This paper introduces a quadruped soft-amphibious robot using 4.0 mm diameter thin and soft McKibben actuator. The robot utilizes its leg and body bending mechanism to locomote. For each leg, three links of the actuators are arranged in parallel with fixed upper and bottom part. Then, four actuators are arranged in parallel and fixed with a thin plastic plate in between the actuators for the body motion. The elastic deformation of the plastic plate actuated by the actuators assist in the side-to-side motion of the robot mimicking the gait of the biological creature like lizard/salamander during walking motion. FEM simulation studies were performed in Marc Mentat® to evaluate the bending behaviors and validated with an experimental test. Walking experiment was tested on a flat surface and on sand using two different gaits of trot and crawl gait. On the other hand, swimming experiment was tested inside water using only crawl gait. Different input pressure and frequency were varied to study the walking behavior. The robot successfully walks on a flat and 10 o incline plane with a maximum speed of 0.056 m/s using trot gait and robust to move on sand and in water using the crawl gait at 0.041 m/s and 0.022 m/s, respectively.
Over recent years, the reseach in the field of soft actuation has been extensively increased for achieving more complex motion path with smooth, high flexible movement and high generated force at minimum operating pressure. This paper presents the study on gripping force capability of soft actuators applied on glove-type finger exoskeleton, developed in motivation to assist individuals having weak finger gripping ability in their rehabilitation exercise towards hand function restoration. The exoskeleton utilizes five cylindrical shaped pneumatic bending actuators developed in the lab, which use fiber reinforcement as a cause of bending motion that drive finger’s flexion movement. Four right-handed healthy volunteers simulated paralysis participated in the study. At 200kPa safe operating pressure, the soft exoskeleton worn by the subjects demonstrates the ability to provide adequate grip force. The grip force generated from exoskeleton worn on passive right hand is 4.66 ± 0.2 N and 3.61± 0.2 N from passive left hand, both higher than the minimum grip forces measured to hold the Hand Dynamometer of 240 g. It shows good potential to be used as a finger rehabilitation assist device.
Technological advancement has made rehabilitation robotics possible. Robots can now help patients to proceed with their physiotherapy treatment with less assistance from physiotherapists. Soft robots are made from material similar to living organisms to improve safety between human and robot interaction. A soft robotic foot exoskeleton using pneumatic fiber braided bending-type actuator was developed in this study. Focusing on dorsiflexion ankle stretching movement, several actuator positioning was performed to gain the maximum ankle angle. MPU6050 sensor was used to detect the ankle dorsiflexion angle. Without any load, the bending-type actuator was able to bend and meet end-to-end of the tip. ITV0031-2ML valve was used as the connecter between air pressure supply and electronic circuit. Several experimental setups have been used in this study to obtain the maximum ankle dorsiflexion angle. The average maximum dorsiflexion angle from healthy volunteers was 8-degree, and Phase II experimental setup was able to drive a maximum of 6-degree dorsiflexion angle.
Over recent years, studies on soft mechanism are rapidly being paid to attention especially in pneumatic actuator field. Good actuator should be able to provide sufficient force and flexibility in movement, hence bending motion is vital criteria needed in soft robotic actuation. In this paper, a solution to soft bending pneumatic actuator is proposed in which several patterns fiber weave designs are introduced. The objectives of the simulations is to investigate which weave patterns combination of fiber reinforced actuator models yields the best bending characteristics and its relation to the contraction or extension characteristics shown by single weave pattern actuator models. From the results, when two patterns of fiber weave are attached together to form a sleeve, significant bending were obtained from most of the models simulated. Large bending resulted from combined two patterns fiber weave models are achieved when maximum contraction and extension characteristics exhibit by both fiber weave patterns.
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