## 4 Model Building: FCM--Function-Capability Matching  
### FCM: Function-Capability Matching Theory  
#### 4.1.1 Methodology  
Starting from the primary interaction link of information reception, we find out the possible difficulties of elderly users in information reception and use the ability-needs matching method to research this, thus proposing the FCM (function-capability match) household product function-user life ability matching method. (1) Target layer establishment: The target layer belongs to the designer's idealised category. (2) Transformation of the implementation layer: The suitability of user needs and product functions is observed in the actual product use. The actual execution ability of the elderly user and the product's function is docked, and the bridge between the demand ability (the actual ability of the user) and the actual ability (the additional function of the product) is completed in both directions.  
The specific principle of the FCM home product function-user life ability matching method is that the user's interaction process experience can fluctuate within the ability matching range and the ability margin. The product's primary functions are added to match the user's ability to meet different users' needs for fresh and applicable products (as shown in Figure 6). The designer can then flexibly match the corresponding area with different target users' and producers' needs, avoiding the range of insufficient ability matching and, thus, achieving a balanced and unified paradigm value of function-ability. When people interact with the product, the actual ability of the user is no longer based on the hierarchy but on individual differences. The data are collected and aggregated to give feedback to the designer, which is a guideline for the additional functionality of the product.  
The user ability ladder is constructed to study the correlation between user ability and home product functions. The user capability study is divided into four modules to comprehensively evaluate the user's capability range, construct a user capability ladder, and comprehensively derive a user behaviour model: user home behaviour clustering and analysis, user perceived capability assessment, user cognitive capability assessment, and user execution capability assessment.  
The model reflects the matching relationship between home product features and user life capabilities in internet interaction, categorising user life capabilities into perceptual, cognitive, and executive capabilities. Home product functionality is divided into home product features (hardware) and interaction form features (software). Users' use of home products requires actual user capabilities, which also regulate the scope of basic home product features. The elderly user group is distinguished from the young group by its phys  
Figure 6: Principle of FCM function–capability matching method.  
iological and psychological influences, weakened abilities, and susceptibility to operational processes. Therefore, it is necessary to coordinate the dynamic influence of all aspects of interaction to achieve a match between the construction of the user ability gradient and the product functionality, which is expressed in the following formula.  
\[FCM=IE(HPF+UC) \tag{5}\]  
where \(FCM\) is the function-capability match, \(IE\) is the internet environment, \(HPF\) is home product features, and \(UC\) is user capabilities. The aim is to build an intelligent home system based on the adaptability between home product features and the living ability of elderly users in the internet environment to improve the quality of the daily life of elderly users and avoid obstacles.