|
Project 1:
Title: Reconfigurable Assembly
Systems
Increasing complexity of current products with
simultaneous higher performance requirements place exceedingly
high demands on modern MMPs (convertibility, scalability,
diagnosability) creating a critical need for
reusable/reconfigurable manufacturing systems. Our research
to this end focuses on the following:
-
Comparative analysis of current assembly systems with respect to
their reconfigurability
-
Development of partitioning method for assessment of system
reconfigurability based on the concept of task similarity and
“rework distance”
-
Development analytical tools for information mining in CAD/CAM
system to optimize reusability and/or required minimum
reconfigurability for part family
The aforementioned problems are investigated in the following
ways:
Task 1. Assembly system Partitioning and Similarity Measures ([TBS1])
Step 1: Assembly System Partitioning using Key Characteristics (KCs).
Objectives: - To partition product & assembly
system based on system discretization of (i) product into Key
Product Characteristics (KPCs) & (ii) process into Key Control
Characteristics (KCCs) to identify similarity-based part family
Step 2: Similarity Measure of Product Architecture: Common
Product Architecture.
Objective: To Identify common architecture for a
product family, and develop a common assembly system architecture
Step 3: Similarity Measure of Assembly Fixture Layouts: Common
Assembly System Architecture.
Objective: To develop a methodology which can
convert one production line to another with minimum rework
operation costs.
Task 2A. Fixture Workspace Synthesis for Reconfigurable
Assembly Systems([22])
Objective: Identify the best superposition of
fixture locating layouts for selected family of parts, by which
the corresponding locating points of the
family of parts will be contained within the Functional Workspace
Envelope of the reconfigurable tool
Step 1: Obtain preliminary fixture layout
configuration for the selected part family using procrustes
analysis approach (translations/rotations of fixture layout)
Step 2: Minimize the necessary fixture workspace
envelope ((Cm)Min(Max)) for the selected part family using fixture
layout Pairwise optimization required by Min(Max(Ci))
Description: Reconfigurability of
assembly systems is becoming critically important in the rapidly
changing market where a family of products needs to be produced
on a single production line. This paper presents an approach
that allocates the best superposition of locating layouts for a
family of parts to be produced on a single reconfigurable
fixture. The presented methodology is based on the procrustes
analysis integrated with a pairwise optimization of fixture
workspace configurations. A case study illustrates the proposed
approach.
Task 2A. Fixture Workspace Synthesis for Hybrid Assembly
Systems ([38])
Description: Rapid market changes and
diversification in customer preferences have led to the
development of mass customization. This has further increased
the importance of responsiveness and convertibility of
manufacturing systems. Currently, flexible and/or reconfigurable
assembly systems are one of the primary technological enablers
in improving manufacturing system convertibility and
responsiveness (how do you differentiate between responsiveness
vs. convertibility) for new product development. However, the
application of a single type of assembly system: dedicated,
flexible or reconfigurable, may not be the most effective
solution in today's requirements of product life management (PLM).
Thus, this paper proposes a methodology for design analysis of
hybrid assembly fixture, which aims at an optimum integration of
dedicated, flexible and reconfigurable fixtures in a single
assembly system. The proposed methodology applies fixture
workspace synthesis to optimize the fixturing layout for a given
part family, and identify appropriate fixture tooling elements
to construct a feasible hybrid assembly fixture. in doing so it
fulfills the dual requirements of system convertibility and cost
effectiveness. A few case studies are provided to illustrate the
procedure
of the proposed methodology.
Task 3. Visibility Analysis for
Reconfigurable Assembly Fixture Calibration ([S2])
Objective: Minimize the number of necessary
setups of measurement system (laser tracker) for assembly fixture
calibration, i.e., to identify the minimum number of positions,
from which measurement equipments are visible to all the
Measured Targets (MTs: fixture locators & clamps), without
being blocked by any obstacles.
Description: In a number of
manufacturing processes, tooling installation, calibration and
maintenance guarantee the precision of fixtures and play
important roles towards the overall quality of products.
Recently, a new type of measurement equipment called "laser
tracker" was developed and utilized for assembly fixture
calibration to shorten calibration time and improve the accuracy
of the currently used theodolite systems. Though calibration of
assembly fixture is critical for product quality, as such
calibration time creates significant burden for productivity of
multi-station assembly processes. In order to shorten
calibration lead-time, the number of necessary setups,
determined by visibility
analysis, needs to be minimized. This paper presents a screen
space transformation based visibility analysis that allows
minimizing the number of setups. The screen space transformation
is applied to transform the visibility problem from 3D to 2D
space thus, efficiently solving the visibility problem. A case
study illustrates the procedure and verifies the validity of the
proposed methodology. This methodology can be applied for not
only manufacturing process such as in-line fixture calibration
but also towards analysis and optimization of AGVs, robots
navigation system and building security.
Task 4. Rapid Deployment of Reconfigurable
Assembly Fixtures ([24])
Objective: Develop an analytical tool for rapid fixture
deployment which allows for simultaneous optimization of both (i)
reconfigurable fixture capability to produce a family of parts and
(ii) fixture visibility to minimize number of setups.
Description: Due to rapid changes in
recent market demands, shortened production ramp-up/launch and
model changeover of new products with simultaneous manufacturing
of family of products on a single production line is becoming
inevitable. This requires systematic methods for rapid design
and analysis of reconfigurable fixture workspace synthesis and
visibility. This paper presents an integrated approach for rapid
reconfigurable fixture deployment which is based on (1) the
procrustes analysis integrated with a pairwise optimization for
fixture workspace configurations synthesis; and (2) screen space
transformation-based visibility analysis for rapid fixture
calibration. A case study and simulations illustrate the
proposed approach.
Project 2:
Title: Quality-driven Sequence
Planning for Compliant Structure Assemblies
Description:
Assembly sequence planning is an integral part of a new product
and process development. However, currently there are very few
available approaches to evaluate the impact of assembly
sequences on product quality. This paper develops a methodology
for quality-driven sequence planning (Q/SP) with consideration
to product dimensional quality based on the following three
steps: (1) Sequence generation for predetermined line
configurations using k-piece mixed-graph representation of
assembly; (2) Dimensional quality model of variation propagation
for assembly processes with compliant parts; and (3) Evaluation
of sequences based on the multivariate process capability index.
The methodology is illustrated using an industrial case study.
|
