An Orthogonal Wheel Odometer for Positioning in a Relative Coordinate System on a Floating Ground

This paper introduces a planar positioning sensing system based on orthogonal wheels and encoders for some surfaces that may float (such as ship decks). The positioning sensing system can obtain the desired position and angle information on any such ground that floats. In view of the current method of using the IMU gyroscope for positioning, the odometer data on these floating grounds are not consistent with the real-time data in the world coordinate system. The system takes advantage of the characteristic of the orthogonal wheel, using four vertical omnidirectional wheels and encoders to position on the floating ground. We design a new structure and obtain the position and angle information of a mobile robot by solving the encoder installed on four sets of omnidirectional wheels. Each orthogonal wheel is provided with a sliding mechanism. This is a good solution to the problem of irregular motion of the system facing the floating grounds. In the experiment, it is found that under the condition that the parameters of the four omnidirectional wheels are obtained by the encoder, the influence of the angle change of the robot in the world coordinate system caused by the flotation of the ground can be ignored, and the position and pose of the robot on the fluctuating ground can be well obtained. Regardless of straight or curved motion, the error can reach the centimeter level. In the mobile floating platform experiment, the maximum error of irregular movement process is 2.43 (±0.075) cm and the RMSE is 1.51 cm.

Prototype of a remotely controlled model of a tugboat with an azimuth rudder and a hazard identification function

The author’s approach, based on the technology of control actions, is proposed for the interface display of the algorithm for the operation of an automatic tugboat with an azimuth rudder and a hazard assessment function. To define the object as presumably dangerous, the article used the formulas of the direct and inverse navigation problems. To compare the coordinates of the vessel and the perceived “hazard”, one first needs to enter data, process the information, and display information that is understandable for the decision-maker. To eliminate the misunderstanding of this situation, the operation of the danger prevention algorithm was demonstrated using the visual basic programming language as an example. When constructing an algorithm for the safe movement of the vessel and the existing danger, each object, even a stand-alone one, has many coordinate points. Knowing the number of points of coordinates of the vessel and “danger”, they were taken as n and m, respectively. The algorithm searches for the optimal point-object. The scheme of interaction of the components of the automatic tug azimuth model (ABA) is proposed. It is based on a Raspberry Pi single-board computer with an Arduino Mega board connected to it. A program has been written to control the ABA model using omnidirectional wheels to simulate maneuvering on water.

DEVELOPMENT OF DIRECTIONAL ALGORITHM FOR THREE-WHEEL OMNIDIRECTIONAL AUTONOMOUS MOBILE ROBOT

A The proposed system developed an omnidirectional algorithm to control autonomous mobile robots with three wheels. The implementation system consists of three Planet DC motors with rated power of 80 W for three wheels, three encoders for speed feedback, one encoder for distance feedback, and one digital compass sensor for angle feedback. The main system with an STM32F407 microcontroller is designed for directional control of wheels based the signal received from compass sensor and encoder and then controls three subsystems to adjust the steering speed of each wheel. The sub-system is built to control only one DC motor for each wheel with the built-in proportional integral derivative controller (PID) algorithm by an STM32F103 microcontroller. Furthermore, the directional control algorithm is developed for three omnidirectional wheels and a PID algorithm is designed to control the speed of DC motor for each wheel. From the results the proposed system has the advantages: (1) to auto adjust the angle and position; (2) to erase the sensor for tracking line of the automobile robot; (3) cost-effectiveness and high accuracy

Suboptimal Omnidirectional Wheel Design and Implementation

The optimal design of an omnidirectional wheel is usually focused on the minimization of the gap between the free rollers of the wheel in order to minimize contact discontinuities with the floor in order to minimize the generation of vibrations. However, in practice, a fast, tall, and heavy-weighted mobile robot using optimal omnidirectional wheels may also need a suspension system in order to reduce the presence of vibrations and oscillations in the upper part of the mobile robot. This paper empirically evaluates whether a heavy-weighted omnidirectional mobile robot can take advantage of its passive suspension system in order to also use non-optimal or suboptimal omnidirectional wheels with a non-optimized inner gap. The main comparative advantages of the proposed suboptimal omnidirectional wheel are its low manufacturing cost and the possibility of taking advantage of the gap to operate outdoors. The experimental part of this paper compares the vibrations generated by the motion system of a versatile mobile robot using optimal and suboptimal omnidirectional wheels. The final conclusion is that a suboptimal wheel with a large gap produces comparable on-board vibration patterns while maintaining the traction and increasing the grip on non-perfect planar surfaces.

Criteria of Motion Without Slipping for an Omnidirectional Mobile Robot

In this paper we present a study of the dynamics of a mobile robot with omnidirectional wheels taking into account the reaction forces acting from the plane. The dynamical equations are obtained in the form of Newton – Euler equations. In the course of the study, we formulate structural restrictions on the position and orientation of the omnidirectional wheels and their rollers taking into account the possibility of implementing the omnidirectional motion. We obtain the dependence of reaction forces acting on the wheel from the supporting surface on the parameters defining the trajectory of motion: linear and angular velocities and accelerations, and the curvature of the trajectory of motion. A striking feature of the system considered is that the results obtained can be formulated in terms of elementary geometry.

Modular Transport and Sorting System with Omnidirectional Wheels

The paper refers to the development of an intelligent sorting and transport system. This research aims to develop such systems and solve problems in multi-directional transport as well as the development of a sorting, transport and positioning system that can be used in various fields. At the same time, the omnidirectional transport system is a modular transport and sorting system. It consists of several small hexagonal transport cells, each with three individually operated omnidirectional wheels. By individually controlling the wheels, objects can be transported freely in all directions. This opens unlimited possibilities to create new concepts for handling materials or to improve existing classic ones. Due to the modular construction and the individual control of the omnidirectional wheels, the sorting tasks can be adapted very quickly. This will allow you to perform different tasks in very small areas. Individual control of objects also allows for exact alignment or individual rejection of objects. The system has been designed to transport work objects. To design the module, it was necessary to create its scale geometric model using the Autodesk Inventor Professional 2018 design environment. To make the module, it was used through the rapid prototyping process with Fused Deposition Modelling, the material used being Polylactic Acid. The solution adopted allows any transported object to always be supported on at least three wheels, this allows the direction of movement of the object to be controlled by the movement of the wheels.

Design and Control of 7-DOF Omni-directional Hexapod Robot

Legged robots have great potential to travel across various types of terrain. Their many degrees of freedom enable them to navigate through difficult terrains, narrow spaces or various obstacles and they can move even after losing a leg. However, legged robots mostly move quite slowly. This paper deals with the design and construction of an omni-directional seven degrees of freedom hexapod (i.e., six-legged) robot, which is equipped with omnidirectional wheels (two degrees of freedom are used, one for turning the wheel and one for the wheel itself) usable on flat terrain to increase travel speed and an additional coxa joint that makes the robot more robust when climbing inclined terrains. This unique combination of omnidirectional wheels and additional coxa joint makes the robot not only much faster but also more robust in rough terrains and allows the robot to ride inclined terrains up to 40 degrees and remain statically stable in slopes up to 50 degrees. The robot is controlled by a terrain adaptive movement controller which adjusts the movement speed and the gait of the robot according to terrain conditions.