Controllers, Operating Systems, Motion Control, and Robot Dynamics
After successfully creating a project in VEXcode V5 to move the arm mounted on the Workcell, it is time to examine things closer and relate them to the industrial robots used in manufacturing. In this reading you will explore the following topics: a manufacturing robot’s controller, operating systems, motion control, and robot dynamics.
Industrial robots utilize multiple coordinate systems (frames) in their movements. The robot’s position is measured either by the position of its wrist with respect to its world/base coordinate system (world/base coordinates) or by the angular position of each joint (joint coordinates). Each joint of the robot has a specific range limited by a mechanical stop/switch marking the end points of the joints motions. This can also be reduced using software settings.
The V5 Brain is the controller for the V5 Workcell. Controllers receive inputs, process the information, and then provide outputs. The Brain receives inputs. An example is the Bumper Switch sensor (acting as an E-stop for the Workcell) provides input to the brain when it is pressed.
The sensors for the Brain can provide a digital input. A digital input is a signal that is either off or on, like the Bumper Switch. Sensors like the potentiometers, which help control the motor shafts on the robot’s arm, provide an analog input. This type of input provides a range of values for the brain. Other sensors like optical sensors can provide a complex input signal for the brain.
The Brain can also receive input communication through its USB programming port from a programming device like a laptop. When the Brain is equipped with a V5 Radio, it can also receive its programming input wirelessly.
The Brain takes the inputs and processes this information using the user program and operating system’s coded instructions to have the brain’s electronic processors, memory, and clocks work together and produce an output. The Brain’s operating system is also known as firmware. This is a lower level set of software which allows the user program to communicate with the robot’s hardware.
Industrial Robot Controllers and Operating Systems
There are numerous manufacturers of industrial robots such as FANUC, Yaskawa, ABB, and KUKA. These companies often have their own robot controllers and robot operating systems. Even though these controllers may look very different than the V5 Brain, the principles are exactly the same. They receive input from digital sensors, analog sensors, vision sensors and teaching pendants. They can receive user created programs. They can communicate through a direct cable connection and some can communicate wirelessly.
These industrial robot controllers take their inputs and process the information using an user program and the operating system’s coded instructions to have their electronic processors, memory, and clocks provide outputs.
The controller provides the outputs to control the robot’s actuators. The actuators may be hydraulic, pneumatic, or electric. However, the output from the controller is still what causes them to make the robotic arm move.
In addition, the different operating systems of industrial robots function the same as the Brain’s firmware. Their operating system is a lower level set of software which allows the user program to communicate with the robot’s hardware.