1. Introduction

The MPMS is the collection of subsystems responsible to orchestrate the tasks of agents in the manufacturing processes. Orchestration is dependent on the design of the processes and agents. The MPMS includes the functionality to design processes and describe agents, and execute the processes by deciding on the next activities to be executed and assigning activities to agents. The figure below shows the process management functionality, embodied by the MPMS, as a function of horizontal and vertical integration. Horizontal integration refers to the inter-operability between the manufacturing processes and other management or support processes in the enterprise. Vertical integration refers to the link between the process management and resources located on the factory floor.


conceptual illustration of the MPMS in relation to the work cells

Conceptual illustration of the MPMS in relation to the work cells

  1. System delineation

a. Context

A manufacturing process consists of activities, events, gateways and connectors. Activities may be sub-processes or tasks. A single process may contain multiple tasks, located and performed in multiple work cells. A task is assigned to and performed by a team of one or more agents. This team may be a virtual team that only exists for the duration of the task execution. A single task is entirely contained within a single work cell, for the duration of the task. For this reason, task is considered the smallest unit of work that appears in the global layer. The MPMS enables the design of manufacturing processes and automatically supports the execution by coordinating which task should be executed by which agent.

b. Scope

The MPMS functionality can be placed in the global layer of the HORSE logical architecture. It consists of three system modules and a single data store within the larger HORSE System (see the figure below).

HORSE logical architecture with the MPMS modules highlighted

The HORSE logical architecture with the MPMS modules highlighted

  1. Requirements and functions

The MPMS covers several of the HORSE requirements.

  1. System Functions

Three process functions (PF) are associated to manufacturing process design and execution, each with at least one sub-function.

PF-01 - Horizontal Business Process Management

Allows the user to model, plan, configure, and support the execution the manufacturing process using a view that integrates the overall (horizontal) end-to-end process and the (vertical) sub-processes of the various work cells in the manufacturing system. Therefore, based on the desired output and performance, the system:

  • coordinates the routings of orders through the manufacturing system (i.e. it decides which tasks should be executed when and in which order for the production of a product)
  • plans and assigns the resources (e.g. human and robotic actors) to execute the various tasks and provides work instructions (such as assembly or executions scripts) through the task instructions function,
  • handles exceptions in the overall process execution that occur due to e.g. failures, unsafe situations, and unavailability, that cannot be handled by the work cell autonomously (cf. that cannot be dealt with through the situation awareness function). Its exception handling strategies consist of for instance halting (parts of) the overall process through the actor control function, and re-assigning resources to tasks through the resource management function.

The sub functions identified in this main function are: manufacturing process management and monitoring (SF-11), and structured exception handling (SF-12).

PF-02 - Resource management

The system interprets the manufacturing process configuration to determine the process resources necessary to execute the process. The system takes decision based on the most suitable resource e.g. capabilities (cf. competency matrix for a worker, or technical specifications of a robotic actor), and availability. It therefore, monitors the current and queued assignments and tasks of process resources, including humans, robots, containers, vehicles and other materials. Data obtained from this monitoring function will enable the system to determine whether the necessary resources for a specific production unit are available. In case of safety breaches, material unavailability, actor unavailability, failures or delays in previous steps, this module (through a request the manufacturing process management function) dynamically (re)allocate new resources and reassign tasks as necessary.

Only one sub function is distinguished: task allocation based on resource characteristics (SF-13).

PF-03 - Actor control

The system processes the manufacturing configuration models, manage the overall production process, allocate the appropriate resource to tasks, and handle process level exceptions by amongst other reallocating resources. To this end the actor control function allows interaction with the various type of actors. It enables the communication of work lists to the designated actors, and controls the execution progress (e.g. by halting and resuming the task execution of an actor).

Only one sub function is distinguished here: monitoring and control of work progress of all actors in the manufacturing process (SF-14).

  1. Functional requirements

The table below gives the subset of functional requirements established in deliverable D2.1 which are allocated to the MPMS.

Functional requirements related to the MPMS

System function

Code

Description

SF-4

FRQ-10

The HORSE System shall be able to monitor for every Robotic Actor:

a) its capabilities, including at least a.1) maximum load, and a.2) availability,

b) its performance, including at least b.1) task actual completion time, b.2) task estimated completion time, b.3) task successful execution estimation

SF-11

FRQ-22

The HORSE system shall be able to identify alternative manufacturing system configurations, based on input information.

FRQ-23

The HORSE System shall be able to monitor:

a) resources availability

b) performance, including at least b.1) process actual completion time, b.2) process estimated completion time

c) process current state

FRQ-24

The HORSE System shall be able to present information to the Operator including at least a) condition, b) state, and c) alerts, for each Robotic Actor and Production human actor.

FRQ-25

The HORSE system shall be able to visually present production schedule alternatives based on input data and Operator selections.

FRQ-26

The Robotic Actor should be able to support mobility concerning Logistics, when interfacing with the ERP system (i.e. autonomic bringing of the products depending on the received order).

SF-12

FRQ-27

The HORSE System may be able to alert the Operator while it is uncertain if one of the Robotic Actors can successfully complete a task within a minimum possibility of failure.

FRQ-28

During exception handling, the HORSE system shall be able to initiate the out-of-normal action process.

FRQ-29

The HORSE System shall be able to re-allocate actors, in response to external events, including at least a) safety alerts and b) sensor failures.

FRQ-30

The HORSE system shall be able to re-allocate tasks to actors, based on cumulative work load and manufacturing system status.

SF-13

FRQ-31

The HORSE system shall be able to determine the availability of actors needed for a specific manufacturing system configuration.

FRQ-32

The HORSE System shall be able to dynamically re-allocate actors to tasks based on task safety risk and ergonomic information.

FRQ-33

The HORSE System shall be able to select and allocate appropriate actors to tasks based on their specific capabilities.

SF-14

FRQ-34

During exception handling, the HORSE System shall be able to halt or resume the task execution of an actor, based on manufacturing system status.

FRQ-35

The HORSE System shall be able to send a list of tasks to be performed by each actor in the production line, for a specific production order.

FRQ-36

The HORSE System shall be able to accept notifications from actors in the production line regarding a change of manufacturing system status, including at least a) actor availability and b) safety risks.

FRQ-37

The HORSE System shall be able to manage operational mode and the task state, for all actors.

  1. System description

On the HORSE Design Global level the functionality is roughly divided between the process design and agent design sub-systems. These sub-systems can be used independently as needed for the task at hand.

  • The Process Design module contains the functionality to (re-)design manufacturing processes. Results of design activities are stored in the Process/Agent Definitions data store. In case of redesign, the input is retrieved from this database. It enables the visual modelling of a manufacturing process, comprising of tasks, events, gateways and connectors, and links the tasks to the task definitions and agent definitions.
  • The Agent Design module contains the functionality to design manufacturing agents, i.e., describe their relevant characteristics including their competences, authorisations and performance indicators.

A more detailed design of the functionalities of the MPMS Global Design modules can be found in the figure below.

Modules of the HORSE Global Design

Modules of the HORSE Global Design

The product definitions data store is contained and populated in external information systems, typically PLM or computer-aided design software. Task / step and cell data is populated in the local layer of the HORSE System.

The HORSE Exec Global sub-system contains the modules involved in execution of manufacturing processes. The figure below shows an elaboration of the MPMS Global Execution modules.

These modules provide the functions used to enact a sequence of tasks, assign agents to those tasks and provide the agents with necessary information. Exception handling and performance tracking modules are also included. Finally, the Production Execution Monitoring module supports real-time monitoring of manufacturing execution in terms of processes, orders, and agents (human and automated).

MPMS Global Execution modules

MPMS Global Execution modules

Together the MPMS modules in the Design global and Execution global support the automated orchestration of the manufacturing process while ensuring horizontal integration of the process activities and vertical control of all agents in the process.

The MPMS modules were realized as an extension on top of Camunda BPM, an open-source workflow management platform. Extensions include modeling patterns for manufacturing processes, vertical integration with agents, coupling to the specific HORSE middleware, dynamic agent allocation based on capabilities, etc.

As a final remark, it is prudent to state functions which are explicitly excluded from the system. The HORSE System does not include detailed planning and scheduling technology. Such technology is widely available and advanced. Instead, the MPMS aims for run-time control which orchestrates all agents in an efficient manner. Planning optimisation and detailed scheduling are assumed to be done and available as input to the HORSE System.

  1. Demonstration scenarios

The HORSE system was used in all pilot scenarios of the HORSE project.

TRI case

The TRI case is the most elaborate for the MPMS, with the most number of developments demonstrated. The table below shows the developments and functionalities that are demonstrated at the TRI case.

Summary of demonstrations at TRI pilot case

Demonstration of development

Combination of manufacturing process building blocks to create practical process model

The use of notation extensions to improve model understandability

The use of process analysis extensions to define process risks

Definition of task requirements to enable dynamic allocation

Definition of agent abilities to enable dynamic allocation

Enactment of process and assignment of tasks to agents

Dynamic allocation of agents based on task requirements and agent attributes

BOS case

The BOS pilot serves as an ideal demonstrator of the flexibility of the MPMS, by showing how a complicated case can be modelled and executed. The table below shows the MPMS developments and functionalities demonstrated as part of the BOS case.

Summary of demonstrations at BOS pilot case

Demonstration of development

Combination of manufacturing process building blocks to create practical process model

Use of events are notifications between HORSE System modules

Enactment of process and assignment of tasks to agents

OPSA case

The OPSA case is mostly focused on the exception handling development. However, process modelling and enactment is still required for the case. The table below shows the developments and functionalities that are demonstrated at the OPSA case.

Summary of demonstrations at OPSA pilot case

Demonstration of development

Combination of manufacturing process building blocks to create practical process model

Definition of events expected in the process

Enactment of process and assignment of tasks to agents

Structured exception handling based on event types