High‐performance artificial muscle is always the pursuit of researchers for robotics. Herein, a bionic artificial muscle is reported called “ExoMuscle” mimicking the sarcomere in skeletal muscle with a bio‐inspired structure to contract “myofilaments” enabling the artificial muscle to mimic the architecture of muscle such as parallel, fusiform, convergent, and pennation and beyond the performance of skeletal muscle. The reported actuators excel in various aspects compared with skeletal muscle including actuation stress (0.41–0.9 MPa), strain (50%), optimal length, velocity‐independence output, power density (10.94 kW kg⁻¹), and efficiency (69.11%). With its own adjustable pennation architecture, it achieves variable actuation stress up to 0.9 MPa meanwhile maintaining high efficiency. Furthermore, ExoMuscle highly conforms to the anatomical complexity of the human body to cooperate with skeletal muscles closely opening the door for bio‐robotics, especially wearable robots.

This letter presents a pneumatic artificial muscle-based elbow exosuit designed for driving and assisting the elbow joint. By combining the bionic attachment method inspired by the brachioradialis muscle and the pennation architecture of the artificial muscle, the elbow exosuit achieves high output torque while maintaining a slim profile of only 10 mm thickness. To guide the design process, the letter utilizes the force balance condition of infinitesimal parts of the artificial muscle fiber and the virtual work principle to calculate the path change of the muscle wrapped around the arm surface. This approach helps determine key parameters and obtain the theoretical assisting torque. To validate the model, a test bench is constructed to measure the relationship between assisting torque and flexion angle, demonstrating the accuracy of the theoretical calculations. Furthermore, a bionic elbow joint is built to verify the driving ability of the exosuit. Preliminary human feasibility test is conducted, and users report no discomfort. The results indicate a 37.5% decrease in muscle effort in the bicep brachii when lifting a 4 kg weight and a 30.5% decrease during the holding task. A stroke survivor successfully bends the arm and raises his hand to the mouth while wearing the exosuit. These findings demonstrate the feasibility in driving and providing assistance to the user and significant potential for assisting individuals in their daily lives.

This paper presents a novel flat modular pneumatic artificial muscle (FMPAM) consisting of thin-film cylinder modules, which have no expansion in the thickness direction when pressurized to generate transverse force, and transverse-to-longitudinal deformation translation structures around modules, which accumulate the distributional deformation and ultimately obtain large cumulative deformation and output force. The FMPAM is designed for contractile assistance in soft wearable robots to achieve no squeezing on users’ skin and better wearing comfort. This design combines the advantage of fast time response of positive-pressure pneumatic artificial muscles (PAMs) and the features of good flexibility of negative-pressure ones. Additionally, the design avoids the disadvantages of relatively large thickness or radical expansion of positive-pressure PAMs. In this paper, the design and processing methods of the FMPAM are introduced in detail. It is worth mentioning that the whole FMPAM is printed utilizing the same type of material at one time. Identification of the module model is carried out. Module net output force and restoring force test benches are built to acquire experimental data for assisting the modeling. The shape of the film and modular output force can be predicted during actuation. Experimental results show that low predictive error can be obtained. Finally, an output force test bench, various radius arches and an arm-like structure are built to verify the output characteristics of the FMPAM: good compliance to surfaces with different radiuses, long-lasting endurance (more than 10 000 reciprocating cycles), and high response speed (100 Hz), indicating that the proposed design can provide theoretical guidance and a good alternative for soft wearable robot actuators.

This paper proposes a pneumatic artificial muscle based on a novel winding method. By this method, the inflation of silicone tubes is transformed to the contraction of muscle, whereas the expansion keeps on one side of the muscle, i.e., the expansion of the actuator does not affect the object close to it. Hence the muscle is great for wearable robots without squeezing on the user’s skin. Through necessary simplification, the contraction ratio model and force model are proposed and verified by experiments. The prototype of this paper has a maximum contraction ratio of 35.8% and a maximum output force of 12.24 N with only 5 mm thickness. The high compatibility proves it excellent to be the alternative for wearable robots.

This study proposes a novel artificial muscle based on a pouch-type actuator with a contraction ratio amplification mechanism (CRAM). The CRAM places the final length of the pouch-type actuator into a secondary direction, while the main direction is used only for contraction purpose. Thus, the contraction ratio is substantially increased. The interaction process model between the pouch-type actuator and the mechanism is developed through the principle of virtual work, allowing us to select the adequate parameters so that the contraction ratio of the pouch-type actuator improves up to 48.3%. This improvement is 1.372 times that of the original pouch-type actuator. The output characterization is tested to verify the virtual work model of the process. Moreover, a capacitance-based displacement sensor with low root-mean-square error is built and placed in the actuator. The sensor does not increase the complexity of the system and has high repeatability and linearity. The overall functionality of the sensor is verified through sinusoidal and square-wave tracking experiments employing closed-loop control. Finally, a preliminary upper-limb-assisting test verifies that the actuator can reduce 17.48% of the muscle effort. In sum, this artificial muscle with good performance provides a design reference and alternative for wearable applications.

Artificial muscles have been in development for decades and play a crucial role in the field of wearable robotics. However, a universal device for both sensing and regulating forces in artificial muscles is still absent, rendering scenario-required force control unfeasible. Inspired by Golgi tendon organs, this work proposes bionic ExoTendon for force sensing and regulating in artificial muscles as a general solution. Leveraging the principles of triboelectrification and electrostatic induction, the ExoTendon offers high linearity, minimal hysteresis, and adjustable sensitivity and range, making it suitable as the tendon of artificial muscles. Specifically, the ExoTendon effectively enable adjustment to the pretension of the artificial muscles, yielding various assistive forces under the same input. With the optimized pretension level and closed-loop force control, the artificial muscle–based exosuit achieves self–force regulation, substantially improving walking balance and speed in stroke subjects under low input, demonstrating its promise in wearable robotics and rehabilitation medicine.