The Design, Kinematics and Torque Analysis of the Self-Bending Soft Contraction Actuator

Abstract

This article presents the development of a self-bending contraction actuator (SBCA) through the analysis of its structure, kinematics, and torque formulas, and then explores its applications. The proposed actuator has been fabricated by two methods to prove the efficiency of the human body inspiration, which represents the covering of human bones by soft tissues to protect the bone and give the soft texture. The SBCA provides bending behaviour along with a high force-to-weight ratio. As with the simple pneumatic muscle actuator (PMA), the SBCA is soft and easy to implement. Both the kinematics and the torque formula presented for the SBCA are scalable and can be used with different actuator sizes. The bending actuator has been tested under an air pressure of up to 500 kPa, and the behaviour of its bending angle, parameters, dimensions, and the bending torques have been illustrated. On the other hand, the experiments showed the efficient performances of the actuator and validate the proposed kinematics. Therefore, the actuator can be used in many different applications, such as soft grippers and continuum arms.

Design, Implementation, and Kinematics of a Twisting Robot Continuum Arm Inspired by Human Forearm Movements

“…A similar effect is given when using extensor PMAs to build an extension soft arm to provide the ability for extension and bending [19]. Another design has been presented by the authors for a bending arm that uses a single self-bending contraction actuator (SBCA) [20]. On the other hand, a twisting copper wire is inserted into a soft body to provide a bending behaviour and twisting behaviour by using the wire itself [21].…”

“…According to its design, the pneumatic air muscle shows linear behaviour such as contraction and extension. An innovative design of contraction PMA is presented by [33] which provides a mechanical design that allows the muscle slides on a shaft and shows 30% more tensile force than the traditional contraction PMA Furthermore, the modified actuators offer bending and diameter reduction behaviour [20,34,35] Though, the air muscle does not have the capability to twist itself.…”

Controlling of Pneumatic Muscle Actuator Systems by Parallel Structure of Neural Network and Proportional Controllers (PNNP)

“…The presented SBCA in Al-Ibadi et al (2020) has been used in this section to control its bending angle. The specifications of the bending actuator are listed in Table 1. FIGURE 7 | The unit step response of the length controller system at 0.5 Hz.…”

“…Soft robotics represents a new generation of robotic research, which provides numerous advantages, such as being lightweight, safe for close contact with humans, and environmentally friendly, as well as having low cost in terms of materials, construction time, and power (Neppalli and Jones, 2007 ; Trivedi et al, 2008 ; Al-Ibadi et al, 2020 ). In addition to the general advantages of soft robotics, soft actuators, such as contraction and extension pneumatic muscle actuators (PMAs), have their benefits when compared with the traditional electrical and mechanical actuators.…”

Design and optimization of actuator for multi-joint soft rehabilitation glove

“…But the structure of a continuous sinusoidal-shaped channel inside the actuator is complex and the actuator needs a long fabrication period. Al-Ibadi et al (2017) and Al-Fahaam et al (2017) developed a pneumatic muscle actuator by extending McKibben artificial muscles. The actuator has high elastic properties and can achieve a bending angle of up to 500°.…”