Dynamic Difficulty Adjustment (DDA) on a Serious Game Used for Hand Rehabilitation

Introduction

Hands play a key role in daily activities. People use them to interact with the world. Nevertheless, due to accidents or medical conditions, people might lose mobility in their hands; consequently, they might require physical rehabilitation.

According to Walsh et al., (2002), “exercise forms a crucial part of a patient’s motor rehabilitation in terms of upper and lower limb function as well as prevention of muscle atrophy” (p. 2).

The main problem in the traditional rehabilitation method is the lack of motivation in patients; therefore, the performances of the rehabilitation exercises might become frustrated and boring. To cope with this issue, robots have been used to assist people during their motor rehabilitation exercises. For instance, a review on robots employed as assistive technologies for rehabilitation on upper limb can be found in (Narayan et al., 2021). In the same vein, robots have been employed for lower limb motor rehabilitation (Alvarez-Perez et al., 2020; Hussain et al., 2017, Hussain et al., 2021).

On the other hand, researchers (Lohse et al., 2013) have studied that video games can be used as a therapeutic tool in physical rehabilitation due to their motivational and engagement properties (e.g., optimal challenge, rewards and feedback provided to the players). As can be seen, these games are focused on assisting people in their rehabilitation processes. These types of games are called serious games. According to Zyda (2005), a serious game can be defined as “a mental contest, played with a computer in accordance with specific rules, that uses entertainment to further government or corporate training, education, health, public policy, and strategic communication objectives” (p. 26).

Figure 1.

Wrist joints

It is important to remark that serious games have been used to assist therapists in the rehabilitation processes of patients on emotional health aspects (e.g., anxiety and depression (Abd-Alrazaq et al., 2022; Barnes & Prescott, 2018; Dias et al., 2018), autism spectrum disorder (Silva et al., 2021; Tsikinas & Xinogalos, 2019), phobias: acrophobia (Sharmili & Kanagaraj, 2020), spider phobia (Lindner et al., 2020)) and motor rehabilitation (e.g. ankle rehabilitation (Hendrickx et al., 2021, Feng et al., 2018), finger rehabilitation (Rahman, 2017; Aguilar-Lazcano & Rechy-Ramirez, 2020), shoulder rehabilitation (Viglialoro et al., 2020; Steiner et al., 2020)), so that the patients could be engaged to the rehabilitation and therapy. Additionally, virtual reality has been used in serious games for upper limb rehabilitation. For instance, Wang et al., (2022) conducted a review on game-based virtual reality systems for upper limb rehabilitation on people that have suffered a stroke to assess the effectiveness of these systems. As a result, authors found that games based on virtual reality for upper limb rehabilitation are more effective than traditional rehabilitation on people suffering cerebral apoplexy.

In terms of wrist motor rehabilitation, the majority of these games are controlled using rehabilitation exercises for the wrist (e.g., flexion, extension, ulnar and radial deviations, pronation and supination of the wrist). The wrist has two main joints, radiocarpal joint and midcarpal joint, that are involved in these rehabilitation exercises (see Figure 1). The intensities of the movements depend on the range-of-motion (ROM) that the patients might have in their hands. According to the American Physical Therapy Association (2001), the range-of-motion “is the arc of motion that occurs at a joint or a series of joints”.