Keywords

1 Introduction

Many applications have been built around devices emitting and receiving signals of infrared light. In 2008, Johnny Chung Lee showed the potential of using the Nintendo Wiimote control, a receiver of infrared light, for the purposes of creating a low-cost interactive whiteboard [1]. Similarly, Joa Ebert and Thibault Imbert developed a programming library called Action Script 3 Wiiflash, which allows connecting the Wiimote to the computer to generate applications or control movements based games [2]. These achievements have enabled low-cost body-computer interaction scenarios, where the movement of a person is transformed into a computer action. Such applications can clearly be extended beyond entertainment and support other goals such as physical therapies based on motivating body movements.

Physiotherapy is a resource that is used in the treatment of children with cerebral palsy (CP), in order to maintain or improve their capacity of movement; thus depending on the particular scenario presented by a child with this type of brain disorder, a physiotherapist might apply different physical exercises. Regardless of the mental-physical situation held by the patient, all exercises involve muscle strain. The exercises of muscle strain are activities requiring great physical effort and often causing pain and discomfort in children; and by being a repetitive activity, they may produce boredom. The pain, discomfort and the boredom related to practicing these exercises become factors that cause children to seek to leave such therapies.

This paper presents the results of designing, implementing and evaluating a bone movement-tracking computer application for supporting muscle strain therapies by children with CP, which is both inexpensive and easy to use. Our design is based on the use of a Wiimote control and an infrared signal, which is emitted by a secondary control, which moves and produces an action on the computer screen. Based on our results we can argue that the usefulness of this basic interaction is likely to increase motivation and the effort made by children with cerebral palsy, while performing muscle strain exercises during physical therapies.

2 The Concept

One challenge commonly encountered in the work with children with cerebral palsy is to capture and hold their attention while performing any activity. However, this lack of attention does not always occur when interacting with a computer. Thus, a good alternative to work with these children is to try to include activities based on computer devices that attract their attention as a result of the interaction [3].

Furthermore, considering that pain, physical exertion and boredom are the components that produce nuisance and abandonment of physical therapies by children, the main idea of this project was to create a playful multimedia system, which provides physical therapists with a tool that allows them to apply muscle strain exercises in a nice and simple way. The implicit goal of our design is to get the child to play while doing physical therapy. Likewise, our system was designed to be adapted to different levels of patients’ motor skills as there is variation on them.

Finally, our design considers that the use of multimedia elements within therapies could generate a “biofeedback” where the children with cerebral palsy associate the movement of their body with possible events that are raised on a screen [4].

3 Materials

3.1 Wiimote and Wiiflash

For this project we used the Nintendo Wiimote control, which has a receiver of infrared light to detect up to four lights of this type, and based on that determining its position on a screen. With respect to programming the applications, this was done using a library of Action Script 3 Wiiflash. We also used the Wiiflash server program that allows the connection between the computer and Wiimote [2].

3.2 Controls

Given that the level of spasticity in children with cerebral palsy is not always the same, the control system that we designed avoids the use of buttons and complex gestures. Moreover, given its size, it allows to be placed in different parts of the body to facilitate its use.

The controls that we developed are based on a simple circuit where a 1.5-volt battery uses a pulsing switch to turn an infrared LED. Based on this principle two designs for the control device were defined and are described in the following lines (Fig. 1).

Fig. 1.
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Basic operation of the control circuit

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Control Type One.

For this model of control, the idea was to produce a rectangular shape that has a minimum size, which allows it to be placed in different parts of the body by means of Velcro straps, handles or headbands. The materials used in this control are a piece of plastic (box), 2 cm by 4 cm and 1.5 cm thick, which served as a box in which it is installed an infrared LED connected to a watch battery of 1.5 volts and a switch (Fig. 2).

Fig. 2.
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Image of control type one

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Control Type Two.

For the form of this control the idea was to think on an exercise based on riding a bicycles and how it can be achieved. The idea and motivation for designing this type of control is because existing machines on the market have a high cost. With regard to the materials used to manufacture this control, we used wood (mdf) 15 mm to generate the case and in this where an axis passing through a bearing with smaller pivots. The movement generates a pulse that in once turned on the light generating interaction with the application on the screen (Fig. 3).

Fig. 3.
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Control type two mechanism

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4 Applications

The applications we designed were defined from our analysis of the basic muscle strain exercises that we observed being applied in physical therapies. Thus it has sought to take into account the three body parts that generate most of the movements: the head, arms and legs.

4.1 Application 1 – Shooting Game

The exercise of distended arms for children with CP comprises an activity of flexion and extension that seeks to relax the muscles of the limb. Thus we created a target shooting game where the child must perform this exercise (flexion and extension of arm) to achieve shooting an arrow into a target displayed on screen (Fig. 4).

Fig. 4.
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Arm distension exercise

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Application Operation.

The application is controlled by two main components of interface where in the first instance, the therapist is the one who controls and defines the complexity of the exercise through activation buttons (G) for accelerating the speed at which the target moves. The physical therapist can restart the game at any time by pulsing a button (H). The therapist interacts with the application via the computer mouse (Fig. 5).

Fig. 5.
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Shooting game interface: (A) Cursor, (B) Executor of action, (C) Game control, (D) Score, (E) Wiimote info, (F) Level of difficulty, (G) Selection of difficulty, (H) Restart button, (I) Connection indicator.

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In the second interface (main area depicting a kid with an arch), the cursor (A) is controlled by the IR remote that is manipulated by the patient. The patient attempts to drag the cursor to the executor of action (B) for this to move up to a distance limit from where the action of shooting the arrow at a fixed target or a target that is moving will be done.

The use of such controls and tracking system of bone structure allows the exercise to change in complexity and how it is performed depends on the location and rotation of the Wii control with respect to infrared control.

In Fig. 6, the moving distance (y) achieved by the patient is a function of (x) the distance between the Wiimote and the patient.

Fig. 6.
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Interaction of the controls (1. Patient, 2. Infrared control, 3. Screen, 4. Wiimote)

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If the control is rotated, the arrangement or interaction of the exercise changes since it depends on its rotation. Consequently, exercises can be done from left to right, right to left, top-down or bottom-up. This allows the same application to change the way in which it runs in a simple way providing so much flexibility for applications requiring it (Fig. 7).

Fig. 7.
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Wiimote control rotation

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4.2 Application 2 – Bicycle Simulation

In muscle strain exercises, the therapists apply leg flexion and extension, where the work done simulates the action of pedaling, but in a horizontal position (the patient laying on a surface) (Fig. 8).

Fig. 8.
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Legs distension exercise

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Application Operation.

This application simulates a bicycle race to motivate the child with CP to perform an exercise where stretching and contraction of legs is achieved within the context of a leg pedaling action on a bicycle. The interface of this game is controlled by two users: the child and the physiotherapist. Thus the physiotherapist is who can control the level of difficulty application (F), while they can also determine when the game starts or restarts using the button (G). The child, once the game has started, should start pedaling so the figure on the screen (A) starts to move up to the checkered flag. The control that we designed for this game has a base with pedals that allows the exercise to be conducted from a chair or wheel chair depending on the case. This control also has the facility to adjust the length of the pedal lever to adjust it to the length of the children’s legs. Although some children with cerebral palsy cannot move their legs, this stretch is also applicable to them since they must avoid muscle spasticity. If this were the case, this application could run assisted by the therapist (Fig. 9).

Fig. 9.
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Bicycle simulation game interface: (A) Player, (B) Time counter, (C) Text field, (D) Wiimote info, (E) Difficulty level, (F) Selection of difficulty, (G) Restart button, (H) Connection Indicator.

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4.3 Application 3 – Pick a Color Game

Although the head is not considered an extremity (tip), it is a joint body part, which in the treatment of cerebral palsy should be exercised to avoid having bad posture, which might result on other problems. That is why we designed an application in which there is a dynamic movement of the head as the main mechanism of interaction (Fig. 10).

Fig. 10.
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Head movement

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Application operation

This application (Fig. 11) seeks to exercise the head with an associative game of shapes and colors where the child can indicate the color of a fruit by moving his head; the game can also be controlled by using the arms. The interface requires the physiotherapist to use the selector (E) to define a fruit that appears on the board (C) and thus the child moves the cursor (A) to set the color of the fruit selected.

Fig. 11.
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Pick a color game interface. (A) Cursor, (B) Text field, (C) Whiteboard, (D) Wiimote info, (E) Selector, (F) Restart button, (G) Connection indicator, (H) Color Palette (Color figure online).

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5 Results

The results of this research have been satisfactory since it has been possible to see the benefits of a therapy based in the implementation of a bone movement-tracking system as the Wiimote. Through a series of tests with twelve children (9 with limited CP and 3 with high CP) at the Instituto Stephen Hawking in Cuenca, Ecuador, we noticed that running a therapy for a child with CP based on a fun application, helped them to perform better their exercises of muscle strain, kept them motivated and they began to lose their fear of this type of therapy. Figures 12 and 13 shows pictures of one of the children performing the activities.

Fig. 12.
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Application testing

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Fig. 13.
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Application testing

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Similarly, the simple and friendly interaction that is created between the child and the application allows a reaction from the brain where it can learn how to make a body part to react for a certain activity.

The possibility that this bone movement-tracking system could be adapted to different degrees of motor skills gives our design flexibility to support different types of applications that pursue other learning or communication purposes.

One point that should be made clear, is that the application of this technology within physiotherapy of children with CP, does not seek to displace or replace the activity of the physical therapists, but rather, one should consider that this technology is a tool to support their work.

6 Conclusions

For the treatment of cerebral palsy there are several therapies, where it is intended that the child with a brain affected, depending on the degree of affection they have, can learn to perform certain activities based on perception and motor development. Because of this, the motivation that a child may have plays a very important role in the rehabilitation; thus games can become a necessary tool and ally for the creation of effective therapeutic activities.

This research project has revealed that the implementation of a Bone movement-tracking system, as is the Wiimote, within the physiotherapy which applies to children with cerebral palsy, can be effective because beyond the benefit of providing a fun method for exercises which usually (in the traditional way) can be annoying or boring, you can generate a neuro-perception based on where the brain learns and relates a movement with a learning event.

The applications that we designed for this research have shown a good level of effectiveness, because during the tests we performed it has been noted an increase in motivation and effort put by children to perform relaxation exercises.

In addition, we can see that the cost to build the controls that are required for the applications is low compared to the others machines and tools used in physical therapy. An advantage that has been found in the creation of these applications is that infrared controls that are used to detect the movement can be of any shape while an infrared light is lit and can be detected by the Wiimote.

The use of this type of controls and intuitive interfaces, allows the development of applications that can be adapted to different cases or levels of motor skills experienced by children with cerebral palsy. This becomes an advantage in comparison to other solutions that are usually designed and defined from fixed anthropometric and ergonomic requirements.