VRun: Running-in-place virtual reality exergame Soojeong Yoo Faculty of Engineering and Information Technologies The University of Sydney, NSW, 2006, Australia
[email protected] ABSTRACT
Exercise is important for health and well-being. However, for some people it can be hard to find the time or motivation to get the recommended amount every day. Exergames on modern gaming consoles have demonstrated potential to address this problem, by helping people stay motivated, which subsequently benefited their health. Fully-immersive virtual reality has the potential to achieve similar benefits. In this paper we present VRun, a virtual reality exergame developed for Google Cardboard. The game requires the user to physically run through a virtual world, with activity detected through the smartphone’s accelerometer. We performed an evaluation of the game in three different formats, comparing virtual reality with a large wall display and a baseline laptop. This is the first evaluation of a running-in-place virtual reality exergame. Author Keywords
Virtual Reality, Smartphone, Google VR, Running-on-thespot, Immersion, Exergame. ACM Classification Keywords
H.5.1. [Multimedia Information Systems]: Artificial, augmented, and virtual realities – Miscellaneous. INTRODUCTION
Exercise is important. For example, exercising, even for 10 minutes, can have valuable cognitive benefits, temporarily increasing concentration (Klein & Simmers 2009). The US National Heart, Lung and Blood institute reports that barriers to physical activity include lifestyle, lack of nearby safe recreational facilities, health conditions, and age (NIH 2012). Exergaming has the potential to help overcome sedentary lifestyles (Klein & Simmers 2009). It combines video games and exercise, making the physical activity more interesting or “fun”. Game consoles such as the Nintendo Wii (Park et al. 2014) and the Microsoft Kinect (Chan et al. 2011) have exergames which have demonstrated they can help people Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from
[email protected]. OzCHI '16, November 29-December 02, 2016, Launceston, TAS, Australia Copyright is held by the owner/author(s). Publication rights licensed to ACM. ACM 978-1-4503-4618-4/16/11…$15.00 DOI: http://dx.doi.org/10.1145/3010915.3010987
Judy Kay Faculty of Engineering and Information Technologies The University of Sydney, NSW, 2006, Australia
[email protected] be active while they have fun. Recently, the growing maturity of virtual reality (VR) technology has enabled VR exergaming. For example, Tuveri et al., (2016) utilised an exercycle and an Oculus Rift with gamification aspects such as trophies to motivate player. Using VR has benefits over traditional exergames that use desktop or large displays as it has the potential to feel more immersive. However, VR head-mounted displays (HMDs) like the Oculus Rift and HTC Vive must be tethered to a computer, decreasing the portability. A potential solution to portability issues of popular HMDs is Smartphone VR (Hoberman et al. 2012). They are lightweight and portable compared to other HMD’s (Desai et al. 2014), as they rely only on the motion sensors in the smartphone to perform head tracking, therefore eliminating the need for external tracking cameras. This type of HMD has become readily available since Google released Google Cardboard. It is notable for low cost, portability and the growing support for developers, where SDKs are available to create native Android apps or apps with Unity, deploying to both Android and iOS. In this work, we explore how to harness the potential of low cost VR, such as Google cardboard, for exergaming. We developed a prototype called “VRun”, which uses the smartphone accelerometer sensor to detect the user as they run on the spot, to move through a virtual world. We performed a lab study of the prototype with a smartphone VR Google Cardboard HMD compared with two other conditions to gain insights into the following research questions: RQ1. Can we create an immersive exergame experience based on running on the spot? RQ2: How does the immersiveness of the VRun experience compare with the 3 different displays? Our key contribution is the first study of a VR exergame involving running on the spot. We assessed its immersiveness and viability for exercising compared with two other display conditions: (1) laptop display, as it is such a widely available format and will serve as a baseline; (2) large wall display, which is a semi-immersive and pervasive type of display. RELATED WORK
The term, virtual reality, is shifting. It used to include applications displayed on a desktop display, a large display, or a virtual reality headset, also known as a headmounted display or HMD (Rizzo et al. 2011; Fällman et al. 1999). However, it is coming to mean just the last. As our
work incorporates all three types of displays, this section provides examples of exergames from the previous work for each of these types of displays. Desktop display The Nintendo Wii gaming console has been very popular for sport games in particular, utilizing accessories such as the Wiimote and the balance board. Much of the research on the Nintendo Wii’s fitness applications have focused on the elderly (Park et al. 2014; Laufer et al. 2014). For example, the balance board accessory proved effective in helping elderly people regain or improve their balance, thus reducing the risk of falls (Duque et al. 2013). This made it a useful tool for clinicians as it can aid in improving dynamic balance and balance confidence in the elderly. Large display In South Korea, due to the high cost of greens fees and of travel to outdoor golf courses, many people play on screens at golf cafés (Han et al. 2014). There is an estimated 5,000 screen golf cafés and 175 physical golf courses. Screen golf is played indoors, in private rooms with large projected screens and a simulated golf course displayed. Players use real golf clubs and balls, aiming at the screen. The balls are tracked, and the speed, impact and orientation determines where the ball will land in the virtual world. Head-mounted display An example of a fully-immersive exergame allowed players to ride through a virtual world using an Oculus Rift (Shaw et al. 2015). Interaction relied on a combination of an exercise bike that the player could physically pedal to traverse through the virtual world and a Kinect to detect the player’s motion, such as leaning and ducking to avoid obstacles. The results of the study indicated that the VR game significantly increased the participant’s enjoyment and motivation compared to traditional laptop display.
as possible. The one difference between the conditions was that the laptop and large display modes required the user to have a smartphone in their pocket to detect steps. This was necessary as these modes did not require a HMD. These modes were run on a laptop that hosted a websockets server for the smartphone to stream the step data. Interface The game continuously displays the step count and time elapsed as seen in the sky in Figure 1 where the user has taken 11 steps and the play time is 1.45 minutes. In addition to this, a message appears if the player runs in the wrong direction as they may not otherwise realise this.
Figure 1. Screenshot from the HMD version with the step count and time displayed in the player’s vision.
For this first exploration of a running-in-place VR exergame, we chose a simple mode of play, where the player only runs in one direction. Each physical step a user takes is detected through the smartphone’s accelerometer using Unity’s Input class and the value is then filtered to detect step pulses. The player’s movement speed is then calculated by the frequency of the steps, which moves the player forwards in the virtual world.
We go beyond this work, to study running-in-place. This is appealing as it requires no special equipment such as an exercycle. It was proposed by Nilsson et al. (2016) as it can be performed in places with limited space, such as offices. To our knowledge there has been only one initial feasibility study that investigated using the accelerometer of the smartphone to detect walking in place, and linking this to the user’s movement through a fully-immersive virtual world (Tregillus 2016). The focus of that work was on the technology proof-of-concept rather than evaluating people’s assessment of its immersiveness in an exergame. DESIGN AND DEVELOPMENT OF “VRUN”
VRun is a fully-immersive VR exergame, using Google Cardboard, for to its low cost, availability and portability (Yoo & Parker 2015). The design is inspired by popular arcade games such as Frogger and Crossy Road, where players aim to beat their previous personal best score. We used a HTC One with a plastic version of the Google Cardboard. VRun was developed in the Unity 5 game engine utilising the Google VR plugin. We created three versions of VRun, one for each display type described in the related work above. We aimed to gain insights into the benefits of head-mounted display compared with the two other display types. So, our implementation ensured that all display types had as similar an interface and interaction
Figure 2. Overview of the VRun level.
This game has one level with 10 pre-defined obstacles in the way of the finish line (Figure 2). The user starts at the bottom of the screen (labelled Start zone) and aims to get to the top area, labelled Finish line. The obstacles include: fireballs, arrows, rolling spikes, saws, and blobs (coloured
Figure 3. (a) Laptop display; (b) Large display; (c) Head-mounted display(HMD).
dots) that run across the level from the left or right. The goal of the player is to get to the finish line as fast as they can without colliding with any of the obstacles. To avoid the obstacles, the player should either stop and wait for it to pass or run faster to beat it.
multiples of 6 participants. The choice of 18 participants was chosen as the study progressed. As our goals were primarily to gain qualitative insights, we needed enough participants to reach saturation in observations and this occurred with the third set of 6 participants.
After passing each obstacle, the player enters a safe row where there are no obstacles, allowing them to either rest or prepare for crossing the next row.
RESULTS
STUDY DESIGN1
We designed a study to answer our two research questions, outlined in the introduction. We designed a within-subject user study, where participants used VRun in all three display conditions: Laptop display (Figure 3a), Large display (Figure 3b), and HMD (Figure 3c). In each condition, there was no time limit; participants could stop at any time and move on to the next condition, regardless of whether they successfully completed the game. The order was varied across subjects to give balanced order of use, to account for potential order effects. While participants were using each display type we recorded their steps, the number of times they replayed, the total time spent in each display type, and the types they finished the game with. Following the trial of each display type, participants completed the System Usability Scale (SUS) Questionnaire. We chose this as it has been widely used, providing a calibrated measure of usability. This is important for interpreting the other data since low usability could compromise immersiveness. We collected qualitative feedback through interviews, at the very end of all three conditions, to seek participants’ perception of the immersiveness of VRun and whether they felt it exerted them. EXPERIMENT
VRun was tested and evaluated by 18 participants (female: 7, male: 11), all staff and students at the University of Sydney with either an IT, psychology or education background. They were aged between 18 and 45 (average: 28). Eleven had used VR before and four had used VR more than 5 times. The order randomisation required 1
This study was conducted under the University of Sydney ethics approval number: 2016/089, approved on the 14th April 2016.
This section presents data from SUS surveys, logs, interviews, and observations. All comments were categorised into themes that emerged from our grounded analysis of participant comments in the interview. The number of successes in the game was similar for HMD and Large display modes, 7 and 6 respectfully. The Laptop display mode had a low number, 2. Six participants did not complete any of the three modes. There were two participants who completed the game on the laptop display mode but did not complete the large display mode. Both were IT students and had used VR more than five times. In terms of the order, both played at the large display mode first. Therefore, it might be that they saw this as warming up and learning the gameplay. Overall, the average SUS score was 68, making it an average usability score. The Laptop display averaged 70, and the HMD 75. The large display scored 65. Every participant commented that the large screen was immersive, but they could not see themselves using it in their everyday life as it is too big. The Laptop and HMD modes were considered more practical. In general, participant response to the game as a whole was positive. Participants appreciated the virtual world, commenting particularly on the graphic quality and use of colour. Participants were motivated to reach the finish line as one participant commented: “obstacles made me run faster – particularly the fireballs”. Laptop Display The small nature of the laptop screen drew criticisms as it was too small to see obstacles coming. Also, participants disliked the fact that, unlike the VR mode, they could not look around freely.
However, one participant commented that they would like to use the game on a laptop as they do not have a largescreen or a HMD. Large display The interactive large screen provided participants with wider visuals than the laptop. However, they could not look around in 360 degrees. Despite this, participants appreciated the size, as they could see more of the environment which allowed them to judge the distance and speed. It was also easier on the eyes, “it was more immersive without the strain on my eyes compared to the laptop screen”. HMD Compared to the previous two modes, participants could look around the scene in 360 degrees. This meant the obstacles could be clearly seen and participants could strategize carefully when it was safe to run. The immersive nature of the display was appreciated, with a participant commenting “immersive VR makes me feel like I am inside the game, which is a good experience” while another mentioned “best of the three, gave the ability to look and see as well as move”. As an exergame, VRun was well received, with 10 participants stating that the game made exercise fun as it was combined entertainment. For example, one said that it was a “fun way to exercise, with the goal to reach the destination”. Notably, every participant commented that they had exerted themselves. For example: “it is comparable to a workout, but made me less tired than physically running”. Additionally, one participant mentioned that they would not need to visit the gym if they had this system. Convenience was also mentioned by 9 participants, “I don’t need to go anywhere to exercise”, and “having this game would allow me to go outside and have a minute walk on the spot anywhere”. This indicates that participants valued the flexibility and availability of VRun. Improvements and limitations
Participants made suggestions on how to improve interaction with the game. The most important related to the accuracy of the activity tracking. This was a problem when they ran faster to try to avoid an obstacle but the game did not seem to respond by moving through the virtual world fast enough to avoid obstacles. Other suggestions included personalisation based on an individual’s needs, such as altering the exercise for a person with an injury. Another suggestion was to provide incentives such as coins or items won. Two participants wanted to be able to move backwards to escape obstacles, something the current approach does not support. For the laptop and large display modes, two participants found the phone too big to hold or put in a pocket. They suggested that an armband or other tracking sensor such as a smartwatch would be more comfortable. One participant specifically mentioned that the HMD was more sensitive to their body when they were running. We observed that every participant moved around the physical room without realising it. Nor did they want to hold a chair to avoid this. The researcher had to alert them to avoid
moving. This indicates a serious limitation for smartphone VR. Some technology limitations emerged. The first was the viewpoint slowly drifting, due to gyroscope drift in the smartphone. The second limitation related to the fit of the HMD. It was not tight enough for all the participants. These participants commented that the HMD bouncing was distracting. This could be resolved by fitting the HMD and smartphone tighter and wrapping the strap around the back of the user’s head. Another limitation was in streaming the accelerometer data from the smartphone to the laptop for both laptop and large modes. The accelerometer information was streamed over WiFi, which caused an occasional lag during use. This resulted in footsteps not being detected reliably, which subsequently slowed progress through the virtual world. DISCUSSION
Overall, the results were promising in terms of the immersion for both the large display and HMD. Each had benefits. The head-mounted display avoided latency problems and allowed the user to view the virtual world in 360 degrees. The large display type, however, could be played longer without the need to wear a HMD, and it still felt immersive due to its large size. While participants saw benefits of laptop display mode for its portability and availability, its screen was too small for this use, making it hard to see incoming obstacles. Despite intermittent latency problems and errors in the step tracking, every participant felt that this game exerted them and would be useful in some contexts. The gamified elements added another dimension to the exercise, motivating them to complete the level. Participant feedback also indicated that this system made exercise fun and would be a convenient way to exercise that can be performed anywhere. CONCLUSION
In this paper we presented VRun, a virtual reality running exergame that allows players to physically run on the spot to move through a virtual world. We ran a within-subject study comparing three conditions (Laptop, Large display and HMD). The results point to the potential for our fullyimmersive VRun exergame to engage people, particularly those who cannot visit the gym regularly, allowing them to perform the exercise anywhere. Additionally, participants found the large display immersive due to its large size. It also avoided the cumbersome headset. This may make it more acceptable for longer exercise periods. ACKNOWLEDGMENTS
We would like to thank the staff and students who participated in this study. REFERENCES
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