Product Packaging and Palletizing
Using a Rhino XR-4 Robot
And a Specially Designed Platform
by Margaret Frericks
Advisor:
Eftychios Christoforou
ESE 499
Systems Design Project
Spring 2006
Special thanks to Eftychios Christoforou, Sie Deen Lau, Heinz Schaettler
for their help during this project.
ABSTRACT
As part of this project, the operating condition of the two Rhino XR-4 robots of the ESE Department was examined. It was found that they are in good working condition, and their programming was learned. Next, two important robotic applications were investigated: packaging and palletizing. For this purpose, a special platform was designed, built, integrated with the robotic system, and tested experimentally. Lastly, a report and webpage was completed that includes how to the use the robot to package or palletize. The report and webpage can be used as a resource for future students and/or professors using the Rhino robots.
PROBLEM: Utilize the Rhino XR-4 Robot
The motivation for this project was to examine two important robotic applications, packaging and palletizing, using the Rhino XR-4 robots of the ESE Department. The Rhino XR-4 Robot is shown in Figure 1 below. The robot is controlled through the Rhino Mark IV Controller (Figure 2) by either the teach pendant (Figure 3) or by the RoboTalk software installed on a laptop.
Figure 1: Rhino XR-4 Robot Figure 2: Rhino Mark IV Controller Figure 3: Teach Pendant
The Rhino XR-4 Robot is a six degree of freedom robot. It is similar to a human upper body and arm with the ability to rotate at the waist, bend at the shoulder, bend at the elbow, bend at the wrist, rotate at the wrist, and grip. Programmable robots such as this are often used to perform tasks humans can not do for some reason, such as the task is hazardous, the task is too repetitive for a human to perform, or the task requires more precision than a human can provide. One area in industry where robots like this are used is to package or palletize products for shipping.
For this project, I wrote four computer programs in RoboTalk, a programming language provided with the Mark IV Controller, to perform packaging and palletizing tasks. I designed and built a platform and constructed objects to be used in the tasks. The platform includes a sensor that is triggered when the pallet is fully loaded, i.e. a weight limit is reached. This sensor was integrated into the robot’s controller and computer program by using an auxiliary input port on the Mark IV Controller.
RESULTS: Four RoboTalk Programs
Palletizing Wooden Cubes
The first program (BOXSTACK.rt) picks up four wooden blocks and places them onto the platform. The blocks are too light to use the weight sensor so the program simply stops after moving four blocks. This simulates palletizing because the blocks are arranged in two different orientations as would be used to closely stack products with various dimensions. The gripper on this robot limits the spacing of the blocks so that they are not in an optimized arrangement unlike the robots that would be used in an industrial setting. The steps are listed, and the video below shows this program.
Steps in BOXSTACK.rt
1. User places platform and blocks in correct positions and runs the program.
2. Robot picks up first block at far position.
3. Place first block at near position on platform.
4-5. Repeat steps 2 and 3 with second block.
6. Pick up third block.
7. Place third block at 90 degree orientation to first two.
8-9. Repeat steps 6 and 7 with fourth block.
10. Robot moves to home position at completion of the program.
Click Here for Video of BOXSTACK
Palletizing Batteries with Weight Sensing
The second program (PALLET.rt) palletized batteries onto the platform. Since the batteries were heavier than the wooden blocks, the weight sensor was used to indicate to the robot to stop placing batteries on the platform once a weight limit was reached. This weight limit was determined by the height of the sensor under the platform. The sensor was linked into the Mark IV Controller as an external input that can be used to indicate different steps in the RoboTalk code. The steps are listed, and the video below shows this program.
Steps in PALLET.rt
1. User places platform and batteries in holder in correct positions and runs the program.
2. Robot picks up first battery.
3. Reorients battery to prepare for placement.
4. Place battery on platform.
5. Sensor has not been triggered so will continue to place batteries on platform.
Repeat steps 2-5 with next two batteries in row.
6. First row of three batteries on platform.
7. Robot picks up fourth battery from next column.
8. Place battery on platform.
9. Pick up fifth battery.
10. Place battery on platform.
11. Weight sensor is triggered.
12. Light on Input 1 on Mark IV Controller indicates that the sensor has been triggered,
and the program ends with five batteries on the platform and one battery left in holder.
Click Here for Video of PALLET
Palletizing Batteries with Weight Sensing for Removal and Replacement
The third program (PALLET REMOVAL.rt) is very similar to the second program except instead of ending the program when the weight limit is reached, the program waits to see if a battery will be removed and will then replace the battery with another from the holder. The sensor is higher so that the weight limit is first reached with two batteries on the platform. The steps are listed, and the video below shows this program.
Steps in PALLET REMOVAL.rt
1. Place first two batteries. Weight limit is reached. Remove a battery so program will continue.
2. Robot retrieves and places third battery. Weight limit is reached so battery is removed.
3. Robot retrieves and places fourth battery.
4. Remove fourth battery so program continues.
5. Robot retrieves and places fifth battery. Remove a battery so program will continue.
6. Last battery is placed so program is complete.
Click Here for Video of PALLET REMOVAL
Sorting Cubes for Packaging
The last program (SORT.rt) sorted eight cubes of two different sizes into boxes as could be used to sort products for packaging. The gripper sensed the distance that it closed when picking up the block and that output is used to select which box to place the block into. The blocks could be placed in any order, and they would be correctly sorted by their size. The steps are listed, and the video below shows this program.
Steps in SORT.rt
1. User places blocks and boxes in correct positions and runs program. Blocks may be in any order.
2. Pick up first block and sense its width.
3. Places block in right box.
4. Pick up second block and sense its width.
5. Place block in left box.
At finish, the robot has sorted all eight blocks into the two boxes and program ends.
CONCLUSIONS
The objective of this project was to investigate uses of the two Rhino XR-4 Robots in the ESE lab. The robots are fully operational and can be programmed for many uses using the Teach Pendant and the RoboTalk software installed on a computer. The user should make sure the computer that is being used has both a serial port, for the Mark IV Communications Cable, and a parallel port, for the HASP Controller, since these are becoming obsolete ports. Although the RoboTalk programming language has limitations compared to full programming languages, such as C++, it is a good place to learn how to control the robot using a simple command set.
The objectives of this project were achieved through writing four programs for the robot to simulate packaging and palletizing of products. A platform with sensor was integrated into the auxiliary inputs on the Mark IV Controller to sense if a weight limit on the platform was reached. Using this experimental setup, important applications for industrial robots were investigated: packaging, sorting, and palletizing. In creating these programs, I learned that the robot may not repeat the same movements exactly run-to-run so one must have patience when troubleshooting a program. Overall, learning to use the Rhino XR-4 Robot is a good introduction to the programming and use of robots in industrial applications.