Keywords

1 Introduction

At the start of the 21st century, China stepped into an aging society. It is expected that from 2001 to 2020, the elderly population will soar by an average amount of 5.96 million each year, and the average annual growth rate will be 3.28 %; By 2020, the elderly population will reach 248 million, accounting for 17.17 % of the whole population; By 2050, the numbers will be 483 million and 34.1 % respectively [1]. With acceleration of the aging process, the difficulty and high cost of getting medical treatment caused by insufficiency of medical resources and defection of medical care system are becoming increasingly prominent. However, the promotion of living standard and the changes in people’s self-care awareness and ideas about health lead people to attach importance to disease prevention and health care. Therefore, it is inevitable that traditional medical model consisting mainly of clinical therapy progresses towards diversified comprehensive medical system centering on prevention and combining home nursing and rehabilitation. In this social context, an increasing number of medical rehabilitation products (RP) are ranking among household essentials.

Nevertheless, since the household medical product industry in developing countries is far from mature, barely any design optimization aimed at the elderly’s psychological and physiological traits and behavioral characteristics has been conducted on medical products there. Currently, there is great demand for design research on the interaction and usability of products targeted at the elderly and development of related products.

2 Elderly Users’ Characteristics and Demands for RP Design

  • Physiological Characteristics. Along with increase in human’s age are gradual atrophy of muscles, weakened muscular strength and flexibility of joints, decay in cardiopulmonary function and reduction in exercise endurance, decrease in elasticity and tenacity of bones, and eventually, increase in risk of doing physical exercise. Hence the main purpose of exercises for the elderly should be maintaining endurance and improving stability [2]. Regular limb exercise can postpone the aging process of muscles for the elderly, maintain the flexibility of bones and joints, strengthen blood circulation and improve heart-lung function.

  • Cognitive Function. In the aging brain, reduced cell activity and decelerated central nervous information transmission can take a toll on memory and ability of thinking, and thus ability of comprehension and expression. Compared with the young, it takes more time for the elderly to evaluate the environment, make decisions and adjust their actions accordingly [3]. Interactive products intended for the elderly should adopt simplification in information presentation, i.e. removal of redundant information and functions, to reduce learning cost. Key words and graphics may help the elderly to understand. Repeated demonstration can certainly deepen the elderly’s memory about the interactive process.

  • Psychological Characteristics. We have conducted interviews to gather the elderly’s personal information and information about their family ties, social relationships, rehabilitation training needs and behavioral characteristics. Through analysis of interview results, we have drawn the conclusions that the elderly are generally concerned with their own physical and psychological health, they are inclined to participate in social groups consisting mainly of their peers, they are mentally and physically independent, they are afraid of wide spread of emerging new things, and they sympathize with each other.

Langer from Harvard holds the view that aging is no more than a concept instilled in the minds of the elderly [4]. Her experiments show that one’s rate of aging is closely related to environmental implications. If we can give the elderly appropriate mental hints through products’ function and/or feedback information, it is not beyond the scope of possibility that declinations in their functions be delayed. This is precisely an indispensable property that rehabilitation products should have.

3 Design Principles for Geriatric RP Based on Natural Interaction

In natural interaction, NATURAL refers to users’ feelings when using the products; Natural interaction means operating devices with movements, gestures and language, to ease users of learning and cognition burden and to raise the efficiency of the whole interactive process by appealing to the users’ behavioral habits. Applying natural interaction to geriatric RP design is a fundamental approach to meet the elderly’s demands.

We have formed four design principles of applying natural interaction to geriatric RP design:

  • Accessibility and Safety. Target products should be designed according to the elderly’s physiological and psychological characteristics in order to prevent the elderly from security incidents or potential risk and make the whole process more flexible, more convenient, more comfortable and safer.

  • Suitability. Three aspects of suitability should be considered: suitability of rehabilitative exercise mode, suitability of amount of exercise, and suitability of interactive mode.

  • Experience Consistency and Integrity. Target products should be able to provide users with a complete range of medical diagnostic tests, rehabilitative exercise, healthcare and treatment services through establishment of household medical rehabilitation product system. On the strength of data sharing processes and interlinkages between products, this system should guarantee the users the effective implementation of rehabilitative treatments and offer users with complete and systematic rehabilitative treatment experience.

  • Entertainment and Participation. Natural interaction between users and target products should help the elderly users ease the boredom, physiological fatigue and pressure of exercise, promote communication with other elderly rehabilitative exercise participants, and develop interest in interactive process and exercise result sharing.

4 Design Practice of Geriatric RP Based on Natural Interaction

According to design principles listed above, we have completed the research and design of a rehabilitation product system.

4.1 Choice of Rehabilitative Exercise

There are 6 forms of body movements: flexion, extension, abduction, adduction, rotation, and circumduction [5]. We choose appropriate exercise mode for our product and control the range and frequency of movement to help the users rehabilitating.

Strolling is a common type of exercise and a kind of rehabilitative exercise that is easy to be accepted by the elderly because the body movements involved in strolling are natural and comfortable. We consider the design of rehabilitative exercise from two expects:

  • Convert the joint movements of strolling into rehabilitative exercise based on our product, including the movements of (A) shoulder joint, (B) elbow joint, (C) wrist joint, (D) hip joint, (E) knee joint, and (F) ankle joint as is shown in Fig. 1.

    Fig. 1.
    figure 1

    Design of exercise mode for geriatric rehabilitation products

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  • Adjust, guarantee and control range and frequency of movements and amount of exercise. Since compared with the youth, the elderly probably have weaker sensation of balance and respond more slowly, we adopt this kind of exercise mode that is indoor, fully-monitored and comparatively less likely to bring accidental injury.

4.2 Function Framework of Rehabilitation Product System

The elderly in rehabilitation have various demands, including rehabilitative exercise, management of health information, participation of social activities and entertainment. Therefore, we propose a product function framework as is shown in Fig. 2.

Fig. 2.
figure 2

Function framework and design proposal of rehabilitation product system

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4.3 Construction of Natural Interaction in Rehabilitation Product System

  • Improve users’ perception of elements of human-computer interface. To attain this goal, we amplify sensory stimuli of elements of human-computer interface by changing the environment, time length, intensity and frequency of information feedback [6]. In the aspect of visual feedback, we enlarge the area of information presentation and enhance the contract of characters and graph [7]. In the aspect of auditory feedback, we increase sound volume. In the aspect of tactile feedback, we boost the intensity of vibration. Take operation interface of rehabilitation product system, we choose color black and high contrast to make the controls more recognizable, large buttons to allow easier interaction, and voice broadcast when users switch interfaces to offer information via multiple channels.

  • Add cultural and entertaining elements. By mimicking the color, shape and function design of classic products, our products may give some impact on the nostalgic elderly. Entertaining elements of the product can help the elderly develop interest in rehabilitative process and ease training pressure [8]. Since the main exercise mode offered by target product is based on strolling, we integrate virtual panoramic landscape of multiple scenic spots into the interface to provide the users with different scene at every step and to realize the interaction between users and virtual scene [9].

  • Interlink products and artificial intelligence. Sensor technology allows real-time monitoring of physiological conditions of users while Internet of Things and mobile internet enable the sharing of data. Adaptive capacity and self-learning ability make it possible for the product to react timely to the elderly’s physiological conditions and operant behaviors, offset, to some extent, the elderly’s disadvantage in memorization and reaction [10, 11].

5 Conclusion

Four perspectives should be taken into consideration when designing geriatric rehabilitation products: affordance (relation between an object or an environment and an organism that, through a collection of stimuli, affords the opportunity for that), suitability (form and amount of rehabilitative exercise suit individual users), timeliness of feedback (health data are sent timely to and rehabilitation management system), and entertainment of interactive process (combination of virtual reality and social platform makes rehabilitation interesting). The development and application of natural interaction and digital technology will urge great products that meet fundamental physiological and psychological instead superficial demands to break out.