Biomechanics: Hydroskeletal

doi:10.1016/B978-008045046-9.01948-3

Encyclopedia of Neuroscience

2009, Pages 189-200

https://doi.org/10.1016/B978-008045046-9.01948-3 Get rights and content

Many animals lack hard skeletons and create their skeletal systems using muscles and the incompressibility of fluid. Some have a fluid-filled cavity surrounded by muscles and connective tissue, whereas others, termed muscular hydrostats, lack such cavity and are mainly composed of a tightly packed array of muscles. The arrangement of muscle fibers in different orientations combined with sensory and control systems enables complex and diverse movements without any rigid element. The interaction of biomechanics and control in hydrostatic skeletons is discussed using three examples: octopus arm movements, tongue protrusion in frogs, and whole-body movements in the leech.

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Cited by (15)

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This study presents an innovative approach in soft robotics, focusing on an inchworm-inspired robot designed for enhanced transport capabilities. We explore the impact of various parameters on the robot’s performance, including the number of activated sections, object size and material, supplied air pressure, and command execution rate. Through a series of controlled experiments, we demonstrate that the robot can achieve a maximum transportation speed of 8.54 mm/s and handle loads exceeding 100 g, significantly outperforming existing models in both speed and load capacity. Our findings provide valuable insights into the optimization of soft robotic design for improved efficiency and adaptability in transport tasks. This research not only contributes to the advancement of soft robotics but also opens new avenues for practical applications in areas requiring precise and efficient object manipulation. The study underscores the potential of biomimetic designs in robotics and sets a new benchmark for future developments in the field.
Peristaltic transporting device inspired by large intestine structure
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A pneumatic large intestine-like soft robot with McKibben muscles is designed based on traveling wave motion. The robot consists of four sections, and each section is controlled by axial and circular muscles independently. The robot can propagate traveling waves inspired by the large intestine’s peristaltic wave, defined by the wavelength and delay of the axial and circular muscles’ supplied air signals. This motion can transport the object in the inner cavity of the robot, making the maximum Transport Capacity Index of 0.069 (with an actual speed of 0.77 mm/s). This study investigates the effect of different parameters of traveling waves generated by axial and circular muscles independently on the ability of a robot to transport the object. Various combinations of traveling waves will lead to different transport directions and speeds of the object and provide more possibilities for selecting control patterns. Furthermore, the proposed robot not only demonstrates effective transportation capabilities for solid objects, but it also has the capacity to transport soft objects. This study can provide new ideas for animal tubular organ bioinspired device design and prototype design references for medical teaching tools.
Sensorized objects used to quantitatively study distal grasping in the African elephant
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Nature evolved many ways to grasp objects without using hands: elephants, octopuses, and monkeys use highly dexterous appendices. From a roboticist’s perspective, the elephant trunk is a fascinating manipulator, which strategies can empower robots’ interaction capabilities. However, quantifying prehensile forces in such large animals in a safe, ethical, and reproducible manner is challenging. We developed two sensorized objects to investigate the grasping of an adult African elephant with deliberately occluded vision. A cylinder and a handle provided a distributed force (80 and 6 taxels) and inertial measurements in real-time, resisting dirt and shocks. The animal curled the distal portion of the trunk to grasp the tools. Using force and contact area data of the cylinder revealed the animal’s ability to finely modulate pressure. The handle data provided insights into the energy-efficient behavior of the animal, with no significant grasping force changes despite variations imposed on both weight (5-15 kg) and initial position of the object.
Measuring the force of the tip of the elephants trunk
2022, MethodsX
Citation Excerpt :
For example, they focused on bite force (e.g. on carnivorous [1], on insectivorous [2], on lizards [3] but also on pulling or pinching force with no endoskeleton system (e.g. on arthropods coconut crabs claws [4] or octopus arms [5]. The elephant's trunk is at the center of many fields of research, from evolutionary biology [6] to biomechanics [7] or soft robotics [8]. It is a multitask organ capable of combining high precision in the distal part and high power in its entirety and performing many tasks in a large working space.
Forces that animals can exert is of great interest in biology. Regarding the elephant trunk, the maximum mass that an elephant can lift with its trunk is known, but the pinching force of the trunk tip is unknown. We here present an original system to measure this force for an organ much coveted in soft robotics for example.
It consists of:
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  A wooden box protecting the elephants and the measuring system with no protruding parts except the sensor. This box has an opening at the back to fill it with apples and a trap door at the front to release the apples.
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  Two load cells protruding from the box connected to an electronic system controlled by an Arduino card that records and sends the pinch force via Wi-Fi to a laptop while releasing a reward apple.
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  Depending on the threshold chosen, the elephant must pinch harder than the previous time to release the next apple. The repetition of this action allows us to approach the maximum force it can achieve.
The system, tested on elephants at the Beauval Zooparc (France), has demonstrated that it is effective in measuring the pinching force of the tip of the trunk.
A Year at the Forefront of Hydrostat Motion
2023, Biology Open
Currently, in the field of interdisciplinary work in biology, there has been a significant push by the soft robotic community to understand the motion and maneuverability of hydrostats. This Review seeks to expand the muscular hydrostat hypothesis toward new structures, including plants, and introduce innovative techniques to the hydrostat community on new modeling, simulating, mimicking, and observing hydrostat motion methods. These methods range from ideas of kirigami, origami, and knitting for mimic creation to utilizing reinforcement learning for control of bio-inspired soft robotic systems. It is now being understood through modeling that different mechanisms can inhibit traditional hydrostat motion, such as skin, nostrils, or sheathed layered muscle walls. The impact of this Review will highlight these mechanisms, including asymmetries, and discuss the critical next steps toward understanding their motion and how species with hydrostat structures control such complex motions, highlighting work from January 2022 to December 2022.
Kinematic model to control the end-effector of a continuum robot for multi-axis processing
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