Download Peripheral Systems

Peripheral Systems
What is a Peripheral System?
• A system or equipment that performs tasks related to or involving the
robot, but that is not part of the robot.
• Capable of functioning without the robot.
• Anything that is not part of the core system, such as options or
additions.
• Core system consists of the robot, controller, teach pendant, built-in
sensors, and power supply.
• The robot could work without peripherals.
Safety Systems
• A common peripheral in the robotic world.
• It falls to the company that is buying a robot to ensure that the proper
safety protocols and equipment are in place.
• The safety devices that are a part of the robot or built into the robot are
considered a part of the core system.
• The E-stop on the teach pendant or robot controller are not counted as
part of the safety peripheral system, as they are built-in safety features of
the core robotic system.
Positioners
• This device manipulates the position of the parts that the robot is
working with and has nothing to do with the physical position of the
robot.
• Used to rotate parts, swap finished parts with raw parts, secure parts
during processing operations, and complete other tasks that assist in the
process of producing goods.
• Commonly used for swapping of raw parts for finished parts – the
system will have a rotary platform with all the appropriate fixturing and
clamps installed on it – the operator will put the raw parts in one set of
fixtures, lock them in place, and then press an indicator button that
sends a signal to the system controller that the parts are ready – when
the system is ready to process parts, the positioner will rotate the raw
parts into the work zone and, at the same time, rotate out the other
fixture for the operator to remove finished parts and refill with raw
parts.
• Mobile robot base – robot is attached to this positioner, and it moves
the entire robot from point A to point B, with optional stops in
between, to assist the robot in performance of tasks.
• Mobile robot bases are used so that robots can keep up with moving
parts on chains and conveyors, feed multiple machines in an area, move
parts to and from warehouses, and carry out other tasks where the robot
needs to cover an area larger than its work envelope.
• Peripheral positioning systems add flexibility and create options that the
robot would have otherwise.
• Often referred to as external axes because they link to the robot
controller, the system stores positional data for them, and we can
program them as we would other axes.
End-of-Arm Tooling Peripheral Systems
• EOAT is an add-on to the robot requiring a power source and data
input
• Robot tool-changing peripheral systems – basic principle is to move the
desired tooling into position for exchange with the tooling the robot is
currently using – the robot puts the current tooling into an empty slot,
that was presented by the positioner, and then releases the tooling via a
coupling mechanism – once the robot is clear, the positioner will index
the required tooling into position and wait for the robot to connect the
quick release to the tooling – once it makes a positive connection, the
robot carefully removes the tooling from the positioner, and it’s back to
work for the robot.
• Welding – systems to clean the welding gun tip of any slag or stray
pieces of melted metal that might accumulate
• Drilling – sensors to ensure that the drill bit has not broken or worn
down beyond a set point
• Spray nozzles – clean-up devices to ensure that they do not clog up
between uses or to clean out one fluid before using a different fluid
• Quality of parts – force sensors and measurement systems to help
determine the quality of parts
• The peripheral system that goes with the tooling may perform tasks
such as drilling, reaming, polishing, or other finishing actions.
• Robot using a peripheral motor with a drill attached to perform tasks –
saves time in the production process and eliminates the need for extra
equipment by having the robot perform part of the production process
– when external motors are used in this way, the data that the system
monitors is usually the amount of torque or amperage that the motor is
using as well as the speed of rotation
What is a Work Cell?
• A logical grouping of machines that perform various operations on parts
in a logical order during the production process.
• These machines work independently of one another, but share
information – located in close proximity to enhance the production
process by creating a smooth, efficient workflow.
• Work cells are part of lean manufacturing, which focuses on cutting
production costs by minimizing wasted time and materials so that U.S.
industry can compete with countries that make products more cheaply
than we do.
• Work cells are groupings of standalone systems, machines, and
auxiliary equipment all working together and often they utilize robots
for material handling and other operations.
• The cells may be as simple as a welding robot, positioner, welding gun
tip cleaner, and an operator or they may consist of a welding robot, a
machine that removes materials from raw cast parts, a conveyor that
connects this machine to the welder, and another conveyor that takes
the welded parts to a robot that picks them up and uses a pedestal
grinder to buff and shape parts after a camera does a visual inspection.
• Often work cells are complex setups consisting of multiple machines all
working to process parts.
• The work cell demonstrates the difference between a standalone
machine and a peripheral system.
• Many companies have spent thousands of dollars creating, setting up,
and tweaking their work cells to reduce the number of times that they
handle the parts, how far parts travel between operations, and how long
it takes to process the parts – all of these reductions represent a
reduction in the overall cost of parts, saving both manufacturer and
customer.
Nonindustrial Peripherals
• They augment the operation of the robot but are not part of the core
system
• Charging stations – some robots find these systems by tracking the
location, others can follow a signal home when in need of refuel
(Roomba and Lawnbot)
• Many of these systems are designed so that various equipment can be
added or removed to customize the robot in the same way tooling is
swapped in industry
• A robotic company can manufacture a large number of just a few types
of robots (base models), which reduces production costs and gives the
customers the options they need to get the robot they want.
System Communications
• Worst-case scenario is where some signals make it through while others
are lost, creating intermittent operation and functionality that can
become erratic and unpredictable.
• Digital signals have exactly two states, on or off, which translate as 1 or 0
in the binary code. We base these signals on a set voltage or amperage
level when they are based on real-world equipment and not just data in
the system.
• Analog signals are a range of voltage or amperage that correlate to a set
scale used to express changing values in the sensors and output devices.
• Digital signals indicate the presence or absence of things with sensors
like prox switches and limit switches, or any other place where a yes or
no answer will do.
• Analog signals come in handy when we need to monitor ranges of data,
such as the temperature of a room, the distance between the robot and
an object, or how full a tank of liquid is.
• Getting the signal from sensors, machines, and peripheral systems can
be done by bringing the signal directly to the robot via wire. It can also
be done by the RS232 standard. (direct communication)
• The RS232 standard is a communication standard where certain wires
are designated to transmit specific signals.
• This set up a specific way for two controllers to share data, allowing for
large amounts of data to pass quickly back and forth. The downside
was the need for more controllers and the specific hardware to make
this happen.
• RS232 was a standard, not a set law or rule. It used the nine-pin serial
port, which is no longer standard on computers.
• USB communication cables have replaced the RS232 communication.
• A second for system communication is via a network.
• Networking is where two or more systems share information over some
form of connection.
• Hardwired systems require a communication cable or wires between the
devices that need to talk, whereas wireless networks only need a device
or card that works similar to a Bluetooth device to communicate.