Locomotion Interface Research Articles

Leaning-Based Interfaces Improve Simultaneous Locomotion and Object Interaction in VR Compared to the Handheld Controller.

Physical walking is often considered the gold standard for VR travel whenever feasible. However, limited free-space walking areas in the real-world do not allow exploring larger-scale virtual environments by actual walking. Therefore, users often require handheld controllers for navigation, which can reduce believability, interfere with simultaneous interaction tasks, and exacerbate adverse effects such as motion sickness and disorientation. To investigate alternative locomotion options, we compared handheld Controller (thumbstick-based) and physical walking versus a seated (HeadJoystick) and standing/stepping (NaviBoard) leaning-based locomotion interface, where seated/standing users travel by moving their head toward the target direction. Rotations were always physically performed. To compare these interfaces, we designed a novel simultaneous locomotion and object interaction task, where users needed to keep touching the center of upward moving target balloons with their virtual lightsaber, while simultaneously staying inside a horizontally moving enclosure. Walking resulted in the best locomotion, interaction, and combined performances while the controller performed worst. Leaning-based interfaces improved user experience and performance compared to Controller, especially when standing/stepping using NaviBoard, but did not reach walking performance. That is, leaning-based interfaces HeadJoystick (sitting) and NaviBoard (standing) that provided additional physical self-motion cues compared to controller improved enjoyment, preference, spatial presence, vection intensity, motion sickness, as well as performance for locomotion, object interaction, and combined locomotion and object interaction. Our results also showed that less embodied interfaces (and in particular the controller) caused a more pronounced performance deterioration when increasing locomotion speed. Moreover, observed differences between our interfaces were not affected by repeated interface usage.

Locomotion Techniques for Dynamic Environments: Effects on Spatial Knowledge and User Experiences.

Various locomotion techniques are used to navigate and find way through space in virtual environments (VE), and each technique provides different experiences and performances to users. Previous studies have primarily focused on static environments, whereas there is a need for research from a different perspective of dynamic environments because there are many moving objects in VE, such as other users. In this study, we compare the effects of different locomotion techniques on the user's spatial knowledge and experience, depending on whether the virtual objects are moving or not. The investigated locomotion techniques include joystick, teleportation, and redirected walking (RDW), all commonly used for VR navigation. The results showed that the differences in spatial knowledge and user experience provided by different locomotion techniques can vary depending on whether the environment is static or dynamic. Our results also showed that for a given VE, there are different locomotion techniques that induce fewer collisions between the user and other objects, or reduce the time it takes the user to perform a given task. This study suggests that when designing a locomotion interface for a specific VR application, it is possible to improve the user's spatial knowledge and experience by recommending different locomotion techniques depending on the degree of environment dynamism and and type of task.

Redirected Walking on Omnidirectional Treadmill.

Redirected walking (RDW) and omnidirectional treadmill (ODT) are two effective solutions to the natural locomotion interface in virtual reality. ODT fully compresses the physical space and can be used as the integration carrier of all kinds of devices. However, the user experience varies in different directions of ODT, and the premise of interaction between users and integrated devices is a good match between virtual and real objects. RDW technology uses visual cues to guide the user's location in physical space. Based on this principle, combining RDW technology with ODT to guide the user's walking direction through visual cues can effectively improve user experience on ODT and make full use of various devices integrated on ODT. This paper explores the novel prospects of combining RDW technology with ODT and formally puts forward the concept of O-RDW (ODT-based RDW). Two baseline algorithms, i.e., OS2MD (ODT-based steer to multi-direction), and OS2MT (ODT-based steer to multi-target), are proposed to combine the merits of both RDW and ODT. With the help of the simulation environment, this paper quantitatively analyzes the applicable scenarios of the two algorithms and the influence of several main factors on the performance. Based on the conclusions of the simulation experiments, the two O-RDW algorithms are successfully applied in the practical application case of multi-target haptic feedback. Combined with the user study, the practicability and effectiveness of O-RDW technology in practical use are further verified.

A Deep Learning Approach for Biped Robot Locomotion Interface Using a Single Inertial Sensor.

In this study, we introduce a novel framework that combines human motion parameterization from a single inertial sensor, motion synthesis from these parameters, and biped robot motion control using the synthesized motion. This framework applies advanced deep learning methods to data obtained from an IMU attached to a human subject's pelvis. This minimalistic sensor setup simplifies the data collection process, overcoming price and complexity challenges related to multi-sensor systems. We employed a Bi-LSTM encoder to estimate key human motion parameters: walking velocity and gait phase from the IMU sensor. This step is followed by a feedforward motion generator-decoder network that accurately produces lower limb joint angles and displacement corresponding to these parameters. Additionally, our method also introduces a Fourier series-based approach to generate these key motion parameters solely from user commands, specifically walking speed and gait period. Hence, the decoder can receive inputs either from the encoder or directly from the Fourier series parameter generator. The output of the decoder network is then utilized as a reference motion for the walking control of a biped robot, employing a constraint-consistent inverse dynamics control algorithm. This framework facilitates biped robot motion planning based on data from either a single inertial sensor or two user commands. The proposed method was validated through robot simulations in the MuJoco physics engine environment. The motion controller achieved an error of ≤5° in tracking the joint angles demonstrating the effectiveness of the proposed framework. This was accomplished using minimal sensor data or few user commands, marking a promising foundation for robotic control and human-robot interaction.

Strolling in Room-Scale VR: Hex-Core-MK1 Omnidirectional Treadmill.

The natural locomotion interface is critical to the development of many VR applications. For household VR applications, there are two basic requirements: natural immersive experience and minimized space occupation. The existing locomotion strategies generally do not simultaneously satisfy these two requirements well. This article presents a novel omnidirectional treadmill (ODT) system named Hex-Core-MK1 (HCMK1). By implementing two kinds of mirror-symmetrical spiral rollers to generate the omnidirectional velocity field, this proposed system is capable of providing real walking experiences with a full-degree of freedom in an area as small as 1.76 m 2, while delivering great advantages over several existing ODT systems in terms of weight, volume, latency and dynamic performance. Compared with the sizes of Infinadeck and HCP, the two best motor-driven ODTs so far, the 8 cm height of HCMK1 is only 20% of Infinadeck and 50% of HCP. In addition, HCMK1 is a lightweight device weighing only 110 kg, which provides possibilities for further expanding VR scenarios, such as terrain simulation. The system latency of HCMK1 is only 9ms. The experiments show that HCMK1 can deliver a starting acceleration of 16.00 m/s 2 and a braking acceleration of 30.00 m/s 2.

Influence of Robot-Assisted Gait Training on Lower-Limb Muscle Activity in Patients With Stroke: Comparison With Conventional Gait Training.

To measure muscle activity before and after robot-assisted gait training (RAGT) in patients with stroke and examine the differences in muscle activity changes compared with conventional gait training (CGT). Thirty patients with stroke (RAGT group, n=17; CGT group, n=13) participated in the study. All patients underwent RAGT using a footpad locomotion interface or CGT for 20 minutes for a total of 20 sessions. Outcome measures were lower-limb muscle activity and gait speed. Measurements were performed before the start of the intervention and after the end of the 4-week intervention. The RAGT group showed increased muscle activity in the gastrocnemius, whereas the CGT group showed high muscle activity in the rectus femoris. In the terminal stance of the gait cycle, the gastrocnemius, the increase in muscle activity was significantly higher in the RAGT group than in the CGT group. The results suggest that RAGT with end-effector type is more effective than CGT to increase the gastrocnemius muscle activity.

Leaning-based interfaces improve ground-based VR locomotion in reach-the-target, follow-the-path, and racing tasks.

Using standard handheld interfaces for VR locomotion may not provide a believable self-motion experience and can contribute to unwanted side effects such as motion sickness, disorientation, or increased cognitive load. This paper demonstrates how using a seated leaning-based locomotion interface --HeadJoystick-- in VR ground-based navigation affects user experience, usability, and performance. In three within-subject studies, we compared controller (touchpad/thumbstick) with a more embodied interface ("HeadJoystick") where users moved their head and/or leaned in the direction of desired locomotion. In both conditions, users sat on a regular office chair and used it to control virtual rotations. In the first study, 24 participants used HeadJoystick versus Controller in three complementary tasks including reach-the-target, follow-the-path, and racing (dynamic obstacle avoidance). In the second study, 18 participants repeatedly used HeadJoystick versus Controller (8 one-minute trials each) in a reach-the-target task. To evaluate potential benefits of different brake mechanisms, in the third study 18 participants were asked to stop within each target area for one second. All three studies consistently showed advantages of HeadJoystick over Controller: we observed improved performance in all tasks, as well as higher user ratings for enjoyment, spatial presence, immersion, vection intensity, usability, ease of learning, ease of use, and rated potential for daily and long-term use, while reducing motion sickness and task load. Overall, our results suggest that leaning-based interfaces such as HeadJoystick provide an interesting and more embodied alternative to handheld interfaces in driving, reach-the-target, and follow-the-path tasks, and potentially a wider range of scenarios.

Teleporting through virtual environments: benefits of navigational feedback and practice

Virtual environments (VEs) can be infinitely large, but movement of the virtual reality (VR) user is constrained by the surrounding real environment. Teleporting has become a popular locomotion interface to allow complete exploration of the VE. To teleport, the user selects the intended position (and sometimes orientation) before being instantly transported to that location. However, locomotion interfaces such as teleporting can cause disorientation. This experiment explored whether practice and feedback when using the teleporting interface can reduce disorientation. VR headset owners participated remotely. On each trial of a triangle completion task, the participant traveled along two path legs through a VE before attempting to point to the path origin. Travel was completed with one of two teleporting interfaces that differed in the availability of rotational self-motion cues. Participants in the feedback condition received feedback about their pointing accuracy. For both teleporting interfaces tested, feedback caused significant improvement in pointing performance, and practice alone caused only marginal improvement. These results suggest that disorientation in VR can be reduced through feedback-based training.

A Wheelchair Locomotion Interface in a VR Disability Simulation Reduces Implicit Bias.

This research investigates how experiencing virtual embodiment in a wheelchair affects implicit bias towards people who use wheelchairs. We also investigate how receiving information from a virtual instructor who uses a wheelchair affects implicit bias towards people who use wheelchairs. Implicit biases are actions or judgments of people towards various concepts or stereotypes (e.g., races). We hypothesized that experiencing a Disability Simulation (DS) through an avatar in a wheelchair and receiving information from an instructor with a disability will have a significant effect on participants' ability to recall disability-related information and will reduce implicit biases towards people who use wheelchairs. To investigate this hypothesis, a 2x2 between-subjects user study was conducted where participants experienced an immersive VR DS that presents information about Multiple Sclerosis (MS) with factors of instructor (i.e., instructor with a disability versus instructor without a disability) and locomotion interface (i.e., without a disability - locomotion through in-place-walking, with a disability - locomotion in a wheelchair). Participants took a disability-focused Implicit Association Test two times, once before and once after experiencing the DS. They also took a test of knowledge retention about MS. The primary result is: experiencing the DS through locomotion in a wheelchair was better for both the disability-related information recall task and reducing implicit bias towards people who use wheelchairs.

Haptic Ankle Platform for Interactive Walking in Virtual Reality

This article presents an impedance type ankle haptic interface for providing users with an immersive navigation experience in virtual reality (VR). The ankle platform, actuated by an electric motor with feedback control, enables the use of foot-tapping gestures to create a walking experience like a real one and to haptically render different types of walking terrains. Experimental studies demonstrated that the interface can be easily used to generate virtual walking and is capable of rendering terrains, such as hard and soft surfaces, and multi-layer complex dynamic terrains. The designed system is a seated-type VR locomotion interface, therefore allowing its user to maintain a stable seated posture to comfortably navigate a virtual scene.

Investigation of the turning speed for immersive environments using freehand‐based technique

AbstractDesigning a natural, usable, and efficient gesture‐based virtual locomotion interface in immersive environments has been challenging. Freehand‐based virtual locomotion technique (VLT) has the advantage of eliminating the need to see the handhold devices and has been implemented in many applications. Translation control and direction control are two essential components of freehand‐based VLT; however, the transfer function of turning speed in direction control has not been well explored. In this article, we systematically investigate the effects of turning speed on freehand‐based virtual locomotion for the first time. A transfer function that maps the position of the hand to the turning speed is defined, and three parameters related to the turning speed are investigated. In the experiment, participants are asked to travel in the virtual environment from a first‐person perspective with different parameters. Statistical analysis of the experimental results reveals the relationship between the turning speed and the traveling performance as well as the traveling experience.

Effect of gait rehabilitation with a footpad-type locomotion interface on gait ability in subacute stroke patients.

Gait rehabilitation using a footpad-type locomotion interface has been reported as effective in improving gait ability in chronic stroke patients. However, the effect on subacute stroke patients is unknown. To compare the effect of gait rehabilitation using a footpad-type locomotion interface (Gait Training with Locomotion Interface group; GTLI group) with conventional gait rehabilitation (control group) in subacute stroke patients. Twenty-one stroke patients (GTLI group: n = 13, control group: n = 8) participated in the study. All participants received gait rehabilitation using the footpad-type locomotion interface or conventional gait rehabilitation for 20 minutes x 20 sessions. Outcome measures were functional ambulation Category (FAC), gait speed, gait endurance and lower muscle strength. Measures were taken at baseline and 1, 2, 3 and 4 weeks. The GTLI group significantly improved gait speed and gait endurance compared with the control group. However, FAC and lower limb muscle strength were not significantly different. The results suggest that gait rehabilitation using the footpad-type locomotion interface can improve gait ability better than conventional gait rehabilitation.

Development of a Novel Omnidirectional Treadmill-Based Locomotion Interface Device with Running Capability

To achieve an immersive virtual reality (VR) environment, omnidirectional treadmills (ODTs) allow users to perform locomotion in any direction. However, existing ODTs are heavy and complex, and operate at low speeds. This limits fast user motion and prevents natural interactions in real applications such as military training programs and interactive games. In this paper, we introduce a novel locomotion interface device with running capability, which uses an omnidirectional treadmill with a new power transmission mechanism and a locomotion controller that enables the user to make fast movements. As a result of the improved power transmission performance due to the simple and relatively lightweight structure, the proposed two-dimensional treadmill can generate a maximum speed of 3 m/s, with an acceleration of 3 m/s2. Moreover, through a pilot test with the proposed locomotion interface device, we verified that the fast directional changes during walking and running with the designed speed adaptation controller do not exceed the acceleration performance of the proposed system. Due to its wide range of movement speeds and acceleration capabilities, and lack of any motion constraints, the proposed locomotion interface device with a novel ODT can be used as a representative platform in various VR environments to enhance the immersive experience.

Sensory conflict alters visual perception of action capabilities during crossing of a closing gap in virtual reality.

The somatosensory, vestibular, and visual systems contribute to multisensory integration, which facilitates locomotion around obstacles in the environment. The joystick-controlled virtual reality (VR) locomotion interface does not preserve congruent sensory input like real-walking, yet is commonly used in human behaviour research. Our purpose was to determine if collision avoidance behaviours were affected during an aperture crossing task when somatosensory and vestibular input were incongruent, and only vision was accurate. Participants included 36 young adults who completed a closing gap aperture crossing task in VR using real-walking and joystick-controlled locomotion. Participants successfully completed the task using both interfaces. Switch point between passable and impassable apertures was larger for joystick-controlled locomotion compared with real-walking, but time-to-contact (TTC) was lower for real-walking than joystick-controlled locomotion. Increased joystick-controlled locomotion switch point may be attributed to incongruency between visual and non-visual information, causing underestimation of distance travelled towards the aperture. Performance on future VR applications incorporating dynamically changing gaps can be considered successful using joystick-controlled locomotion, while taking into account a potential behaviour difference. Differences in TTC may be explained by the requirement of gait termination in real-walking but not in joystick-controlled locomotion. Future VR studies would benefit from programming acceleration and deceleration into joystick-controlled locomotion interfaces.

A Study on Locomotion Interface That Can Present Foot and Arm Movements Simultaneously

A Study on Locomotion Interface That Can Present Foot and Arm Movements Simultaneously

The Treadport: Natural Gait on a Treadmill

To evaluate the differences between walking on an advanced robotic locomotion interface called the Treadport and walking overground with healthy subjects. Previous studies have compared treadmill-based and overground walking in terms of gait parameters. The Treadport's unique features including self-selected speed capability, large belt, kinesthetic force feedback, and virtual reality environment distinguish it from other locomotion interfaces and could provide a natural walking experience for the users. Young, healthy subjects (N = 17) walked 10 meters 10 times each for both overground and the Treadport environments. Comparison between walking conditions used spatiotemporal and kinematic parameters. In addition, electromyographic data was collected for five of the 17 subjects to compare muscle activity between the two conditions. Gait on the Treadport was found to have no significant differences (p > .05) with overground walking in terms of hip and knee joint angles, cadence and stride length and stride speed, and muscle activation of the four muscle groups measured. Differences (p < .05) were observed in ankle dorsiflexion which was reduced by 2.47 ± 0.01 degrees on the Treadport. Walking overground and on the Treadport is highly correlated and not significantly different in 13 of 14 parameters. This study suggests that the Treadport creates an environment for natural walking experience, where natural gait of users is almost preserved, with great potential to be useful for other applications, such as gait rehabilitation of individuals with walking impairments.

Geospatial Google Street View with Virtual Reality: A Motivational Approach for Spatial Training Education

Motivation is a determining factor in the learning process, and encourages the student to participate in activities that increase their performance. Learning strategies supplemented by computer technology in a scenario-based learning environment can improve students′ motivation for spatial knowledge acquisition. In this sense, a workshop carried out with 43-second year engineering students supported by Google Street View mobile geospatial application for location-based tasks is presented, in which participants work in an immersive wayfinding 3D urban environment on virtual reality. Students use their own smartphones with Google Street View application integrated in virtual reality (VR) 3D glasses with a joystick as locomotion interface. The tool to analyse the motivational factor of this pedagogical approach is the multidimensional measurement device Intrinsic Motivation Inventory with six subscales: interest, perceived competence, perceived choice, effort, tension, and value, measured on a seven point Likert scale. Scores in all subscales considered are above 4 on a scale of 7. A usability study conducted at the end of the experiment provides values above 3 on a scale of 5 in efficacy, efficiency and satisfaction. The results of the experiment carried out indicate that geospatial Google Street View application in Virtual Reality is a motivating educational purpose in the field of spatial training.

「ロコモーションインタフェース」特集号について( ロコモーションインタフェース)

「ロコモーションインタフェース」特集号について( ロコモーションインタフェース)

足踏式空間移動インタフェース(WARP)の開発と評価

足踏式空間移動インタフェース(WARP)の開発と評価

Efficacy of the Gait Training Using Footpad-Type Locomotion Interface in Chronic Post-Stroke Patients: A Pilot Study

Purpose: In recent years, robotics have been used for rehabilitation. We developed a footpad-type locomotion interface using robot technology, and we reported improvement on gait speed and muscle strength. The purpose of this study was to compare the effects of gait training using a footpad-type locomotion interface (GTLI) with those of body weight support treadmill training (BWSTT). Methods: Eleven chronic post-stroke patients participated in this study. The subjects received GTLI and BWSTT respectively three times a week for a total of 12 times. The outcome measures were maximum gait speed, timed up and go test, and isometric muscle strengths of both hip and knee flexion and extension Result: No differences were observed in the gait speed and timed up and go test among GTLI and BWSTT. In isometric muscle strengths, GTLI improved better than BWSTT. Conclusion: These results suggest that GTLI and BWST have similar effects on improving the gait and balance abilities. In addition, GTLI is more effective in improving the isometric muscle strength of hip extension and knee flexion than using BWSTT.