arXiv subjects

Hiroyasu Iwata

Publications and source records attributed to Hiroyasu Iwata.

3 recordsLinked to original sources

arXiv2026

MESSPa: A Multi-modal Embodiment Stimulation Shoulder Pad for Preserving the Sense of Agency in a Detachable Robotic Arm

Wearable robots such as supernumerary robotic limbs (SRLs) can augment human capability, but their effectiveness depends strongly on the operator's sense of embodiment, comprising the sense of agency (SoA) and the sense of ownership (SoO). When an SRL is detached from the body so that the operator can act in two places at once, both the sense of agency and task performance tend to degrade. This paper presents the Multi-modal Embodiment Stimulation Shoulder Pad (MESSPa), a wearable interface that combines one-to-one motion transfer with spatially distributed pneumatic (balloon) haptic feedback on the shoulder, with the goal of preserving the sense of agency across attached and detached states. We describe the system design, the control mapping, and a controlled experiment using a $2\times2$ mixed design that crosses the control interface between groups (MESSPa, $N=13$, vs. keyboard control, $N=12$ from our previous study) and attachment (on-shoulder/detached) within participants, under single- and dual-task loads. Compared with keyboard control in the detached condition, MESSPa significantly reduced task completion time and significantly improved the sense of agency in the detached state, while narrowing the performance gap between the attached and detached conditions. The sense of ownership did not change significantly. These results indicate that combining motion transfer with positional haptic feedback is an effective way to recover agency when a robotic limb is operated remotely.

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arXiv2026

Hybrid Roller-Jamming Gripper for Object Acquisition and Retention Under Pose Uncertainty

In household manipulation, pose uncertainty often results in off-centre or partial initial contact, making reliable object acquisition difficult. Roller-based grippers can actively draw objects inward but often provide limited post-capture stability, whereas granular-jamming grippers require sufficient contact before jamming to achieve strong retention. This paper presents a hybrid roller-jamming gripper that integrates active object intake and post-capture retention within a single gripper. The proposed gripper uses inward roller rotation to increase contact and draw the object toward the gripper centre, followed by vacuum-induced granular jamming to stiffen the rollers and stabilise the grasp. The paper also presents a simplified geometric analysis of the gripper and a bench-level characterisation of the prototype's force capability. The gripper prototype was mounted on a 7-DoF robotic arm and evaluated using eight test objects. Furthermore, controlled planar position and orientation offsets were applied, with each condition repeated three times. The main evaluation comprised 840 grasp trials, including 216 planar-offset trials and 624 orientation-offset trials. Overall, the gripper succeeded in 812/840 trials: 215/216 planar-offset trials and 597/624 orientation-offset trials. The ablation evaluation comprised 162 trials on three objects. The roller-only and jamming-only conditions achieved 54/81 and 24/81 successes, respectively, showing their different contributions. These results provide initial mechanism-level evidence that hybrid roller-jamming is a promising strategy for improving acquisition and retention after imperfect first contact.

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arXiv2022

Diagnostic Posture Control System for Seated-Style Echocardiography Robot

Purpose: Conventional robotic ultrasound systems were utilized with patients in supine positions. Meanwhile, the limitation of the systems is that it is difficult to evacuate the patients in case of emergency (e.g., patient discomfort and system failure) because the patients are restricted between the robot system and bed. Then, it is ideal that the patient undergoes the examination in the sitting position in terms of safety. Therefore, we validated a feasibility study of seated-style echocardiography using a robot. Method: Preliminary experiments were conducted to verify the following two points: (1) the possibility of obtaining cardiac disease features in the sitting posture as well as in the conventional examination, and (2) the relationship between posture angle and physical burden. For reducing the physical burden, two unique mechanisms were incorporated into the system: (1) a leg pendulum base mechanism to reduce the load on the legs when the lateral bending angle increases, and (2) a roll angle division by a lumbar lateral bending and thoracic rotation mechanisms. Results: Preliminary results demonstrated that adjusting the diagnostic posture angle enabled us to obtain the views, including cardiac disease features, as in the conventional examination. The results showed that the body burden increased as the posture's lateral bending angle increased. The results also demonstrated that the body load reduction mechanism incorporated in the results could reduce the physical load in the seated echocardiography. Conclusion: These results showed the potential of the seated-style echocardiography robot.

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