Sensorized, Flat, Pneumatic Artificial Muscle Embedded with Biomimetic Microfluidic Sensors for Proprioceptive Feedback

Abstract

In recent years, soft components, such as pneumatic artificial muscles (PAMs), have been increasingly employed to design safer wearable devices. Despite the inherent compliance of the materials used to fabricate PAMs, the actuators are able to produce relatively large forces and work when compared to their weight. However, effective operation of these systems has traditionally required bulky external force and position sensors, which limit the maneuverability of users. To overcome these issues, inspiration was taken from organic muscles, which incorporate embedded sensors, such as Golgi tendon organs and muscle spindles, to provide real-time position and force feedback for muscles. As such, a sensorized, flat, pneumatic artificial muscle (sFPAM) with embedded force and position sensors was designed and fabricated. In addition, a hyperelastic model was developed and verified through comparison with the experimentally characterized mechanical and electrical performance of the sFPAM. Furthermore, a sliding mode controller was implemented to demonstrate the feasibility of embedded sensors to provide feedback during operation. Ultimately, a lightweight, compact actuation system was designed with the ability to be seamlessly incorporated into future wearable devices.

Electronic skins and machine learning for intelligent soft robots

“…The use of soft tactile sensors for closed-loop control is still in its nascency. The few relevant studies in this area use low-dimensional soft strain sensors for closed-loop kinematic or force control (76,120,121). This is surprising given the wealth of literature on soft sensing technologies and considering the intended application of these sensors (32).…”

Advances in Liquid Metal-Enabled Flexible and Wearable Sensors

“…Pneumatic artificial muscles have been increasingly investigated owing to the potential in wearable devices. Inspired by biological muscle, Jackson et al designed an artificial muscle with both force and position sensors [137], as shown in Figure 11A. The Golgi tendon organ and muscle spindle were fabricated by EGaIn.…”

“…[136]. (B) The sensorized, flat, pneumatic artificial muscle at rest and inflated to 82.8 kPa, reproduced with permission from [137]. (C) Illustration of the contraction and pressure sensors, reproduced with permission from [137].…”

“…(B) The sensorized, flat, pneumatic artificial muscle at rest and inflated to 82.8 kPa, reproduced with permission from [137]. (C) Illustration of the contraction and pressure sensors, reproduced with permission from [137]. (D) The electrical environment of a liquid-metal microsphere in NaOH solution (above) and two methods of communicating for liquid-metal microspheres in a circuit (below), reproduced with permission from [77].…”

Hybrid System Analysis and Control of a Soft Robotic Gripper with Embedded Proprioceptive Sensing for Enhanced Gripping Performance

“…[30][31][32][33] In this study, by taking advantage of the deformable feature of the soft robot, we estimate the high-dimensional but coupled states of the system using a single embedded proprioceptive soft sensor. [34][35][36][37] The concept of proprioception comes from biological muscle systems, where a muscular unit internally detects its stretch or stress by the embedded sensing elements inside, such as muscle spindles or Golgi tendon organs. [38,39] We first understand how the deformations (outputs) are distributed along the finger according to the state and then we suggest the estimation strategy based on the mapping from the state to the outputs.…”