How Does a Robotic Arm Work?
A robotic manipulator arm is one of the main parts of an industrial robot. It is a mechanical arm that can be programmed to perform a variety of production related tasks. Each robotic arm contains several segments that are attached together by joints also referred to as axes. Each joint contains a step motor that allows the robotic arm to complete a specific motion. The more joints or axes a robotic arm has the greater its range of motion. Robotic arms are able to operate in precise movements with high repetition because of their motorized axes. Step motors allow each axis to move in exact increments for incredible accuracy.
There are many different configurations of robotic arms. The most common type is the six-axis articulated arm. This type of robotic arm closely resembles the human arm in both its appearance and movements. It is made up of seven segments with six axes. Six-axis robotic arms have a shoulder, elbow, and wrist just like a human. The FANUC M10ia is an example of a six-axis robotic arm.
Articulated robotic arms are responsible for positioning the industrial robot to access workpieces. A six-axis robotic arm has six degrees of freedom allowing it to move in six different directions for greater flexibility. All robotic arms have a certain amount of space they can operate in, which is known as their work envelope. The work envelope of a robotic arm is defined by its reach and axes. The longer the reach and the more axes a robotic arm has the wider its work envelope. The FANUC M710ic/20L is a six-axis robot with an extended reach, making it ideal for covering large work areas. Most industrial robotic arms operate in a spherical work envelope.
Robotic arms are also responsible for controlling the end-effector. The end-effector is the device attached to the wrist of the robotic arm that interacts directly with workpieces. There are many different types of end-effectors that can be integrated with robotic arms. These include grippers, welding torches, drills, sprayers, and cutters. During operation the robotic arm will position its self to access workpieces and then execute the movements of the end-effector to complete a task. For example, a ABB 2600-12 integrated with a gripper for automated material handling will position its arm over the part, lower its arm towards the part, open and close the gripper around the part, and then move the part to a conveyor.
In order to be able to perform manufacturing applications, robotic arms must be programmed. This is typically done through a controller and teach pendant. To start, an operator will enter the program instructions through the teach pendant. The coded application instructions are sent to the controller which then interprets the application program and communicates the steps to the robot’s CPU. The CPU processes the program code and guides the robotic arm through the application. Some robotic arms can be programmed through manual movement. This is a common feature of collaborative robots. The arm of the FANUC Cr15ia can be programmed by this method. Robotic arms are capable of being programmed for a variety of applications ranging from assembly to welding to even inspection.