Robots
The controller can be made from mechanically operated drums that step through a sequence of events. This type of controller operates with a very simple robotic system. The controllers found on the majority of robotic systems are more complex devices and represent state-of-the-art electronics. That is, they are microprocessor-operated. These microprocessors are either 8-bit, 16-bit, or 32-bit processors. This power allows the controller to be very flexible in its operation.
The controller can send electric signals over communication lines that allow it to talk with the various axes of manipulator. This two-way communication between the robot manipulator and the controller maintains a constant update of the location and the operation of the system. The controller also controls any tooling placed on the end of the robot’s wrist.
The controller also has the job of communicating with the different plant computers . The communication link establishes the robot as part of a computer-assisted manufacturing (CAM) system.
As the basic definition stated , the robot is a reprogrammable , multifunctional manipulator . Therefore , the controller must contain some type of memory storage . The microprocessor-based systems operate in conjunction with solid-state memory devices . These memory devices may be magnetic bubbles , random-access memory , floppy disks , or magnetic tape . Each memory storage device stores program information for later recall or for editing .
C. Power supply
The power supply is the unit that supplies power to the controller and the manipulator . Two types of power are delivered to the robotic system . One type of power is the AC power for operation of the controller . The other type of power is used for driving the various axes of the manipulator . For example , if the robot manipulator id controlled by hydraulic or pneumatic manipulator drives , control signals are sent to these devices , causing motion of the robot .
For each robotic system , power is required to operate the manipulator . This power can be developed from either a hydraulic power source , a pneumatic power source , or an electric power source , These power sources are part of the total components of the robotic work cell .
The industrial robot is used in the manufacturing environment to increase productivity . It can be used to do routine and tedious assembly line jobs , or it can perform jobs that might be hazardous to do routine and tedious assembly line jobs , or it can perform jobs that might be hazardous to the human worker . For example , one of the first industrial robots was used to replace the nuclear fuel rods in nuclear power plants . A human doing this job might be exposed to harmful amounts of radiation . The industrial robot can also operate on the assembly line , putting together small components , such as placing electronic components on a printed circuit board . Thus , the human worker can be relieved of the routine operation of this tedious task . Robots can also be programmed to defuse bombs , to serve the handicapped , and to perform functions in numerous applications in our society .
The robot can be thought of as a machine that will move an end-of-arm tool , sensor , and gripper to a preprogrammed location . When the robot arrives at this location , it will perform some sort of task . This task could be welding , sealing , machine loading , machine unloading , or a host of assembly jobs . Generally , this work can be accomplished without the involvement of a human being , except for programming and for turning the system on and off .
The basic terminology of robotic systems is introduced in the following :
1. A robot is a reprogrammable , multifunctional manipulator designed to move parts , materials , tools , or special devices through variable programmed motions for the performance of a variety of different task . This basic definition leads to other definitions , presented in the following paragraphs , that give a complete picture of a robotic system .
2. Preprogrammed locations are paths that the robot must follow to accomplish work . At some of these locations , the robot will stop and perform some operation , such as assembly of parts , spray painting , or welding . These preprogrammed locations are stored in the robot’s memory and are recalled later for continuous operation . Furthermore , these preprogrammed locations , as well as other program data , can be changed later as the work requirements change . Thus , with regard to this programming feature , an industrial robot is very much like a computer , where data can be stored and later recalled and edited .
3. The manipulator is the arm of the robot . It allows the robot to bend , reach , and twist . This movement is provided by the manipulator’s axes , also called the degrees of freedom of the robot . A robot can have from 3 to 16 axes . The term degrees of freedom of freedom will always relate to the number of axes found on a robot .
4. The tooling and grippers are not part of the robotic system itself ; rather , they are attachments that fit on the end of the robot’s arm . These attachments connected to the end of the robot’s arm allow the robot to lift parts , spot-weld , paint , arc-weld , drill , deburr , and do a variety of tasks , depending on what is required of the robot .
5. The robotic system can also control the work cell of the operating robot . the work cell of the robot is the total environment in which the robot must perform its task . Included within this cell may be the controller , the robot manipulator , a work table , safety features , or a conveyor . All the equipment that is required in order for the robot to do its job is included in the work cell . In addition , signals from outside devices can communicate with the robot in order to tell the robot when it should assemble parts , pick up parts , or unload parts to a conveyor .
The robotic system has three basic components : the manipulator , the controller , and the power source .
A . Manipulator
The manipulator , which does the physical work of the robotic system , consists of two sections : the mechanical section and the attached appendage . The manipulator also has a base to which the appendages are attached . Fig.1 illustrates the connection of the base and the appendage of a robot .
The base of the manipulator is usually fixed to the floor of the work area .Sometimes , though , the base may be movable . In this case , the base is attached to either a rail or a track , allowing the manipulator to be moved from one location to another .
As mentioned previously , the appendage extends from the base of the robot . The appendage is the arm of the robot . It can be either a straight , movable arm or a jointed arm . the jointed arm is also known as an articulated arm .
The appendages of the robot manipulator give the manipulator its various axes of motion . These axes are attached to a fixed base , which , in turn , is secured to a mounting . This mounting ensures that the manipulator will remain in one location。
At the end of the arm , a wrist is connected . The wrist is made up of additional axes and a wrist flange . The wrist flange allows the robot user to connect different tooling to the wrist for different jobs .
The manipulator’s axes allow it to perform work within a certain area . This area is called the work cell of the robot , and its size corresponds to the size of the manipulator . Fig.2 illustrates the work cell of a typical assembly robot . As the robot’s physical size increases , the size of the work cell must also increase .
The movement of the manipulator is controlled by actuators , or drive systems . The actuators , or drive system , allows the various axes to move within the work cell . The drive system can use electric , hydraulic , or pneumatic power . The energy developed by the drive system is converted to mechanical power by various mechanical drive systems .The drive systems are coupled through mechanical linkages .These linkages, in turn , drive the different axes of the robot . The mechanical linkages may be composed of chains , gears ,and ball screws.
B. Controller
The controller in the robotic system is the heart of the operation. The controller stores preprogrammed information for later recall, control peripheral devices, and communicates with computers within the plant for constant updates in production
The controllers is used to control the robot manipulator’s movements as well as to control peripheral components within the work cell. The user can program the movements of the manipulator into the controller through the use of a hand-held teach pendent. This information is stored in the memory of the controller for later recall. The controller stores all program data of the robotic system. It can store several different programs, and any of these programs can be edited.
The controller is also required to communicate with peripheral equipment within the work cell. For example, the controller has an input line that identifies when a machining operation is completed. When the machine cycle is completed, the input line turns on, telling the controller to position the manipulator so that it can pick up the finished part. Then, a new part is picked up by the manipulator and placed into the machine. Next, the controller signals the machine to start operation.