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ROBOTIC ARM & ITS DESIGN
'An industrial robot is a reprogrammable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks.'
8.1 Physical Medicine & Rehabilitation-A brief History
For centuries man used such natural physical agents as hot springs and sunlight to treat his ailments, but the development of physical medicine as a specialized medical service took place largely after World War I. Two factors influenced its growth in the 20th century-epidemic poliomyelitis and the two world wars-both of which created large numbers of young, seriously handicapped persons. Physical medicine was definitively established through the American physician Howard A. Rusk's efforts to rehabilitate wounded soldiers during and after World War II. Physical medicine then became available for the treatment of patients with such diverse problems as fractures, burns, tuberculosis, painful backs, strokes, nerve and spinal cord injuries, diabetes, birth defects, arthritis, and vision and speech impairments. Physical medicine is closely associated with orthopedic surgery, but it is also prescribed by physicians and surgeons in all branches of medicine. Physicians who specialize in physical medicine are called physiatrists.
The objectives of physical medicine are relief of pain, improvement or maintenance of functions such as strength and mobility, training in the most effective method of performing essential activities, and testing of function in various areas. Tests cover such fields as muscle strength, degree of joint mobility, breathing capacity, and muscular coordination.
The therapeutic means most commonly employed include heat, massage, exercise, electrical currents, and functional training. Since the 1970s these basic means have been supplemented and enhanced by psychological counseling, occupational therapy, and a variety of other treatments which may be used in concert to help the disabled person achieve the fullest possible life despite the persistence of his medical problem.
Heat is used generally to stimulate circulation and to relieve pain in the area treated. It may be applied by infrared lamps, shortwave radiation, or high-frequency electrical currents (diathermy); by hot, moist compresses or immersion in hot water (hydrotherapy); or by ultrasound. Massage primarily aids circulation and relieves local pain or muscle spasm.
Exercise, the most varied and widely used of all physical treatments, is usually designed to do one or more of three things: increase the amount of motion in a joint, increase the strength in muscle, or train a muscle to contract and relax in useful coordination with other muscles. In addition to its obvious use following stiffness or paralysis, exercise may be used to improve the breathing of patients with lung disorders, assist circulation, relax tense muscles, and correct faulty posture.
In the late 20th century high technology was increasingly harnessed in efforts to rehabilitate paraplegics, quadriplegics, and others with severely impaired motor functions. Microcomputers were developed that could send precisely coordinated jolts of electricity directly into the muscles of such patients, mimicking the cerebral impulses that could no longer reach their muscle destinations because of a severed spinal cord. The microcomputers' sophisticated programs enable them to contract a patient's muscles in unison so that he can actually stand and sit, walk, and even use his hands to perform relatively fine movements. Such devices were still in the experimental stage and were costly to make and use, but they seemed to be the most promising development yet in efforts to restore the power of movement to nerve injury victims.
Other, less ambitious devices to help paralyzed patients include wheelchairs with specially equipped control systems that can be operated by the mouth and teeth movements of a quadriplegic. Mobile robotic arms have been developed that are equipped witha video camera so that they can move safely and intelligently about a patient's house. These personal robots can receive and execute oral commands from the patient to perform such simple household tasks as filling a glass with water or taking a book off a shelf.
Functional training teaches the impaired individual how to carry out most safely and effectively the activities of daily life. This training may mean learning to use crutches, a brace, or an artificial arm; or it may involve working out and practicing the movements required to do housework with the use of only one hand or the way to board public transportation with a stiff leg. Such training often requires long hours of practice; it may be facilitated by use of devices that make it easier to fasten buttons, hold a fork, or dial a telephone.
Physical medicine and rehabilitation underwent a rapid expansion during the late 20th century, largely because of the development of antibiotics and other fundamental advances in modern medicine, which not only save the lives of many who would not have survived illness or injury in earlier decades but also prolong life in general.
8.2 THE ROBOT MANIPULATOR:
The technology of robotics is concerned with the design of the mechanical manipulator and the computer systems used to control it. It is also concerned with the industrial applications of robots, which are described below.
The mechanical manipulator of an industrial robot is made up of a sequence of link and joint combinations. The links are the rigid members connecting the joints. The joints (also called axes) are the movable components of the robot that cause relative motion between adjacent links. As shown in Figure 8.1, there are five principal types of mechanical joints used to construct the manipulator. Two of the joints are linear, in which the relative motion between adjacent links is translational, and three are rotary types, in which the relative motion involves rotation between links.
The manipulator can be divided into two sections: (1) an arm-and-body, which usually consists of three joints connected by large links, and (2) a wrist, consisting of two or three compact joints. Attached to the wrist is a gripper to grasp a work part or a tool (e.g., a spot-welding gun) to perform a process. The two manipulator sections have different functions: the arm-and-body is used to move and position parts or tools in the robot's work space, while the wrist is used to orient the parts or tools at the work location. The arm-and-body section of most commercial robots is based on one of four configurations. Each of the anatomies, as they are sometimes called, provides a different work envelope (i.e., the space that can be reached by the robot's arm) and is suited to different types of applications.
Five types of mechanical joints used in robot manipulators. Collinear and orthogonal are translational joints; rotational, twisting, and revolving are rotary joints.
8.3 Robotic Arm-Its Design
Robotic Arm is made of laser cut tough lexan components.First of all,I have drilled the servo horns with a 1/16" drill in the indicated positions.Then assembled the forearm structure using eight of rivet fasteners to hold the servos in place.The arm finally made was mounted to one of the optional rotating bases or a mobile robot.The rivet fasteners are used for this purpose.