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ROBOTIC RESOURCES

KEBA Introduces “Look Ahead Path Planning” to Increase Productivity of Pick & Place Applications in the Packaging Industry

KEBA Corporation

Robotic pick & place applications are booming with no end in sight.  Compared with fixed machine concepts, engineers can use robotics to increase productivity and flexibility, while at the same time reducing costs.  So what are the challenges facing control system suppliers, and how has the Austrian automation specialist optimized KeMotion Packaging, its robotic packaging solution, in this respect?

The benchmark for pick & place applications in the packaging industry

Figure 1: Typical pick & place situation with several robots in a shared workspace and two opposing conveyor belts The productivity benchmark for automated pick & place is the number of products that can be successfully picked up and placed in a target position per minute.

To achieve the best possible results, pick & place robots must operate as efficiently as possible and avoid idle time.  This topic becomes even more critical with multiple robots operating in a shared workspace.

The innovative approach from KEBA

New technology from KEBA makes it possible to achieve a more productive and flexible pick & place system, with lower maintenance and energy costs.  This is possible thanks to KEBA’s new “Look Ahead Path Planning” feature for multiple robots operating in a shared workspace.

The general principle of this new feature is to pick & place the highest number of products per minute, while at the same time only moving “as fast as necessary”.  This means using vision systems, advanced algorithms, and multi-robot control to look at products moving down a conveyor belt, take into account the position and workspace of each robot, and intelligently plan the movement of each robot to maximize productivity and minimize mechanical stress on the system.

Familiar problems with conventional robotic pick & place systems

"Stop & go" operation: In a typical multi-robot pick & place system, shared workspace is blocked as a robot enters the space.  Abrupt braking followed by fast accelerations result as additional robots wait and enter the shared space.  The end result is limited productivity, increased stress on the robot’s mechanical elements, and increased energy consumption.  The risk of production stoppage increases with the additional mechanical stress, and at minimum more scheduled maintenance is required.

Lost time: Idle time is anathema to productivity, especially in the case of robots. Constant "stop & go" in a typical pick & place system has a negative impact on performance. To continue with the planned path, the robot always has to accelerate out of inactivity, which costs valuable time and energy.
 
Figure 2: Limitation of the effective workspace is the result of multiplying time t by conveyor belt speed v. Time t is the duration of motion from place to pick position.Limited workspace: Lack of path planning also limits the effective workspace and therefore productivity of each robot in a typical pick & place system.  In these systems, the robot cannot approach the object that is to be picked up until the object enters the robot’s defined workspace. As the object enters the workspace, the robot starts moving to the pick location.  During this time the object continues moving along the conveyor belt, which can ultimately limit the effective workspace usage to less than half of what is theoretically available (figure 2). As a result, the maximum number of products on the conveyor is limited, and the buffer volume is restricted.  In some cases the use of additional robots is required to achieve the desired throughput.

Help from KeMotion thanks to “Look Ahead Path Planning”

KEBA precisely took on these challenges when it added the Look Ahead Path Planning feature to its established KeMotion Packaging system for packaging robots.

Foreign objects are now included in the path planning, which includes other robots and products moving on a conveyor belt. Look Ahead Path Planning enables the KeMotion system to automatically react to upcoming events and use the most intelligent strategy to increase productivity.  This feature is designed to be easy to use without the need for additional programming.

Figure 3: Thanks to "Look Ahead Path Planning", foreign objects such as products on a conveyor and other robots are taken into account in the real-time path planning.  The result is higher productivity and less cost.Only a good control system knows when each robot will be where

KAIRO, the easy to use robot programming environment from KEBA, is interpreted online in the KeMotion control system. Up to 30 program lines are planned in advance, which means the control system can say exactly where a robot will be seconds before its tool center point actually reaches the position. In addition, speed and acceleration are taken into account to avoid undesired peaks in the dynamic process of individual robot axes.  Any changes in motion paths required for external events, such as machine stopping or tracking, takes place in the interpolation cycle.

Look Ahead Path Planning enhances this already sophisticated planning by taking into account foreign objects, such as other robots and products on a conveyor belt.  Higher productivity with less mechanical stress and less energy consumption are achieved as a result of integrating the timing of these foreign objects into the path planning.

A real world example shows the principle quite clearly:

Figure 4. You adjust your speed to avoid the other car and pass through the intersection at the desired speed.  There is no need to come to a complete stop unless necessary for an emergency.You are approaching a yield sign while driving in your car.  Another car is on the crossroad driving through the intersection.  You can see that the other car is alone, and there are no additional cars or pedestrians within close range of the crossing.

Thanks to this information, you can adjust your speed to avoid the car in the intersection and pass through at the desired speed.  Since you do not come to a complete stop, you save time and have less extreme deceleration and acceleration, therefore saving fuel and reducing mechanical stress on your braking system and overall car.

You always have an eye on the intersection and surrounding area, so you are always in a position to brake in an emergency – for example if the other car stops suddenly in the middle of the crossing.  But for most situations, the results are maximum speed and less wear and tear.

If we transfer this to two robots working in a shared workspace, this means that one robot tells the other how long it will remain in the shared area. The second robot automatically optimizes its path speed based on this information.  If we take it one step further to a pick & place application, it also means that the KeMotion control system knows when products on a conveyor belt will reach the robot's workspace. Based on the current position of the robot, its speed toward the product is optimized so that it is picked as early as possible when it actually enters the robot's workspace. As a result, the robot takes full advanced of the workspace, and throughput is increased.

Better performance, smoother movements, lower energy consumption

In pick & place applications with unstructured product flow, robots are constantly confronted with random idle time. The Look Ahead Path Planning feature from KEBA provides an ingenious solution to this challenge, resulting in significantly increased throughput and performance, less maintenance, and less energy consumption.

In addition, the robot's workspace is maximized through look ahead calculation of the robot's path. Products are picked at the earliest possible time, and the robot can efficiently compensate for fluctuations in product flow.

In live operation you can see clearly with the naked eye that robots controlled by KeMotion move more smoothly than ones with conventional control. Thanks to Look Ahead Path Planning, jerky braking and accelerations Figure 5 shows the position, speed and acceleration pattern of a conventionally planned motion (red) compared to a sequence with Look Ahead Path Planning from KEBA (green). commonly found when several robots are used in a shared workspace are a thing of the past.

In short, Look Ahead Path Planning with KEBA's KeMotion robotic control system comes with significant gains in productivity and great savings potential. Throughput is increased, and maintenance and energy costs are effectively reduced.

Ultimately a principle familiar from driving lessons proves to be true of robotics: "If you always think ahead, you will reach your destination in less time, more safely and more economically."

There will be a live demonstration of the KeMotion system from October 28-31, 2012 at PACKEXPO Booth N-4773 in Chicago.

About KeMotion

KeMotion is the open robotic control platform from KEBA that enables you to build and optimize your own robot with off-the-shelf controls technology.  Support for standard robot kinematics, teach functionality, and 3D simulation are some of the building blocks available to get your own robot up and running quickly.  Optimized solutions for the packaging industry are included, with features such as palletizing and pick & place configuration tools.  In addition, PLC functionality is included on the same platform, making your robotic and handling systems more seamless and cost effective.

This unique approach makes it easy to achieve advanced functionality with your own robot, and to develop an entire packaging line solution using a common control platform.

About KEBA

KEBA designs and manufactures innovative, easy-to-use automation solutions for industrial, banking and service, and energy sectors.  The privately owned company has over 40 years of experience and is based in Linz, Austria, with subsidiary locations worldwide.

In its Industrial Automation business, KEBA offers complete optimized solutions for robotic and machine control, mobile HMI, and end-of-arm force control.

Contact:
Douglas Riffle
+1 (248) 526-0561

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