AUTOMATIC GUIDED VEHICLES AND ROBOTS

AUTOMATIC GUIDED VEHICLES

Anautomated guided vehicleorautomatic guided vehicle(AGV) is a mobilerobotthat follows markers or wires in the floor, or uses vision or lasers. They are most often used in industrial applications to move materials around a manufacturing facility or a warehouse.

Vehicle Types

  • AGVS Towing Vehicleswere the first type introduced and are still a very popular type today. Towing vehicles can pull a multitude of trailer types and have capacities ranging from 8,000 pounds to 60,000 pounds.
  • AGVS Unit Load Vehiclesare equipped with decks, which permit unit load transportation and often automatic load transfer. The decks can either be lift and lower type, powered or non-powered roller, chain or belt decks or custom decks with multiple compartments.
  • AGVS Pallet Trucksare designed to transport palletized loads to and from floor level; eliminating the need for fixed load stands.
  • AGVS Fork Truckhas the ability to service loads both at floor level and on stands. In some cases these vehicles can also stack loads in rack.
  • Light Load AGVSare vehicles which have capacities in the neighborhood of 500 pounds or less and are used to transport small parts, baskets, or other light loads though a light manufacturing environment. They are designed to operate in areas with limited space.
  • AGVS Assembly Line Vehiclesare an adaptation of the light load AGVS for applications involving serial assembly processes.

Common AGV Applications

Automated Guided Vehicles can be used in a wide variety of applications to transport many different types of material including pallets, rolls, racks, carts, and containers. AGVs excel in applications with the following characteristics:

  • Repetitive movement of materials over a distance
  • Regular delivery of stable loads
  • Medium throughput/volume
  • When on-time delivery is critical and late deliveries are causing inefficiency
  • Operations with at least two shifts
  • Processes where tracking material is important

Raw Material Handling

AGVs are commonly used to transport raw materials such as paper, steel, rubber, metal, and plastic. This includes transporting materials from receiving to the warehouse, and delivering materials directly to production lines.

Work-in-Process Movement

Work-in-Process movement is one of the first applications where automated guided vehicles were used, and includes the repetitive movement of materials throughout the manufacturing process. AGVs can be used to move material from the warehouse to production/processing lines or from one process to another.

Pallet Handling

Pallet handling is an extremely popular application for AGVs as repetitive movement of pallets is very common in manufacturing and distribution facilities. AGVs can move pallets from the palletizer to stretch wrapping to the warehouse/storage and/or to the outbound shipping docks.

Finished Product Handling

Moving finished goods from manufacturing to storage or shipping is the final movement of materials before they are delivered to customers. These movements often require the gentlest material handling because the products are complete and subject to damage from rough handling. Because AGVs operate with precisely controlled navigation and acceleration and deceleration this minimizes the potential for damage making them an excellent choice for this type of application.

Trailer Loading

Automatic loading of trailers is a relatively new application for automated guided vehicles and becoming increasingly popular. AGVs are used to transport and load pallets of finished goods directly into standard, over-the-road trailers without any special dock equipment. AGVs can pick up pallets from conveyors, racking, or staging lanes and deliver them into the trailer in the specified loading pattern.

Roll Handling

AGVs are used to transport rolls in many types of plants including paper mills, converters, printers, newspapers, steel producers, and plastics manufacturers. AGVs can store and stack rolls on the floor, in racking, and can even automatically load printing presses with rolls of paper.

Tow type AVG

AGVS Unit Load Vehicles

AGVS Fork Truck

AGVS Pallet Trucks

Light Load AGVS

ROBOTS

Arobotis anautomaticallyguidedmachine, able to do tasks on its own. Another common characteristic is that by its appearance or movements, a robot often conveys a sense that it hasintentoragencyof its own

The wordrobotcan refer to both physical robots andvirtualsoftware agents, but the latter are usually referred to asbots. There is no consensus on which machines qualify as robots, but there is general agreement among experts and the public that robots tend to do some or all of the following: move around, operate a mechanical limb, sense and manipulate their environment, and exhibit intelligent behavior, especially behavior which mimics humans or other animals.

Industrial robot, as defined by ISO 8373, is "an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications." Most commonly, industrial robots are fixed robotic arms and manipulators used primarily for production and distribution of goods. The term "service robot" is less well-defined. IFR has proposed a tentative definition, "A service robot is a robot which operates semi- or fully autonomously to perform services useful to the well-being of humans and equipment, excluding manufacturing operations."

Robots increased productivity, accuracy, and endurance

Automation increases productivity, improves reliability and reduces the price of goods, such automobiles and electronics.

Some examples of factory robots
  • Car production:Over the last three decades automobile factories have become dominated by robots. A typical factory contains hundreds ofindustrial robotsworking on fully automated production lines, with one robot for every ten human workers. On an automated production line, a vehicle chassis on a conveyor iswelded,glued,paintedand finally assembled at a sequence of robot stations.

An intelligent AGV drops-off goods without needing lines or beacons in the workspace

  • Packaging:Industrial robotsare also used extensively for palletizing and packaging of manufactured goods, for example for rapidly taking drink cartons from the end of a conveyor belt and placing them into boxes, or for loading and unloading machining centers.
  • Electronics:Mass-producedprinted circuit boards(PCBs) are almost exclusively manufactured by pick-and-place robots, typically withSCARAmanipulators, which remove tinyelectronic componentsfrom strips or trays, and place them on to PCBs with great accuracy.Such robots can place hundreds of thousands of components per hour, far out-performing a human in speed, accuracy, and reliability.
  • Automated guided vehicles(AGVs):Mobile robots, following markers or wires in the floor, or using visionor lasers, are used to transport goods around large facilities, such as warehouses, container ports, or hospitals.
  • Early AGV-Style Robotswere limited to tasks that could be accurately defined and had to be performed the same way every time. Very little feedback or intelligence was required, and the robots needed only the most basicexteroceptors(sensors). The limitations of these AGVs are that their paths are not easily altered and they cannot alter their paths if obstacles block them. If one AGV breaks down, it may stop the entire operation.
  • Interim AGV-Technologiesdeveloped that deploy triangulation from beacons or bar code grids for scanning on the floor or ceiling. In most factories, triangulation systems tend to require moderate to high maintenance, such as daily cleaning of all beacons or bar codes. Also, if a tall pallet or large vehicle blocks beacons or a bar code is marred, AGVs may become lost. Often such AGVs are designed to be used in human-free environments.
  • Intelligent AGVs (i-AGVs)such as SpeciMinder,ADAM, Tugand MT 400 with Motivityare designed for people-friendly workspaces. They navigate by recognizing natural features.3D scannersor other means of sensing the environment in two or three dimensions help to eliminate cumulativeerrorsindead-reckoningcalculations of the AGV's current position. Some AGVs can create maps of their environment using scanning lasers withsimultaneous localization and mapping(SLAM) and use those maps to navigate in real time with other path planning and obstacle avoidance algorithms. They are able to operate in complex environments and perform non-repetitive and non-sequential tasks such as transportingphotomasksin a semiconductor lab, specimens in hospitals and goods in warehouses. For dynamic areas, such as warehouses full of pallets, AGVs require additional strategies using three-dimensional sensors such as time-of-flight or stereovision cameras.

Robot Specification

Every industrial robot is defined by certain measurements, weights, and design features. RobotWorx lists robot specifications to help customers determine which model is right for their application and facility.

Learn what robot specifications mean, and you'll be able to select the right robot in notime.

Axis Movement Specifications:

  1. Axes-The individual segments of each robot manipulator are connected with mechanical joints - each serves as an axis of movement. The most common industrial robots have six axes of movement. The number and placement of axes determines the flexibility of each model. Check out ourindustrial robot axes
  2. RobotMotionRange- Much like the joints between bones, robot axes have limits to each movement. Every axis has a specific scope of motion. On a typical specifications sheet, the degree of movement shows up as positiveor negative degree of movement from the center base position of each axis.
  3. Robot Motion Speed- Each axis moves at a different speed. They are listed as degrees traveled per second. Focus on this criterion when you need to match certain speed specifications for your application.
  4. Repeatability-Industrial robots are known for their accuracy. But this ability to return to an exact location again and again,known as a robot's repeatability, can vary with each model. More precision-driven applications will require tighter repeatability figures. Repeatability is listed as a millimeter of alteration plus or minus from the point.

Robot Specifications for Weight:

  1. Payload- The weight capacity of each robot manipulator is its payload. This is a critical specification and includes the tooling weight as well. You can rule out a number of robots with this robot specification category alone.
  2. Robot Mass- Every robot has a specific weight or mass. This number only indicates how much the robot manipulator weighs. It does not include the weight of therobot's controller. This specification may not be quite as important unless you are trying to install your robot on a table or shelf.

Specifications and Work Envelope:

  1. V-Reach- How high can the robot go? A robot's vertical reach specification refers to the height of the robot when it extends upwards from the base. Use this to determine whether or not a model is tall enough for your application and location.
  2. H-Reach- How far can a robot reach? The horizontal reach measures the distance of the fully extended arm- from the base to the wrist. Some applications will require a widerwork envelopewith a big reach, others are satisfied with a contained, short horizontal reach.
  3. Structure- Robots are engineered with different structures. The most common by far is the vertical articulated type, sometimes called a vertical jointed-arm robot. Other structure types include SCARA, Cartesian and parallel kinematic robots.

Accuracy: How close does the robot get to the desired point? When the robot's program instruct the robot to move to a specified point, it does not actaully perform as per specified. The accuracy measrue such variance. That is, the distance between the specified position that a robot is trying to achieve (programming point), and the actual X, Y and Z resultant position of the robot end effector.
Repeatability: The ability of a robot to return repeatedly to a given position. It is the ability of a robotic system or mechanism to repeat the same motion or achieve the same position. Repeatablity is is a measure of the error or variability when repeatedly reaching for a single position. Repeatability is often smaller than accuracy. /
Degree of Freedom (DOF)- Each joint or axis on the robot introduces a degree of freedom. Each DOF can be a slider, rotary, or other type of actuator. The number of DOF that a manipulator possesses thus is the number of independent ways in which a robot arm can move. An industrial robot typically have 5 or 6 degrees of freedom. 3 of the degrees of freedom allow positioning in 3D space (X, Y, Z), while the other 2 or 3 are used for orientation of the end effector (yaw, pitch and roll). 6 degrees of freedom are enough to allow the robot to reach all positions and orientations in 3D space. 5 DOF requires a restriction to 2D space, or else it limits orientations. 5 DOF robots are commonly used for handling tools such as arc welders.
Resolution: The smallest increment of motion or distance that can be detected or controlled by the robotic control system. It is a function of encoder pulses per revolution and drive (e.g. reduction gear) ratio. And it is dependent on the distance between the tool center point and the joint axis.

Envelope: A three-dimensional shape that defines the boundaries that the robot manipulator can reach; also known as reach envelope.
  • Maximum envelope: the envelope that encompasses the maximum designed movements of all robot parts, including the end effector, workpiece and attachments.
  • Restricted envelopeis that portion of the maximum envelope which a robot is restricted by limiting devices.
  • Operating envelope: the restricted envelope that is used by the robot while performing its programmed motions.
Reach: The maximum horizontal distance from the center of the robot base to the end of its wrist.
Maximum Speed: A robot moving at full extension with all joints moving simultaneously in complimentary directions at full speed. The maximum speed is the theoretical values which does not consider under loading condition..
Payload: The maximum payload is the amount of weight carried by the robot manipulator at reduced speed while maintaining rated precision. Nominal payload is measured at maximum speed while maintaining rated preci-sion. These ratings are highly dependent on the size and shape of the payload due to variation in inertia.

ORDER PICKING

Theorder pickingor order preparation operation is one of a logisticwarehouse's process. It consists in taking and collecting articles in a specified quantity before shipment to satisfy customers orders. It is a basic warehousing process and has an important influence onSupply Chain's productivity. This makes order picking one of the most controlled logistic processes. It is one of theWMSfunctionalities.

MAIN TYPES OF ORDER PICKING

  • piece picking or picker to part method: the order picker(s) move(s) to collect the products necessary for one order
  • zone picking method: each order picker is assigned to one specific zone and will only realize order picking within this zone
  • wave picking method: the order picker(s) move(s) to collect the products necessary for several order
  • sorting systems method: no movement of the order picker(s), the products are brought to him by an automatic system (conveyor system, automatic storage ...).
  • pick to box method: no movement of the order picker(s), the picking area is organized so that there are a number of picking stations connected by a conveyor. The order picker fills the box with the products from his station and the box moves to the other picking stations until the customer order is complete.

8 Order Picking Secrets
Automatically verify everything
Design your order picking system to double-verify every step of the picking process. People will make mistakes – that is human nature. But double (or even triple) checking will catch the mistakes – preferably while the picker is still in front of the pick slot, where correction will cost you almost nothing. A system that requires scanning of slot ID bar code labels and product UPC codes, along with a blind entry of the quantity picked, will guarantee the right pick is made.
Touch items once
Touch each piece of product exactly ONCE. The pick process should allow enough verified accuracy that further repacking, QC checking, or shipping checking, is NOT required. A pick unit should go into the outbound truck touched only by the original picker’s hands.
Minimize walking
Minimize selector walking by:
Picking from both sides of the aisle, using small pick facings.
Placing slow-moving items on side aisles which are entered only when needed.
Picking many smaller orders in one trip (batch picking.)

100% product availability
Design your replenishment system to insure a selector never has to face an empty pick slot waiting for replenishment, and that orders never need to be segregated, awaiting missing items before shipping.
Ideally, pick lists should contain only items KNOWN to actually be in stock at the pick slot. It is unproductive to have pickers waste precious time correcting inventory system shortcomings.
Use ABC item analysis
If 10% of your items can completely satisfy 50% of your orders (typically true), then I call these "A" items You can set up a short pick line comprised of only these "A" items, and immediately half of your orders require walking through only 10% of the pick area. Then, find another 20% of your items that will satisfy an additional 30% of orders, and slot them as branches off the short pick line.
Almost 80% of your orders will now require travel passing in front of only 15-20% of your total pick slots!
Stop pick and pass line picking
"Pass-along" picking (passing totes along a conveyor line from picker to picker), slows all orders to the speed of the slowest picker, or, to the capacity of the busiest pick station. Pick rates of the better pickers can often be increased by 30% to 200%, just by switching from conveyor picking to individual cart picks.
Invest in training and quality circles
No matter how well designed your picking system WAS, changing customer requirements will undermine its original excellence. Your pickers and supervisors are your first line of defense against "creeping obsolescence." An investment in productivity and accuracy improvement (Total Quality), and management supported quality circles that meet regularly to identify problems and propose solutions, will pay big dividends in continuous improvement of even an already excellent system.
Walk your talk
In my experience, the least costly, most effective way to improve your distribution system is through direct, continuous and enthusiastic top and middle management support, of the workers’ striving for the highest level of picking accuracy and efficiency. Workers sense immediately, if management is only giving "lip service" to their commitment to excellence. Caring is contagious.