Robotic Arms and Robotics

The word robot comes from the Czech word "robota", meaning "forced labor." The stuff of science fiction robotics in the 21st century is different than your parents or your grandparents’ ideas of robotics. What used to be thought of as futuristic improbability is now becoming a reality.

There are, theoretically, three Laws of Robotics. The Laws of Robotics were developed by a small group of scientists who believe that robotics is the wave of the future. The first law, referred to as law zero, is that a robot may not injure humanity, or, though inaction, allow humanity to come to harm. The second law states that a robot may not injure a human being, or, through inaction, allow a human being to come to harm, unless this would violate a higher order law. This law was created so that mankind would seek not to create robots that would harm people. The third law is that a robot must obey orders given it by human beings, except where such orders would conflict with a higher order law. And finally the final law is that a robot must protect its own existence as long as such protection does not conflict with a higher order law. These were used in a recent Hollywood movie however many people don’t know that the Laws of Robotics actually exists.

According to The Robot Institute of America a robot is a “reprogrammable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks." This is a scientific sounding description however most people just think of robots as machine that mimic their counterparts. In practical usage, a robot is a mechanical device which performs automated tasks.

The most developed robot in practical use today is the robotic arm and it is seen in applications throughout the world. We use robotic arms to carry out dangerous work such as when dealing with hazardous materials. We use robotic arms to carry out work in outer space where man can not survive and we use robotic arms to do work in the medical field such as conducting experiments without exposing the researcher.

Some of the most advanced robotic arms have such amenities as a rotating base, pivoting shoulder, pivoting elbow, rotating wrist and gripper fingers. All of these amenities allow the robotic arm to do work that closely resembles what a man can do only without the risk.

Linear Motors and Stepper Motors

A linear induction motor is made up of an inductor which is made of individual cores with a concentrated polyphase. Linear motors can be directly substituted for ball screw drives, hydraulic drives, pneumatic drives, or cam drives.

A linear induction motor is basically what is referred to by experts as a “rotating squirrel cage” induction motor. The difference is that the motor is opened out flat. Instead of producing rotary torque from a cylindrical machine it produces linear force from a flat machine. The shape and the way it produces motion is changed, however it is still the same as its cylindrical counterpart. There are no moving parts, however and most experts don’t like that. It does have a silent operation and reduced maintenance as well as a compact size, which appeals many engineers. There is also a universal agreement that it has an ease of control and installation. These are all important considerations when thinking about what type of device you want to create. The linear induction motor thrusts ratio varies depending mainly on the size and rating. Speeds of the linear induction motor vary from zero to many meters per second. Speed can be controlled. Stopping, starting and reversing are all easy. Linear induction motors are improving constantly and with improved control, lower life cycle cost, reduced maintenance and higher performance they are becoming the choice of the experts. Linear motors are simple to control and easy to use. They have a fast response and high acceleration. Their speed is not dependant on contact friction so it is easier to pick up speed quickly.

Stepper motors are a special kind of motor that moves in discrete steps. When one set of windings is energized the motor moves a step in one direction and when another set of windings is energized the motor moves a step in the other direction. The advantage of stepper motors that the position of the motor is "known". Zero position can be determined, if the original position is known.

Stepping motors come in a wide range of angular resolution and the coarsest motors typically turn 90 degrees per step. High resolution permanent magnet motors are only able to handle about 18 degrees less than that. With the right controller stepper motors can be run in half-steps, which is amazing.

The main complaint about the stepper motor is that it usually draws more power than a standard DC motor and maneuvering is also difficult.

Linear Actuators and Linear Motion

Mechanical energy is an area of science that is making strides every day. The study of how actuators produce mechanical motion by converting various forms of energy into mechanical energy is a source of great exploration. Science finds new ways to make use of actuators every day including for medical purposes. Many scientists believe that the more they study these seemingly simple machines, the more they will discover ways of helping mankind.

The way in which a linear actuator works is that there is a motor that rotates a drive screw using a synchronous timing belt drive. Some linear actuators can also use a worm gear drive or direct drive. Which ever the choice, the turning of the screw pushes a drive nut along the screw, which in turn pushes the rod out and the rotating the screw in the opposite direction will retract the rod. According to the Association of Sciences, the drive screw is either an ACME or ball thread or is belt-driven which is what gives the machine its motion. A cover tube protects the screw nut from environmental elements and contamination thus allowing for the machines use continually without the chance of it getting gummed up. Radial thrust bearings permit the screw to rotate freely under loaded conditions and gives the linear actuator its strength.

Linear actuators usually serve as part of motion control systems. These days most are run by computers. Control systems, a device that you find linear actuators in, move or control objects. This is made possible by the actuators.

There are various forms of energy that run actuators. These forms of energy include, hydraulic, pneumatic, mechanical and electrical. Linear actuators are used a lot in robotics and factory automation.

Linear motion is when an object moves in a straight line. This is the basic concept that drives the linear actuator. One has to stop and consider when choosing a linear actuator which type they need to fit the purpose of their project. Some things to keep in mind are the speed, stroke length and load rating of the actuator. Programmability of the actuator is also a factor especially when the application will be one that requires specialized detail. A linear actuator can be used in just about any forum. Ask yourself some questions when attempting to choose the right one for your project such as are there particular safety mechanisms required, environmental concerns to be addressed or space issues?