Robot Design Basics

of 21
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
    A robotic arm  is a type of  mechanical arm, usually programmable, with similar functions to a   human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints allowing either rotational motion (such as in an articulated robot) or translational (linear) displacement. [1][2]  The links of the   manipulator can be considered to form a kinematic chain. The terminus of the kinematic chain of the manipulator is called the end effector  and it is analogous to the human hand.  manipulator is called the end effector  and it is analogous to the human hand.  Types      Cartesian robot  / Gantry robot : Used for  pick and place work, application of sealant, assembly operations, handling machine tools and arc welding. It's a robot whose arm has three prismatic  joints, whose axes are coincident with a Cartesian coordinator.    Cylindrical robot : Used for assembly operations, handling at machine tools, spot welding, and handling at diecasting machines. It's a robot whose axes form a cylindrical coordinate system.    Spherical robot / Polar robot  Used for handling machine tools, spot welding, diecasting, fettling machines, gas welding and arc welding. It's a robot whose axes form a polar coordinate system.    SCARA robot : Used for pick and place work, application of sealant, assembly operations and handling machine tools. This robot features two parallel rotary joints to provide compliance in a plane.    Articulated robot : Used for assembly operations, diecasting, fettling machines, gas welding, arc welding and spray painting. It's a robot whose arm has at least three rotary joints.    Parallel robot : One use is a mobile platform handling cockpit flight simulators. It's a robot whose arms have concurrent prismatic or rotary joints.    Anthropomorphic robot : It is shaped in a way that resembles a human hand, i.e. with independent fingers and thumbs. Applications of some notable robotic arms   In space, the Space Shuttle Remote Manipulator System also known   as Canadarm or  SRMS and its successor  Canadarm2 are examples of multi degree of   freedom robotic arms. These robotic arms have been used to perform a variety of tasks such as inspection of the Space Shuttle using a specially deployed boom with cameras and sensors attached at the end effector, and also satellite deployment and retrieval manoeuvres from the cargo bay of the Space Shuttle. [5]       The  Curiosity   rover  on the planet Mars also uses a robotic arm. [6][7][8][9]       TAGSAM is a robotic arm for collecting a sample from a small asteroid in space on the spacecraft OSIRIS-REx. [10]       The 2018 Mars lander  InSight has a robotic arm called the IDA, it has camera, grappler, is used   to move special instruments. [11]     A serial robot arm can be described as a chain of links that are moved by joints which are actuated by motors. An end-effector , also called a robot hand, can be attached to the end of the chain. As other robotic mechanisms, robot arms are typically classified in terms of the number of  degrees of   freedom. Usually, the number of degrees of freedom is equal to the number of joints that move the links of the robot arm. At least six degrees of freedom are required to enable the robot hand to reach an arbitrary pose (position and orientation) in three dimensional space. Additional degrees of freedom allow to change the configuration of some link on the arm (e.g., elbow up/down), while keeping the robot hand in the same pose. Inverse kinematics is the mathematical process to calculate the configuration of an arm, typically in terms of joint angles, given a desired pose of the robot hand in three dimensional space. Robotic Hands [edit]     The end effector, or robotic hand, can be designed to perform any desired task such as welding, gripping, spinning etc., depending on the application. For example, robot arms in automotive assembly linesperform a variety of tasks such as welding and parts rotation and   placement during assembly. In some circumstances, close emulation of the human hand is desired, as in robots designed to conduct bomb disarmament and disposal. [14]     Further information: Robot end effector   Degrees of Freedom (DOF)  The degrees of freedom , or DOF, is a very important term to understand. Each degree of freedom is a joint on the arm, a place where it can bend or rotate or translate. You can typically identify the number of degrees of freedom by the number of actuators on the robot arm. Now this is very important - when building a robot arm you want as few degrees of freedom allowed for your application!!! Why? Because each degree requires a  motor , often an  encoder , and exponentially   complicated algorithms and cost. Denavit-Hartenberg (DH) Convention The Robot Arm Free Body Diagram (FBD)  The Denavit-Hartenberg (DH) Convention is the accepted method of drawing robot arms in FBD's. There are only two motions a joint could make: translate and rotate. There are only three axes this could happen on: x, y, and z (out of plane). Below I will  show a few robot arms, and then draw a FBD next to it, to demonstrate the DOF relationships and symbols. Note that I did not count the DOF on the gripper (otherwise known as the end effector ). The gripper is often complex with multiple DOF, so for simplicity it is treated as separate in basic robot arm design. Notice between each DOF there is a linkage of some particular length. Sometimes a  joint can have multiple DOF in the same location. An example would be the human shoulder. The shoulder actually has three coincident DOF. If you were to mathematically represent this, you would just say link length = 0.   
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...

Sign Now!

We are very appreciated for your Prompt Action!