and does not require any external navigation system. The robot is equipped with a variety of distance and tactile sensors which allow precise exploration of the surface and any high or low spots of the surface to be located. This paper proposes an approach for path planning and surface exploration by using the proposed sensor system. Despite that the robot is based on a minimalistic approach, it can move and operate on complex surfaces. Also, by altering its movement direction it can effectively use its sensor system for distant global object scanning or for local exploration of the walking surface. The conducted experiment showed that the presented in this research mechanical design of a walking robot with fixed step can be used for precise surface exploration.

The development of 3D printed humanoid hand is presented in this paper. An original idea of printing the fingers completely assembled is introduced. Main kinematic characteristics of finger of humanoid hand are researched using concepts of open kinematic chain. An algorithm for determining the main kinematic characteristics of the finger, such as workspace and manipulability, is implemented. The results for all fingers, without the thumb, are described and compared using their average size and joint constraints. The benefits and applicability of the proposed research are discussed, as well as the application of 3D printing technology.

This paper considers the hard constraints in the movement of the joints of robotic manipulators executing repetitive tasks in the presence of measurement noise in the dynamic model. In our research work we have established that subject to these conditions the Iterative Learning Control (ILC) is one of the best methods performing such tasks with high precision. The existing applications of ILC don’t take in consideration the inherent nonlinearity of the dynamic model of a robotic manipulator neither the hard constraints in state space. This paper presents a robust and convergent Constrained Output ILC (COILC) method for non-linear hard constrained systems like industrial robots. Unlike known ILC methods the COILC employs a novel algorithm to cancel the currently executing iteration before the occurrence of a violation in any of the state space hard constraints. This way COILC resolves both the hard constraints in the state space and the transient growth problem, which is a major obstacle in applying ILC to non-linear systems. The convergence and the performance of the proposed numerical procedure are experimentally evaluated through computer simulation of the well-known SCARA-type robot TT-3000. The obtained results are discussed and demonstrate that COILC is suitable for solving hard constrained state space problems of non-linear systems in robotics with certain inaccuracies in the dynamic model.

The purpose of our study is to research the usability of a tele-controlled service robot by performing real tests of the robot with the elderly. Robot control is based on a multichannel system for data distribution from external devices, such as – joystick, virtual joystick, microphone, Kinect, and Leap Motion to provide effective assistance of the elderly for their different needs. In the paper, there are described the functionalities of the robot ROBCO 17 and the principles of the performing of the experiments. Finally, we present the results of the impressions of the elderly and their recommendations for future upgrades of the service robot.