Global Perspective: Robotic suction cup analysis
Deformation analysis optimized use of suction cups under combined load for robotic product handling with vacuum gripping heads.
Loading of suction cups during the handling or motion (chassis of service robots) cycle is highly variable. Specific cases of suction cup load (loading in the radial and axial direction as well as the torque and heeling/tilting moment loading) can be monitored and analyzed. Specifically defined boundary conditions and a material model of contacting bodies can improve deformation behavior and robotic efficiency. The simulation finds admissible margin for a variable (contact stability, for example) of the suction cup deformation depending on the margin allowed for safety.
Set a safe margin
Robot handling of certain products typically uses vacuum gripping heads. During application setup, it is necessary to specify the suction cup safety level so that the gripping or holding system satisfies stability requirements, accounting for possible changes in friction on the boundaries of contact surfaces.
Inaccurate positioning can create undesirable loading of the sheet being gripped and excessive loading of the robot wrist and vacuum gripping elements.
It’s important to analyze deformation behavior of suction cups and basic loading types in the computer model for safe gripping.
Deformation analysis of suction cup
Suction cup load varies by the combination radial FRAD and axial FAX forces depending on gripping plane orientation. If the gripping system is insufficiently sized, especially if the safety coefficient is chosen incorrectly, these changes can result in a loss of contact stability and collapse when the suction cup is pulled off or the contact profile in the gripping plane shifts.
Boundary conditions describe the character of frictional conditions based on laboratory test results. Friction coefficient values depend substantially on the contact material surface (wet, dry, wet with oil, without oil).
The computer model was optimized for a variable active surface of the suction cup which, depending on the loading profile, is the effective diameter of the suction cup. Contact area corresponds to the loading level (contact quality) during each step of the calculation. Including this effect improved computer model accuracy for suction cup behavior during external loading.
Computer simulation results
Simulation results compared to outputs of laboratory experiments confirmed substantial agreement.
Multi-element gripping heads integrated with the service robot chassis can eliminate effects of tilting.
The computer simulation shows that particular suction cups loaded in the combined way can be deformed substantially, leading to considerable contact instability with adverse influences on the safety of object gripping and holding. Using more suction cups allows greater axial-force loading while tilting.
A computer simulation can help with setup and improve operation of service robotics with mobile chassis, especially those used on vertical walls (such as autonomous washing and inspection activities at inaccessible places like high-rise buildings with glass casing/facade). This work resulted from Research Plan No. MSM 4674788501, funded by the Ministry of Education, Youth, and Sports of the Czech Republic.
At a glance
- computer simulation
- suction cup
- combined load
- safety coefficient
Marcel Horák and František Novotný are with Technical University of Liberec and contribute to Control Engineering Poland and Control Engineering Czech Republic. Reach them at marcel.horak(at)tul.cz, frantisek.novotny(at)tul.cz
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Automation Conferences in Poland
In Poland, conferences bridge science and industry. Polish researchers need the practical testing of their ideas within real processes to uncover the pros and cons of the proposed solution. Automation companies look forward to cooperation with universities on research projects. Control Engineering Poland served as a media sponsor for the following conferences:
- Methods and Models in Automation and Robotics
- Conference on Active Noise and Vibration Control Methods
- International Carpathian Control Conference
- School of Modal Analysis
- Protech, organized by Control Engineering Poland publisher.
These conferences enable the possibility to present the highest quality works from the area of control engineering as well as mechanical engineering and mechatronics. This is among the best papers presented.
- Krzysztof Pietrusewicz, PhD, West Pomeranian University of Technology, Szczecin, Poland; Control Engineering Poland