Václav Krys

Screw connection and its load capacity in components made by rapid prototyping technology

The Department of Robotics at The Faculty of Mechanical Engineering has recently recognized the benefit of using components produced by rapid prototyping technology (RP) [1] over peripherals, in producing and servicing robotic devices. The percentage of the parts produced by rapid prototyping technology in some devices may exceed 80 percent. Employing this technology means, that connecting the various parts of the mechanical structure is done by bolting the joints. In doing so, the question of maximum fastening torque of such joints arose, giving consideration to the unknown mechanical material properties of the parts in the place of force action. This paper will deal with maximal torque and hence the force acting at the screw connection of the part made by RP technology. It also addresses the question of how the size of the area under the bolt head affects the load capacity of screw connection. Great emphasis is assigned to testing the bolt joint load capacity, relevant to the testing of the material samples. Additionally, the article provides specific measurement values, which may serve as a guideline for the design of joints using this concept. The article also builds on the knowledge gained from previous testing of the screw connections made by 3D print technology [2].

System for automatic collisions prevention for a manipulator arm of a mobile robot

Control systems of mobile robots controlled remotely by a human operator using only limited visual feedback from camera subsystem can aid the operator in various ways. This paper deals with automatic collision detection for manipulator arm mounted on a mobile robot - the goal of the system is to prevent any possible collisions between the arm and the robot or the arm itself. Implementation of the system uses the separating axis algorithm on pairs of oriented bounding boxes enveloping mechanical components of the robot. Practical testing of the whole control system was done on two existing mobile robots.

Implementation of polycarbonate material mechanical properties of rapid prototyping into system CREO, laboratory verification of the results

The article deals with specification and subsequent implementation of mechanical properties of a polycarbonate material used for functional prototypes produced by Rapid Prototyping based on input data from 3D models designed in CAD system CREO 2.0. The implementation of specific properties of material PC-10 for the printer FORTUS 360mc L in the CAD system will allow a more efficient use of Rapid Prototyping for production of functional prototype parts, because it will be possible to determine their strength characteristics at the design stage by the simulation model analysis.

The Synthesis and Testing of a Shaped Wheel for Stairs Climbing Robot

This article describes the process of designing and testing of shaped wheels for a mobile robotic stairclimbing system. It explains the basic principle of the shaped wheel and a synthesis of the shape and dimensions of the wheel segment for specified dimensions of the stairs. Before building a reduced prototype of a chassis with the designed wheels, simulations of its virtual model were performed in the ADAMS simulation environment. Functionality of the suggested solution was verified by building a prototype and its testing. The article is concluded with description of the achieved results and other research activities planned in the sphere of locomotive subsystems for stairclimbing.

Shaped Glued Connection of Two Parts Made by Rapid Prototyping Technology

An increasing number of designs and subsequent production of parts created by the Rapid prototyping (RP) [1] technology led to a problem with the maximum workspace of the 3D printer. Due to this reason, it was necessary to work on the solution of joining the parts to overcome the limited workspace of the printer. This article is devoted to glue joints analysis of two parts made by RP technology. A great emphasis is given to the load capacity testing of the parts made this way. The measured values than may serve as a lead for the construction design of the outlined joints. The article builds on the knowledge gained during the previous testing of the screw connections of parts made by 3D printing technology [2].

Bend Testing on Components Manufactured by Rapid Prototyping Technology in Combination with other Materials

The knowledge of the mechanical properties of the material used is a necessary prerequisite for the quality design of any structural unit. It applies to components manufactured using Rapid Prototyping technology (hereinafter only RP) multiple times, because it is not enough to only know the mechanical properties of a material from which the components are printed. Other factors affect the component printing, such as the orientation of the printed component, the selection of the components internal structure, possibility of connection with other materials, etc. The article follows from the previous research of the experimental determination of the bend strength of parts printed by RP technology from polycarbonate, which focuses on bend-testing of samples printed with various internal structures. This article expands on the original research by experimental determination of the bend strength of printed components, which form a unit with another material. The obtained information can be utilised in the design of components manufactured with RP technology using professional printers.

Bend Testing of Parts Made by Rapid Prototyping with Respect to Possible Use in Robotics

Recently, the Rapid Prototyping technology (RP hereafter) has been increasingly used for a final product, which requires detailed knowledge of designing parts made by the RP technology. In order to apply parts made by the RP technology in robotics, and design in general, in a wider range, one of the most important material parameters is their bend strength. The paper describes an experimental determination of bend strength in parts printed on a 3D printer. The parts were made of polycarbonate. The tests were carried out in parts with various types of internal structure. The achieved results can be implemented when designing parts made by 3D printing provided that professional printers are used.

Simulation System for Teleoperated Mobile Robots

The paper presents a mobile robot simulator designed primarily for teleoperated mobile robots, to aid in the prototyping phase of development or as a training tool for existing robots. The simulator uses virtual reality with realistic 3D graphics to simulate complex behaviour of a mobile robot in various conditions and with different properties. The system can be used to discover or verify driving and manipulation abilities of a mobile robot defined by its kinematics structure and dimensions, and also to simulate navigation using the camera subsystem containing one or more cameras.

Kinect v2 infrared images correction

This article presents a novel correction filter for infrared images captured by Kinect v2 sensor. Intended application areas are described and the basic concept of proposed sensory subsystem as well. Preliminary tests of the sensor Kinect v2 in real conditions gave promising results, therefore in-depth analysis of its applicability was performed. In the framework of the analysis, a relation between infrared value and a distance of captured surface was evaluated for different colors of the surface. Based on that relation and on additional information about the depth of a pixel, a correction filter was created. The filter allows improving infrared image in order to increase the success rate probability to be able to detect specific features and key points by algorithms more easily. Outputs from the filter on real conditions data sets are also presented in the article.

The synthesis of a segmented stair-climbing wheel

The article describes the process of development of an essentially new wheel suitable both for moving on flat ground and for travelling on stairs. The stair-climbing wheel is composed of rotary circular segments arranged around a shared carrier with arms to form a complete circular profile of the wheel adapted for moving on flat ground; for travelling on stairs, individual segments are rotated by an appropriate angle to touch down tangentially on the stepping surface of the stairs. The dimensions of individual segments, the centre of rotation of individual segments and the angle of their partial turn have been chosen so that the length of the arc along which the circular segment rolls is equal to the length of the stepping surface of an average stair, and, at the same time, the circular segment touches down tangentially on the stepping surface while the wheel turns around the edge of the previous segment. Using the rotation angle of the turnable segments, the wheel can be adapted to the height of non-standard stairs. The segments can be inclined in both directions for bidirectional movement of the wheel up and down the stairs. An undercarriage equipped with these wheels can be used in the field of exploratory robots and for the transportation of persons and materials on stairs.