Citation: Mohammed, S.K.; Arbo,
M.H.; Tingelstad, L. Constraint
Definition for Gripper Selection and
Grasp Planning for Robotic Assembly
Using Product Manufacturing
Information from STEP AP242Ed2
Files. Machines 2022, 10, 1230.
https://doi.org/10.3390/
machines10121230
Academic Editors: Yuansong Qiao
and Seamus Gordon
Received: 12 September 2022
Accepted: 13 December 2022
Published: 16 December 2022
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Article
Constraint Definition for Gripper Selection and Grasp Planning
for Robotic Assembly Using Product Manufacturing
Information from STEP AP242Ed2 Files
Shafi Khurieshi Mohammed
1,
*, Mathias Hauan Arbo
2
and Lars Tingelstad
1
1
Department of Mechanical and Industrial Engineering, Norwegian University of Science and
Technology (NTNU), 7034 Trondheim, Norway
2
Research Scientist, SINTEF Manufacturing AS, 7031 Trondheim, Norway
* Correspondence: shafi.k.mohammed@ntnu.no;
Abstract:
This article uses the Product Manufacturing Information (PMI) from STEP AP242 neutral
files for gripper selection and grasp planning in a robotic assembly operation. The PMI, along with
the part geometry and dimensions, are used in identifying various handling features of the parts and
selecting an appropriate gripper. The required PMI, like material, volume, surface finish, threading
and coating information, are added to the STEP AP242 files. The PMI is semantically included in the
STEP files following the Model Based Definition (MBD) methodology. Two methods are described
to add the PMI to the STEP files, one using a custom string and another using the standard entities
defined in ISO 10303 AP242: 2020 standard. The entire process is demonstrated in a use case.
Keywords:
robot; assembly; STEP AP242; ISO 10303; STEP; Model Based Definition (MBD); Product
Manufacturing Information (PMI); constraint based robot programming
1. Introduction
Industrial grippers are crucial in many types of equipment like NC and special purpose
machines, fixed automation, workpiece turrets and industrial manipulators [
1
,
2
]. The
problem of robotic grippers is not new [
3
], but with the increasing adoption of robotic
applications under Industry 4.0 [
4
], their importance is increased as they are the essential
tool in many industrial operations like material handling [
2
]. Grippers are an essential
component for the success of robotic assembly operation [
5
] as they affect both the cost
and time of automation [
6
]. Hence, selecting an appropriate gripper and proper grasp
planning will increase the successful completion of assembly operations with less time and
lower cost.
The gripper selection and grasp planning is critical in the case of small and medium
enterprises (SMEs) as they handle significant product variations and lower production
volumes compared to mass production. As the product design changes, the SME needs to
make the gripper selection and grasp planning for each change, which results in increased
time and cost required for robotic assembly. The gripper selection and grasp planning
process can be improved using product information. Product information is made available
for all the stakeholders and downstream operations by adopting the Digital Thread (DT)
methodologies as per Industry 4.0.
Mohammed et al. [
7
] used a method to add welding information semantically to the
STEP files. This paper extends that method to include relevant PMI to the STEP AP242
Ed2 files and reuse it to identify the constraints for grasp planning. We also identify the
information required for gripper selection and grasp planning from the existing literature
and how this information can be included in the STEP AP242 files as per the latest industry
standards. A method to extract the relevant information from the STEP files and iden-
tify the constraints for gripper selection and grasp planning is proposed. This process is
demonstrated using a motor assembly use case.
Machines 2022, 10, 1230. https://doi.org/10.3390/machines10121230 https://www.mdpi.com/journal/machines
