Design Methodology in the Development of Mechatronic Products -Part 1

Transcription

1 Design Methodology in the Development of Mechatronic Products -Part 1 Robert Bjärnemo Division of Machine Design at the Department of Design Sciences

2 Agenda On the Concept of Mechatronics Characteristics of an Intelligent Mechatronic System Engineering Design and Mechatronics On the Concept of Intelligent Systems On Product and Systems Architecture What is Product Architecture? Establishing the Product Architecture Handling Interface Problems

3 What is Mechatronics? BSDB p 12 According to Mechatronics and the design of intelligent machines and systems by Bradley, Seward, Dawson and Burge (BSDB) MECHATRONICS is described as: Mechatronics provides both a title and a focus for the design and development of a wide range of engineering systems, both products and processes,, in which the technologies of electronics, software engineering and information systems are integrated with mechanical engineering.

4 The Constitutive Elements of Mechatronics BSDB p 11 Information Technology & Software MECHANICAL ENGINEERING Mechanization Electro Mechanical Systems MECHATRONICS Electrical Technology Electronics

5 The General Structure and Concept of Mechatronics and Mechatronics Systems Systems BSDB p 12

6 The Major Characteristics of an Intelligent Mechatronic System System BSDB p 14 generally complex systems exhibiting high levels of integration; increased functionality with respect to conventional systems; transfer of function from the mechanical to the electronics and software domains; system assumes responsibility for process allowing operator to concentrate on procedures; distributed processing with devolved intelligence; multi-sensor environment; system operation generally transparent to user; multi-program environment with user selection.

7 An Example of a Mechatronic System A Camera Camera BSDB p 14 Automatic, auto focus reflex camera with interchangeable lenses - in which each of the major 'hard' elements of the system; body, lens and flash-gun, constitutes a mechatronic system in its own right. Determining the required combination of aperture and shutter speed and of maintaining focus becomes the responsibility of the camera. The user is therefore freed to concentrate on achieving the desired composition!

8 Mechatronic Relationships BSDB p 20

9 Engineering Design and Mechatronics Positioning Engineering Design BSDB p 23

10 Engineering Design and Mechatronics Development and Design Costs BSDB p 22 Development phase Percentage of total cost Incurred Committed Conceptual Design Embodiment Design Testing Process Planning Production The Cost of Design Change During Design 1 During Testing 10 During Process Planning 100 During Pilot Production 1000 During Final Production Relative Cost

11 On the Concept of Intelligent Systems What is Intelligence? BSDB p 40 intelligence, n. 1 a the intellect; the understanding. b (of a person or animal) quickness of understanding; wisdom. 2 a the collection of information, esp. of military or political value. b people employed in this. c information so collected. d archaic information in general; news. 3 an intelligent or rational being. intelligential adj. [Middle English via Old French from Latin intelligentia (as INTELLIGENT)]. Concise Oxford Dictionary, 9th edn, 1995

12 On the Concept of Intelligent Systems An Typical Intelligence Test Question BSDB p Which is the odd one out?

13 On the Concept of Intelligent Systems Aspects of Human and Machine Intelligence BSDB p 42

14 On the Concept of Intelligent Systems The Turing Test BSDB p 43 A human interrogator has two dumb terminals, one of which is connected to a computer and the other to a human operator as in the figure. The interrogator can send and receive messages via these terminals. If after any length of time the interrogator cannot tell which of their two terminals is connected to the computer and which to the human operator, then the computer may be said to be intelligent.

15 On the Concept of Intelligent Systems Types of Machine Intelligence BSDB p 43 Description Example Characteristics Single Function Drill Capable of only one operation Automatic Pick and place mechanism Carries out a single fixed sequence Programmable CNC machine tool Carries out a sequence of operations under programme control Adaptive Fly-by-wire aircraft Autonomously adapts to changing conditions using sensory feedback. Goal Seeking Self guided vehicle Adapts to changes in environment in relation to a defined goal Advanced Data Capable of strategic decision making Autonomous and planning

16 On Product and Systems Architecture BSDB p 52 Within electronic engineering and software engineering, as well as for products in general, the term architecture, or more specifically product architecture, is used to describe the organization and structure of a system or a product and the ways in which the various elements of the product/system interact. The choice of product/system architecture is therefore likely to be a critical factor in determining the way in which an intelligent machine or a product operates.

17 On Product and Systems Architecture BSDB p 52 Von Neumann architecture Named after the mathematician John von Neumann, this architecture describes the configuration of most common computer systems. Also referred to as a random access sequential machine, a von Neumann architecture assumes the existence of a central processor and read-write random access memory as in the figure. In operation, the processor sequentially executes instructions stored in memory using data stored elsewhere in memory.

18 On Product and Systems Architecture BSDB p 52 Parallel architecture Parallel architectures are based around a number of processors sharing access to common memory as in the figure. Execution of instructions is allocated to individual processors in turn according to loading, enabling significantly shorter processing times to be achieved.

19 On Product and Systems Architecture BSDB pp Distributed and embedded systems architectures In a distributed architecture, processing power is devolved to individual elements or components within the system, each of which essentially runs its own independent program based on local memory. Thus in the camera system, each of the elements; body, lens, flash gun and data back; contains all the processing capability required to enable it to operate as part of the overall system together with an appropriate interface to enable communication with the other elements of the system.

20 On Product and Systems Architecture BSDB pp Hierarchical architecture A hierarchical architecture is organized as a tree structure such as that shown in the figure, in which each member, with the exception of the topmost member and bottommost members of each branch, are both the parents to the members of the hierarchy in the layer below them and children of a member of the hierarchy in the layer above them. Thus at the top level of the hierarchy sits the complete system while the lowest level of each branch describes one of the individual elements or components that make up the complete system. Information flows up and down the layers in the hierarchy in a strictly ordered manner from parent to children and vice versa. System

21 On Product and Systems Architecture BSDB pp Network architectures Networks may take a variety of forms such as those shown in the left figure. Unlike a hierarchical configuration, all members of a network are essentially equal, though there may be some bias in order to assign priorities to certain nodes. Each node of the network can itself be based around a microprocessor or micro controller which provides local processing power and hence forms the basis of the distributed and embedded system that is at the heart of many mechatronic systems. Thus, the camera, below, can be redrawn as a bus architecture with the processor in the main body acting as system controller.

22 What is Product Architecture? In a product the physical elements are typically organized into several major physical building blocks or chunks or simply subsystems. A product architecture is the scheme by which the functional elements of the product are arranged into physical chunks and by which the chunks interact. The product architecture belongs to either of the two main groups: Integral architecture Modular architecture

23 Integral Product Architecture An integral product architecture exhibit one or more of the following properties: Functional elements of the product are implemented using more than one chunk. A single chunk implements many functional elements. The interactions between chunks are defined and may be incidental to the primary functions of the product.

24 Example Integral Product Architecture The BMW R1100RS exhibits function sharing and an integral architecture with the design of its transmission chunk.

25 Modular Product Architecture A modular product architecture has the following properties: Chunks implement one or a few functional elements in their entirety. The interactions between chunks are well defined and are generally fundamental to the primary functions of the product. In the completely modular product each functional element of the product is implemented by exactly one physical chunk and in which there are a few well-defined interactions between the chunks.

26 Types of Modularity Slot-Modular Architecture Each of the interfaces between chunks in a slot-modular architecture is of a different type from the others, so that the various chunks in the product cannot be interchanged. Bus-Modular Architecture In a bus-modular architecture, there is a common bus to which the other chunks connect via the same type of interface. Sectional-Modular Architecture In a sectional-modular architecture, all interfaces are of the same type, but there is no single element to which all of the other chunks attach.

27 Platform Product A platform product is built around a preexisting technological subsystem (a technological platform). Examples: Sony Walkman and the Hasselblad camera. Product built on technology platforms are much simpler to develop than if the technology was developed from scratch.

28 Example Platform Product Official GM Platform Definition Powertrain: engines, transmissions, shifts Chassis front & rear: suspensions, brakes Engine cradle and rear suspension frame Steering system: steering gear Exhaust system Fuel storage and handling system Heat,Ventilation & AC system Cooling system, intercoolers, condensers I/P structure, cross bar & knee protection Steering column, except steering wheel Underbody, front & rear structures Front & rear seat structures Moveable roof cassettes Charging & energy storage

29 Establishing the Product Architecture Step 1: Create a Schematic of the Product A schematic is a diagram representing the development team s understanding of the constituent elements of the product. Here a schematic of the DeskJet printer by HP. Note the presence of both functional elements (e.g. Store Output ) and physical elements (e.g. Print Cartridge ). For clarity not all connections among the elements are shown!

30 Establishing the Product Architecture Step 2: Cluster the Elements of the Schematic The challenge here is to assign each of the elements of the schematic to a chunk. In order to facilitate the clustering following factors are considered: Geometric integration and precision Function sharing Capabilities of vendors Similarity of design or production technology Location of chance Accommodating variety Enabling standardization Portability of interfaces

31 Establishing the Product Architecture Step 3: Create a Rough Geometric Layout Creating a geometric layout forces the the team to consider whether the geometric interfaces among the chunks are feasible and to work out the basic dimensional relationships among the chunks.

32 Establishing the Product Architecture Step 4: Identify the Fundamental and Incidental Interactions It is most likely that a different person or group will be assigned to design each chunk. Because the chunks interacts with one another in both planned and unintended ways,, these groups will have to coordinate their activities and exchange information between the chunks. An interaction graph is a convenient way to represent the incidental interactions.

33 Handling Interface Problems The method presented here is based on the concept of feature based transformations between the constituent subsystems. The following steps are to be carried out: 1. Identification of the overall system (incl. its in- and output vectors). 2. Identification of subsystems 3. Identification of type of interface 4. Development of physical interface-element element

34 Step 1: Identify the Overall System Type of system Identifier Version number Input status Output status INPUT OUTPUT Transfer function

35 Step 2: Identification of Subsystems An interface problems is at hand when the output form subsystem 1 doesn t match the input to subsystem 2!

36 Step 3, 4: Identifying Type of Interface and Develop Physical Interface-element element

37 Example - Flange

38 Example - Flange