cs.HCAug 20, 2026

Pneumatic Units for Logic-based Sequential Excitation (PULSE) in Wearable Haptic Devices

Authors: Jessica Healey, Anoush Sepehri, Michael T. Tolley, Tania K. Morimoto

Organizations: University of California, San Diego, La Jolla CA 92093, USA

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Abstract

Soft, wearable robotic devices can deliver haptic feedback to support a wide range of tasks, such as extended reality, training various skills, and rehabilitation. Pneumatic actuation can deliver complex haptic feedback, is lightweight and compliant, and can be incorporated into textiles, making it promising for wearable applications. These soft pneumatic devices, however, typically require a valve and input for each pneumatic actuator, making it challenging to develop fully portable devices for at-home use. In this work we present a pneumatic unit for logic-based sequential excitation (PULSE). The PULSE is a flat, textile-based pneumatic actuator with embedded fluidic logic. By combining these actuators into a fluidic ring oscillator, we decreased the typical amount of required pneumatic inputs for a haptic forearm sleeve by 60%, with the ability to scale. We built the ring oscillator by optimizing design variables to reach desired periods of oscillation. We demonstrated a set of tactile stroking cues with periods ranging from 1.16 to 1.56 s and forces ranging from 1.07 to 2.04 N. We assessed the sleeve's ability to render differentiable, pleasant, and continuous haptic cues in a user study. The forearm sleeve containing PULSEs successfully delivered four directional cues and guided users to target wrist angles with fast reaction times, low overshoot amounts, and a 93.3% average accuracy of correct initial directions.

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Fig. 1: Overview of the wearable haptic sleeve containing PULSEs. The PULSE operates as an inverter and is shown in its (a) deflated and (b) inflated states. (c) With combined logic and actuation in one unit, the PULSE can be easily integrated into a haptic forearm sleeve and deliver sequential tactile cues to users. The top image is a schematic of the PULSE in a pneumatic ring oscillator, the middle image is a representation of the pressure response of the PULSEs, and the bottom image is a representation of the stroking sensation a user will experience, where the intensity of the color shown relates to the intensity of the PULSE’s normal force on the skin.
Fig. 2: Ring oscillator schematics and their pressure profiles. (a) Schematic of a ring oscillator with three PULSEs and its pressure profile. RtR_{t} denotes resistance of the tubing between each actuator and RpdR_{pd} denotes resistance of the pulldown resistor. (b) Schematic of a ring oscillator with five PULSEs and the ability to change direction of oscillation. RtR_{t} and RpdR_{pd} are unlabeled but reside in the same places as in (a). The tubes connecting each actuator pass through the ‘switch’ actuators at the top of the image before connecting to the input of the next actuator. (c) The pressure profiles for five PULSEs able to change direction.
Fig. 3: Fabrication of the PULSE and haptic sleeve. (a) To fabricate the PULSE, we heat-pressed the fabric layers together with the PET layer in between. We then sealed heat-shrink around the tubing and indented it to align with the center of the heat-sealed section (where the fold will occur upon inflation). We glued this tubing on top of the fabric layers. (b) Deflated and inflated states of the actuator. (c) The effect of different cutout angles on the PULSE’s buckling pressure. Error bars represent the standard deviations of the buckling pressure from three different measurements. (d) The fabrication process of the haptic sleeve. (e) PULSEs were inserted into the sleeve and tubing was connected externally.
Fig. 4: Comparisons between the experimental data of the ring oscillator using the PULSEs and the model. Comparisons shown for (a) the number of actuators, (b) the length of the pulldown resistors, and (c) the diameter of the actuators. Case A in (b) refers to a version of the predictive model without accounting for an additional resistance term in the pulldown resistance, and Case B includes this resistance term. Error bars in (a) and (b) represent the standard deviations of the oscillation period from three different measurements and three different sets of actuators. Error bars in (c) represent the standard deviations of the oscillation period from three different measurements.
Fig. 5: Characterization of the final sleeve. (a) The predicted oscillation period based on the optimization and experimental data from the final sleeve. (b) Force of an individual PULSE within a ring oscillator over supply pressures. The y-axis is the difference between the maximum force measured from the PULSE and the preload force measured from tightening the sleeve. Error bars in both plots represent the standard deviations from three measurements.
Fig. 6: Results for the user study. (a) Image of the test set up and rendered haptic cues, with the participant’s vision and hearing blocked and their arm resting on the elbow and wrist supports. (b) Total cue identification results presented as percentages in a confusion matrix. (c) Box plots show the pleasantness and continuity rankings of the High and Low cues on a 5-point Likert scale. (d) Depiction of angle guidance task with representative results from one participant. (e) Box plots show the reaction time, settling time, maximum overshoot, and fraction of wrong initial directions for reaching target angles.
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