Extras Materiale Scara Metalica. Home · Documents Sfântul Ioan Scărarul – Scara Raiului sau Scara Dumnezeiescului Urcuş · Descopera. 9 – Scara Sfantului Ioan Scararul si Invataturile lui Avva Dorotei. Uploaded amnessia. Sfântul Ioan Scărarul – Scara Raiului sau Scara Dumnezeiescului Urcuş. 9 – Scara Sfantului Ioan Scararul si Invataturile lui Avva Dorotei. Uploaded Sfântul Ioan Scărarul – Scara Raiului sau Scara Dumnezeiescului Urcuş. Uploaded.
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Post on Jan 36 views. Kinematic of Robots M.
Raiiului term robot was first introduced into our vocabulary by the Czech playwright Karel Capek in his play Rossums Universal Robots, the word robota being the Czech word for work. This term could disappear but instead, still being used thanks to writers which used to define living mechanics similar to humans. The real robot machine has a different development of its term robot. Real industrial robots main backgrounds are ligated to the tele-manipulators, which are machines that allow to control several dangerous materials.
The robotics without colloquial robot concept it is the industrial robot, used in industrial production during 30 years for substituting humans beings in repetitive or dangerous tasks, according to production requirements.
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There are several issues to establish a definition of robot, since several markets and countries has its own definition. The most accepted definition is the given by RIA “A robot is a reprogrammable, multifunctional manipulator designed to move material, parts, tools or specialized devices through variable programmed motions for the performance of a variety of tasks.
Revolute manipulator Parallel manipulator Spherical configuration SCARA configuration Cylindrical configuration Cartesian configuration Figure 2 Grades of freedom GOF Figure 3Robots morphologies scxra Building a robot is a real engineering challenge because it involves a well knowledge of areas such as mechanics, electronics, programming and control.
To have success in this activity, we need to consider all the aspects and make a strategically activities plan to be performed. A SCARA robot is distinguished by being quick in its movements, so it is used in the arrangement of objects, sealed, transportation, etc. In addition we need to achieve an adequate control with the use of DC motors, forgetting stepper motors or servomotors normally they facilitate this task.
We are going to follow the methodology of Bolton, because it is easier than Shigleys methodology and scafarul pretend to advance in the SCARA robot step by step in the best way. This methodology consists in the next diagram showed in Figure 2: Figure 4 Methodology diagram Recognition of the needProblem analysisSpecificationPossible solutionsSelection of a suitable solutionProduction of a detailed designProduction of working drawings 6 Recognition of the need.
At school we have a sscararul of projects where our knowledge is prove, so we need to find a way to build a specific type of robot. So to approve some of the subjects we need the construction of a specific robot that do a task. Analysis of the problem.
Actually we have some projects scsrarul we need to end for the final of the quarter so for a project we combine different subjects to create only one project. The Joint 1 and the Joint 2 is the shoulder, then the Joint 3 works as the elbow, finally the Joint 4 is the wrist.
Knowing how a SCARA robot work, we thought in a robot that works with a conveyor in a line production, where our robot can classify a product marking a piece with a specific message or code.
Thanks the velocity of the robot, and the similarity of the robot with an arm, we can see that this task is not impossible, and that we can make it.
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This robot can go to a specific position with a message sent on an App. Also our robot will have 3DOF. Structure a work plan to construct a SCARA robot while this quarter and define the activities for each member of the team, the materials that we need and the goals to achieve. Manipulation through an app. Matlab and Labview interface Theory Position The position in robots is used for determine at which point your robot will move after an instruction, all the positions can be represented in a 3D coordinated system.
Orientation The orientation in a three dimensional space is given by three degrees of freedom, and those ones are linearly independents. The orientation is used because its necessary know not just the position, also is important to know the orientation of the robot, its necessary to create a rotation matrix to know or determine how much the robot will be positioned in relation with the original position.
Rotation Matrixes Rotation matrixes are used for indicate how much the robot will rotate and in which axis will rotate, to make rotations with objects its common to assign a new system and then study the relations between old a new system.
See Figure 9 and Figure Figure 7 Position in 2D and 3D Figure 8 Orientation Figure 9 Rotation equations 8 Figure 10 Rotation matrixes Homogeneous Matrixes The homogeneous matrixes are used to represent the position, orientation, scale and camera locations of objects in real and virtual spaces.
See Figure 11 and Figure 12 Figure 11 Homogeneous matrixes Figure 12 Homogeneous matrixes 9 Translation Matrixes To move the coordinate system to a desired point its required homogeneous matrix with the identity rotation matrix and distances of movement.
Figure 13 Transalation matrixes Order with transformations It is possible to perform several transformation in one matrix because all information will be contained in a homogeneous matrix If fixed system is OXYZ and transformed is OUVW are coincident, then transformation matrix will be the same as the Figure 14 Figure 14 Transformation matrix If OUVW system is obtained by rotations and translations defined with fixed system OXYZ, then transformation multiplications must be performed with previous multiplying, and translations always must be in the beginning.
This robotic manipulator is part of a structure that is a Kinematic Open Chain, in where one of the side of the structure are fix to a base, and the other side can work with any object in the space.
For the direct kinematic of the robots, the Denavit-Hartenberg theory propose a transformation homogenous matrix that represent the movement of a link NOTE: Depending on the number of the links we will represent a transformation homogenous matrix. So this matrix is represented by the next matrix: Figure 15 Homogeneous matrix So to analyze how the coordinates, the movements and the turn of the robots are placed we need to know that: We need to considerate the length or the distance that are between the links.
When a joint of the robot turn we need to analyze when the analysis of the robot is easier, to make our analysis easy. To assign where the coordinate systems are going to be, we need to start from the base to the end effector. The base coordinate X needs to point to the end effector. When our coordinate system is parallel to the end effector the Z coordinate need to point it. When we have our work draw, and all the specifications are placed we need to fill a table, where we can know the displacement and rotations we have in each link.
With this table we need create a matrix depending the number of links, in base of our translation homogenous matrix, and we substitute the values. Finally to complete de Denavit-Hartenberg theory we need to multiply all the matrix for example: We repeat this step from Y, only instead the first row from matrix 0A2we use the second.
Finally we repeat the step from Z, but instead we use the third row from the matrix 0A2. Theory of Control In specific words, the control is the indirect manipulation of magnitudes on a system through another system that is called control system.
There are two types of control, where we can apply in the Scara Robot they are: Analog Control and Digital Control. Analog Control Type of control that is able to determine the degree of touch or movement we make about it. Figure 17 Conttrol System 12 We can found an open loop or a closed loop. An open loop is when the process is between an input and an output while a closed loop has a feedback measurement that will make the system stable.
Figure 18 Open Loop vs. Closed loop The Laplace transform is the key of this controller.
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Digital control Its an implementation of control using a programmable logic with the supply of tools as Analog-Digital converters, digital controllers and Digital. Analog converters, sampling an analog signal in a period of time obtaining a sequence. The Z transform is the main feature of this control. Figure 19 Digital control system 13 Mechanic design The mechanical design is to provide one or more solutions to define a product so that meets the requirements and restrictions established.
The stages of the design are: Synthesis grouping of elements 3.
Analysis finite scararrul 4. Representation plans Technical characteristics Motors: It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started. HC could be setting to Master or Slave by user. HC has be designed Master or Slave when the factory, user couldn’t change the role. I have not been able to verify this yet. I have been told that some modules have this pin not connected at all?
VCC is indicated in the range of 3. The module worked for me both with 3. Note that this signal is using 3. At least on my module the pin was always low, regardless if paired or not. Figure 26General characteristics 17 Material: Aluminium and acrylic Weight: So the software design consist in 4 pieces: A base Link 1 Link 2 Plunger First as a fixed part we select the base that will be the starting point of the assembly.
The base has to be a strong part, because it support all the weight of the links, also it will protect scafarul connections and the material of the electronic scaragul the control system. A specific request of the design is a part where the motor can sheathe whit the link 1. Then, the Link 1 has sheathe with the base, so it have to be above of the base, and need to have a possibility of rotation The grades of freedom depends in the kind of task of the robot. This description also apply on the Link 2, but this one have to sheathe in the Link 1.
Finally the plunge have to be at the end of the link to, and has the liberty to translate only in the z axis. The disadvantages of this design are: They cant charge a lot weight. Their movement in the z axis is depends in the height of the robot They only work on specific tasks.
So first, we create a simple design that covers that requirements. When we chose the material we taught in something cheap and useful: So, the base is resistant, with a hard material, it has 5 machined acrylic pieces. The links are made of aluminum with acrylic tops, linked by a tube fixed to a sheet containing a bearing. The final link contains xcara end effector that have movement thanks to a rack-pinion.
The acrylic pieces were done on the CNC Mill machine. Other pieces were made in the Mill and the turning, as the joints, the sheets, the links, the end effector and the base. Control system 30 Control System Design.
Control a DC motor means that some tests are needed to parameterize its operation, because the model of a motor includes variables of resistance, viscosity, inertia, inductance and some others. Figure 34 Representation of the scararil as a close system These variables were obtained through a test, where we require a regulated source, an oscilloscope with ends for voltage and current a tachometer r.
The probes made to obtain each parameter was: Figure 33 Control in a DC motor 31 1 Remove the gear box of the motor reducer because its most convenient for the veracity of the probes.