QUESTION
SOLUTION
Table of Contents
Introduction…………………………………………………………………………………………………………………………………….3
The basic hardware set-up………………………………………………………………………………………………………………3
The robots in analysis………………………………………………………………………………………………………………………5
Robots in motions…………………………………………………………………………………………………………………………….5
The work volume………………………………………………………………………………………………………………………………7
The Robot Drive System…………………………………………………………………………………………………………………….7
The Grippers………………………………………………………………………………………………………………………………………9
The Sensors………………………………………………………………………………………………………………………………………..9
The Robot Specifications………………………………………………………………………………………………………………………10
Refrences………………………………………………………………………………………………………………………………………………11
Introduction
This document does a detailed study of the technology and its architecture, to control a mobile robot system from a remote system. There can be a number of different alternatives about how to control such a system, after all a technology which suites the user, gives best performance, is cost effective, and which would find technical support for a foreseeable future, is the technology of choice.
The alternatives can be of a wide variety, hardware & software, and the one which mingle with each other so as to produce a good combination. (Walzade,2009)The radio frequency technologies which are the backbone of the mobile devices, including this one has seen a lot of advancements with time. This is the basic thing which makes us imagine the system of robots, moving in the direction of our choice supported by a small Li-Ion rechargeable battery, to collect invaluable pieces of information and data. The body of the mobile robots is built with an objective to make them capable of rolling into areas from where the data is supposed to come. It should have the parts which can rotate freely into different direction, like the arm in which the camera /webcam is fitted.
We here in this document are going to discuss such technologies which enable the robots in functioning to the best of the requirements of the human needs. We would first start with the hardware technologies, protocols, and standards which make up cost-efficient usable robots, and then we shall be turning towards the client-server and remote technologies which have pigmyied the distances, without compromising the accuracy of the results.
The basic hardware setup
The hardware components which serve the purpose of general mobile robots would be discussed first. What are the basic parts which make up a robot?
Above figure gives the view of the hardware parts of the SRV robot.
Let us list those parts, without which we cannot think of these robots:
- A processor capable of controlling all the parts of the robots.
- A camera with required pixels.
- The robot chassis
- Motors and treads for movement.
- Infrared sensors
- Wireless transmitter receiver system to make communication possible
The robots for research require a good capacity processor which is basically a microcontroller chip which is programmed in c or basic control the parts of the robot to run in unison. The user doesn’t need to bother about how the microcontroller is programmed. This is all the headache of those who design the robots. After all the users are supposed to interact with the robots, through the GUI (graphical user interface) built to control the system of robots.
The microcontrollers is like a small computer which has a processing ability and flash memory, which can interact with the peripheral devices, produce required signal for the proper functioning.(Craig,2008) It is programmed in a high level assembly programming languages. The programmers, who program the robots, generally write those programs in c language. These c programs are in turn converted into the assembly language by the compilers which are specially built to serve the purpose of these microcontrollers. The microcontrollers come in a particular series and they vary in performance with the designer vendors.
The peripheral devices attached to the microcontroller, send interrupt signals in order to gain access to the resources of the later. These interrupt signals have been graded according to their level of importance, in which they should be served the processor. When the processor gets an interrupt signal, it looks for the level of the interrupt, then if required would suspend the read/write cycles allocated to other processes, and would process the interrupt signal. Suppose a case when a peripheral device need to write to the memory of the microcontroller, it would send an interrupt signal to allow it to access the memory. The microcontroller would check whether the interrupt is important enough to suspend the ongoing process. If it finds that the request of the peripheral device must be fulfilled then, it would latch-up the current process and give the peripheral device an access to the memory. This particular process is known as DMA.
The memory of the microcontrollers comes as EEPROM flash devices, which can be flashed with the help of electric signal. This increases the reusability of the memory. It is important that while assembling a robot it should be taken into care that the maximum capacity to which the microcontroller browses the memory depends on the bit-capacity of the microcontroller. Suppose the microcontroller has a four bit capacity, then it can support memory up to only bits. Thus it is required to check the bit capacity of the microcontroller, as it may lead to either excess or shortage of memory space. These days maximum microcontrollers come in 32-bit capacity, which is enough for most of the research purposes and enough amount of memory can be allocated to the robots for all purposes
The robots require a camera which in general a low pixel capacity, so that we are able to store the images and videos of the scenes captured in small space and with less processing required by the microcontroller.(Craig,2008) The body frame of the robots should be made taken into consideration the environment of the research field. The motors moving the arms and the wheels are also important feature needed to consider before the robots are made, as it can affect the mobility of the robot.
The sensors are the eyes of the robots. The sensors are the devices which convert a physical quantity so as it is readable to the user. There may be many sensors attached to the system of the robot, each with a different purpose. Some of the sensors may help robots to get the temperature, humidity, presence of suspended particles in the environment. The nature of sensors should be decided with the purpose or the goal of the experiment in the consideration.
There can be errors in the measurements of the sensors, which should be also considered in a limit to the results expected.
The wireless devices which are attached to the robots are very important as they carry the signal to and from the robots. The common wireless devices which make this possible are the WLAN technologies, which help the user to setup a contact with the robot from their working system. These systems are compatible with most of the computing systems. They are based on the IEEE 802.11 standards, that too mostly b & g standards.
Till now we talked basically of the hardware enabling technologies of the robots. However the robots we are talking here require less interaction from computers.
The Robots in analysis
The robots which we would talk here are used in a press shop where the production of automobile parts is done in bulk. These automobile parts are small and precise work needs to be done. Therefore, it is required to load and unload the raw materials is required frequently. This work would result in boredom to a human operator and hence less production. Thus for this purpose automation is required.
A robot arm needs to be designed for loading and unloading the raw materials. The robot arm should be developed as a stand-alone machine which can be integrated to the existing environment. The sizes of the components handled by the robots vary in size so the robots should be programmable. The operators of the robots would not be highly skilled people, hence it’s required that the design of the robots is very simple to use.
This is required that the robots should be taking minimum information from the operators. The robots should be deciding themselves the path and control for picking and placing the jobs. These robots do not have any interface to work with from the computer, because it would be very uneconomical for the press shops to have a single computer assigned to a particular robot. The robots should be able to perform their job with the help of microcontroller-based system.
The Robots Motions
The robots in the concern should be programmable robot which performs a task continuously until asked to do another job, that it is programmed to perform another task. These robots perform their tasks by mostly by moving the body parts, the arms and the wrist. The joints in the first two and the last one of the robotic motions fall in different categories or degrees of freedom, mostly between 4 to 6 degrees of freedom.
Figure 1 the four basic anatomies of robots (a) Polar (b) Cylindrical (c) Cartesian (d) Jointed arm
The motions of the robots are accomplished with the help of powerful joints .These joints are connected by strong arms called links. The work is mainly completed by the relative motion of the links rotational or linear. The linear motion of the links is achieved by the sliding or translational motion of the connecting links. There are basically three degrees of motion associated with the arm and the body parts:
1. The radial transverse: This refers to the back and forth motion of the robotic arm from the vertical center of the robot.
2. The vertical transverse: This refers to the up and down motion of the robotic arm.
3. The Rotational transverse: This refers the rotation of the arm of the robot.
There is also motion of the wrist associated with the robots. The three types of motions related to wrist motion are:
1. Wrist-roll: This is the rotational motion of the wrist about its own axis.
2. Wrist Pitch: It is the motion of the wrist arm when the wrist roll is in central position. The wrist pitch gives the up and down motion of the wrist.
3. Wrist yaw: It is the motion of the wrist when the wrist roll is in central position. This is the right or the left motion of the wrist as compared to up and down of the wrist pitch.
The work Volume
The work Volume of a robot describes the amount of space the robot arm is able to cover. This depends
Figure 2 degrees of freedom for the wrist movement.
on the dimensions and the degrees of freedom of the robot. This is an important feature of a robot as it determines the strength and the speed of the robot. This also determines the range of applications which can be handled by the robot. (www.mobilerobots.com/researchrobots.aspx, 2012)There are basically three anatomies for the work volume of a robot namely the planar, polar and cylindrical.
The Robot Drive System
The robot drive system determines the speed of the robot and the range of the applications suited for the robots. The cost of the drive also determines their choice in a particular robot. The comparison of the three types of drive system is given in the following table below and also given in the next figure is the cost of the drives.
Table 1 shows the comparison of the robot drive system
Figure 3 Gives the comparison of the cost of the robots drive system.
The Grippers
The grippers are the end effectors which are used to grasp and hold objects. These are used in handling the parts which are moved by the robots.( www.robots.com, 2011) There can be different mechanisms which are used for the purpose of this purpose:
1. Mechanical Grippers
2. Adhesive Grippers
3. Hooks, scoops etc.
4. Vacuum Cups
5. Magnetic grippers: These are easy to control but require a constant source of dc supply. The following figure shows an example of a gripper called venture which is a kind of suction cup.
Figure: 4 Gripper called venture
The sensors
The sensors are important to the functioning of the robots which form the backbone of the feedback control systems. The basic types of sensors are as follows:
1. Tactile sensors
2. Proximity and range sensors
3. Miscellaneous types
4. Machine Vision
The Robot specifications
Figure 5 give the specifications for the robot described in study.
References
1. Mandar Harshe, Colin Menezes and Bhushan Walzade 2009,
An innovative Multi-DOF Robotic ARM Assembly for Press Shops by
2. Research Robots For universities and defense robots , viewed on 14th may 2012
< www.mobilerobots.com/researchrobots.aspx>
3. Industrial Robots News and Advice., viewed on 15th may 2012 <www.robots.com/blog>
4. Understanding Robot Specifications, viewed on 15th may 2012, < www.robots.com › … › Corporate News › Buying A Robot News>
5.Craig John J 2008, Introduction To Robotics:Mechanics and Control , 3/E
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