1. The Representation Challenge CPN’s then seem to provide the necessary structure to represent AT systems For this to be successful, the representation of the components of AT systems needs to be sufficiently detailed to reflect the many facets of Person, Environment and Activity which make up these systems

2. Representation and Tokens At the heart of CPN Representation are the markings which consist of sets of tokens at the various places. These sets of tokens define the state of the domain before and after the transitions. Guards are tested against the sets of tokens and outcomes describe the effects of activity on the tokens So tokens are at the centre of this representation scheme.

3. To establish what is required Consider Our AT System which consists of - A Person In Some Environment Performing Some Activity (possibly with the help of ) Some AT We need token definitions which represent which represent the above

4. CPN tokens CPN Tokens have rich representation capability and are suited to representing the Person - Environment Activity and AT tokens required in modelling AT systems Best way of representing these elements of activity is using CPN record token structure. Basically a sequence of labelled types with values. Can use CPN Union tokens to join up subsets of various component tokens

5. In subsequent sections The structure of these AT system elements are discussed. These elements namely PERSON, ACTIVITY,ENVIRONMENT and AT are summarised in the following diagram

6. PERSON -ENVIRONMENT –ACTIVITY- AT

7. Lift Up Kettle Carry Kettle over to sink CONSIDER For Example ACTS PERSON Environment AT Considered Later

8. From the Preceding There is a Person The Physical Environment is a Kitchen (Note there are other Environmental Components) The Activities Include: Lifting a Kettle and Transporting it to the Sink

9. Representing these All Components of AT systems must be represented in any model In Other Words

10. Need to Represent The person who carries out the task The environment in which the task is carried out. Objects of the Domain (Including AT Artefacts). These are often considered Environmental Concepts Finally The Activities.

11. Representing the Person

12. The Agent The person who performs the task is known as the Agent Need to represent the Agent Attributes Agent Capabilities

13. Agent Attributes There are many attributes to consider These include Personal Factors Age, Gender, Height Profession etc Body Structures Absence or Lack of any significant body structures such as hand leg Anthropometric Data such as reach, height, body dimensions

14. Agent Capabilities There are many: Body functions such as mobility, cognitive Activity and Participation data Psycho Social MPT Data For example

15. If a person wishes to perform this task 1: They need to want to do this 2: They need to be able to locate the kettle 3: They need to be able to move to the kettle 4: They need to be able to grip the kettle handle 5: They need to be able to lift an empty kettle

16. In other words There are many attributes of the person being tested against the requirements of the task. These include Agent capacities e.g the ability to lift etc They also include assumptions about the availability of body structures such as hands and eyes The following are at least all of the features of a person which may be considered.

17. Person Personal Attributes Body Structures Anthropometric Data Body Functions Activities and Participation Psycho- Social Other

18. Representing the Environment

19. Two Broad categories Environmental Factors Such as – Physical Environment – Attitudes – Policy and Legislation – Relationship and Associations Objects in the Environment including Assistive Objects

20. Representing Environmental Features There are two categories, Physical Objects that make up the environment and other factors that fall into environmental classification These latter categories based on those from the ICF include:

21. Attitudes Services Policy and Legislation Physical Environment Relationship and Associations

22. Physical Environment These factors include attributes of the environment such as Lighting Terrain Habitat Whether indoors or outdoors Objects are considered separately

23. Attitudes Attitudinal factors have been shown to impact on AT use These include Attitudes of Self Attitudes of Peers Cultural Attitudes Religious Attitudes

24. Services Policy And Legislation Legislative and Policy mandates have a huge bearing on successful AT use. Legal Aspects impacting on AT use include: Service Provider Policies and Mandates Local and National Legislation AT Service Provision Policies

25. Relationships and Associations Family Friends and Acquaintances Strangers People in Authority Personal Assistants Health and Other Professionals

26. Representing Objects

27. The Key Environmental Representation The objects including Assistive Technology that populate the activity domain are central to any representation scheme of AT systems

28. Representing Objects Need to represent Position Need to represent static and dynamic attributes Need to represent components. Need to represent smart knowledge - (that is how the object is interacted by an agent)

29. Object Interaction Interacting with the objects of a task is an important ability in activity participation Task objects place important demands on the person carrying out the task These are called Capability or Capacity Demands

30. Representing Object Interactions Object interactions are described by Interaction Tokens which are associated with each Object Each Object may have more than one interaction token linked to it. This reflects that each object may be interacted with in different ways This knowledge is called Smart Knowledge

31. Predicates In addition to the above we need to be able to represent facts about the domain. These will be called Predicates and describe associations and relationships such as one object is next to another. Some are explicitly declared and some are calculated from object attributes such as position vectors

32. Examples of Dynamically Calculated Predicates Spatial functions – Beside, Near, On top of etc These are example of Fluents (Facts and Statements about the world that Change across states)

33. Other Issues Represent the action Do all this using CPN token representation.

34. Representing ACTIVITIES

35. Representing Actions As stated previously Three components of Action are identified – Intended Action which give Parameters of the activity such as Duration Location etc – Guards – Outcomes

36. Intended Actions Badler and others explicitly describe the action that is about to be performed (Uninitiated Parameterized Action Representations- uPARs) These uPars describe details of the Action such as Duration, Location, Source and Desination and much more The biggest advantage of this is that it allows us to distinguish between different instances of the same class of activity

37. For example The person making tea will have to lift a number of different objects including the kettle, teapot, tea caddy sugar bowl and so on. All of these instances of the activity “to Lift” have different characteristics and place different capacity demands on the person performing them. For example lifting a full kettle requires greater strength and a different grip than lifting a sugar bowl.

38. Case Structure A common way of capturing this kind of information is using case structure. For example the cases of “John Lifted the Kettle” would include – Agent (John) – Act (Lift) – Object (Kettle) – Location (Kitchen) – Time (3pm)

39. From this knowledge We can provide features to be used in the guard on the transition We can describe agent capacities and Performance specific to this intended ACT As we will see later we can use this to integrate the ICF into this representation Many computer Systems such as planning systems use just Pre (Guards) and Post (Outcomes) Conditions to represent Activity

40. Guards The preconditions on an activity are represented in CPN’s by the transition Guards These demands are the requirements that must be met by the agent and the environment and the pre activity state in general before execution of the activity Consider for example the following

41. Capacity Demands (Capability Demands Clarkson)

42. Looking at the above milk bottle designs: Each bottle design demands that the user has a capacity to perform a vertical lift by gripping the handle with a closed fist grasp. We see that the bottles on the left will allow a greater range of hand sizes get a proper grip on the handle for lifting since it gives greater clearance dimension between handle and jug

43. In other words the structure of each bottle implies the user must have particular hand dimensions in order to manipulate the bottle Thus each bottle places different demands on the user attributes. If these demands are not met then the bottle cannot be used. This conflict is the essence of how capacity demands define the guards of our petri nets

44. Guard Demands There are many such demands There are Agent Capacity ( Capability ) Demands These include Object Capability Demands - Can the agent use an object involved in the activity. There are environmental demands For example is there enough space to carry out the task There are even Activity demands- Can the agent do that Activity for that long?

45. Demands of the Transition Guard These must be measured against the personal capacities of the agent and the attributes of the environment This is summarised in the following

46. Capacity Demands Action and Objects Agent Capacities, En vironmental Factors, State Attributes

47. More formally

48. Person Capacity Tokens Environment Attribute Tokens Action Capacity Demands Object Capacity Demands Environmental Demands Incoming Tokens representing Person and State Transition Guard representing Barriers ( in terms of Capacity Demands) State Action Tokens

49. Guard Construction Guards on a Transition then are constructed from the demands placed on the agent and environment by the activity and the objects involved in it. This is summarised by the following

50. Transition (Labelled Description) Guard Capability Demands PersonEnvironment Outcomes Action/Activity---Objects

51. Outcomes These are the effects or outcomes of an activity. More formally they are whatever changes to the state occur as a result of the activity or event In the next slide examples of possible state changes will be presented

52. Example outcomes Objects get moved so their position changes This in turn will change dynamically calculated predicated values. For example some object is no longer beside another object. It could be an environmental change such as an obstacle is removed from a path It could be a change to a person’s capacities. They get tired after performing the task. It might be change in the persons mood. They learn a new skill and get a job- so they are happy

53. Outcomes and AT All the AT interventions previously mentioned result in state change Some AT interventions restore or establish capacity for example an augmentative speech device. Some change the environment and the capacity demands it places - for example a ramp is easier to traverse than steps Some interventions change the capacity demands of the Activity

54. Capacity Demands And Assistive Technology Action and objects place capacity demands on people and environment. For example using a standard kettle involves a capacity demand of being able to perform a vertical lift of up to 1 kg(which is the weight of the kettle when full with water), one handed using a closed fist grip. Assistive Technology changes the relation between personal and environmental capacities and the capacity demands of the action being executed. This relationship is represented by the guard of the CPN This is shown in the following example

55. Using a kettle tipper Changes Capacity Demands

56. In the above example The pouring capacity demand involved in using a standard kettle is substantial. Using a tipper, reduces this capacity demand. A person may not have capacity to meet the pouring capacity demand of a standard kettle, but will have enough using a tipper. The guard which represents capacity demand versus personal capacity will fail on the standard kettle transition but will be satisfied using the tipper transition

57. In Summary Outcomes can change any part of any token of the input state. Based on what has gone before we have at least the following tokens at each input place

58. Person Tokens Environment Tokens Intended Action Tokens Object Tokens Predicate Tokens Interaction Tokens Contextualised Tokens

59. Outcomes and Tokens Outcomes can change any part of any token of the input state. In other words all of the above tokens can be changed after a transition. This is shown in the following:

60. Places and Transitions Person Tokens Environment Tokens Intended Action Tokens Object Tokens Predicate Tokens Interaction Tokens Contextualised Tokens Person Tokens Environment Tokens Intended Action Tokens Object Tokens Predicate Tokens Interaction Tokens Contextualised Tokens Guards Transition Outcomes Input Set

61. Changes that can take place If it’s a token field with a numeric value it can increase or decrease that value It can replace non-numeric fields with appropriate substitute values This is summarised in the following diagram

62. Outcomes Transition Outcomes Specified Token Changes + Enhancements - Inhibitors