8.8 Soft robotics

Soft robotics is revolutionizing the field by using flexible materials to create adaptable, safe robots. These robots can interact with humans and navigate complex environments, offering advantages in adaptability, safety, and delicate task performance.

Challenges in soft robotics include control, actuation, and durability. Researchers are developing new strategies and materials to address these issues. Applications range from biomedical devices to exploration, with future trends focusing on smart materials and biohybrid robots.

Soft materials in robotics

• Soft materials are increasingly being used in robotics to create more adaptable, flexible, and safe robots that can interact with humans and navigate complex environments
• Soft materials include elastomers, hydrogels, and other compliant materials that can deform and conform to their surroundings
• The use of soft materials in robotics is inspired by biological systems, which often rely on soft tissues and structures to achieve complex movements and functions

Advantages of soft robotics

• Soft robots offer several advantages over traditional rigid robots, including increased adaptability, safety, and the ability to perform delicate tasks
• The use of soft materials allows robots to conform to their environment and interact with objects of various shapes and sizes

Adaptability and flexibility

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Top images from around the web for Adaptability and flexibility

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  Frontiers | Modeling of Deformable Objects for Robotic Manipulation: A Tutorial and Review View original

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  Frontiers | CLASH—A Compliant Sensorized Hand for Handling Delicate Objects View original

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  Frontiers | AQuRo: A Cat-like Adaptive Quadruped Robot With Novel Bio-Inspired Capabilities View original

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• Soft robots can deform and adapt to their surroundings, enabling them to navigate through confined spaces and handle delicate objects
• The flexibility of soft materials allows robots to perform complex movements and adapt to changing environments
• Examples of adaptable soft robots include snake-like robots that can navigate through narrow passages and soft grippers that can handle fragile objects (fruits, eggs)

Safety in human interaction

• Soft robots are inherently safer than rigid robots when interacting with humans due to their compliant nature
• The use of soft materials reduces the risk of injury in case of collisions or unintended contact
• Soft robots can be used in applications where human-robot interaction is necessary, such as in assistive devices and collaborative robots (exoskeletons, rehabilitation robots)

Challenges of soft robotics

• Despite the advantages of soft robotics, there are several challenges that need to be addressed to enable their widespread adoption
• These challenges include the control and actuation of soft robots, as well as their durability and robustness

Control and actuation

• Controlling soft robots is more challenging than controlling rigid robots due to their inherent compliance and nonlinear behavior
• Traditional control methods used in rigid robotics may not be directly applicable to soft robots
• Researchers are developing new control strategies and algorithms specifically tailored for soft robots, such as model-based control and learning-based control (reinforcement learning, neural networks)

Durability and robustness

• Soft materials used in robotics are often less durable than rigid materials, which can limit their lifetime and performance
• Soft robots are more susceptible to wear and tear, punctures, and other forms of damage
• Researchers are exploring new materials and fabrication techniques to improve the durability and robustness of soft robots, such as self-healing materials and reinforced composites

Soft actuators and sensors

• Soft actuators and sensors are essential components of soft robots, enabling them to generate motion and sense their environment
• Various types of soft actuators and sensors have been developed, each with their own advantages and limitations

Pneumatic actuators

• Pneumatic actuators use compressed air to generate motion and force
• They are widely used in soft robotics due to their simplicity, low cost, and high power-to-weight ratio
• Examples of pneumatic actuators include McKibben muscles, PneuNets, and soft bellows actuators

Hydraulic actuators

• Hydraulic actuators use pressurized fluids, such as water or oil, to generate motion and force
• They offer high force output and precise control but are generally heavier and more complex than pneumatic actuators
• Hydraulic actuators are often used in larger-scale soft robots and in applications requiring high force (soft exoskeletons, underwater robots)

Dielectric elastomer actuators

• Dielectric elastomer actuators (DEAs) are a type of electrostatic actuator that consists of a soft dielectric material sandwiched between two compliant electrodes
• When a voltage is applied, the electrodes attract each other, causing the dielectric material to compress and expand, generating motion
• DEAs offer high strain, fast response times, and silent operation but require high voltages and are prone to electrical breakdown

Soft strain sensors

• Soft strain sensors are used to measure the deformation and strain of soft robots, providing feedback for control and monitoring purposes
• Various types of soft strain sensors have been developed, including resistive, capacitive, and optical sensors
• Examples of soft strain sensors include conductive elastomer composites, liquid metal sensors, and fiber Bragg grating sensors

Soft robotic fabrication techniques

• Fabricating soft robots requires specialized techniques and materials that differ from those used in traditional rigid robotics
• Various fabrication techniques have been developed to create soft robots with complex geometries and embedded components

Molding and casting

• Molding and casting are commonly used techniques for fabricating soft robots, involving the use of molds to shape soft materials into desired geometries
• Soft materials, such as silicone rubbers and polyurethanes, are poured into molds and cured to create soft robotic components
• Multi-step molding processes can be used to create soft robots with multiple materials or embedded components (sensors, reinforcements)

3D printing soft materials

• 3D printing has emerged as a powerful tool for fabricating soft robots with complex geometries and material gradients
• Soft materials, such as thermoplastic polyurethanes (TPUs) and silicone-based inks, can be 3D printed using various techniques, such as fused deposition modeling (FDM) and direct ink writing (DIW)
• 3D printing enables the rapid prototyping and customization of soft robots, as well as the creation of multi-material structures

Embedded components and electronics

• Soft robots often require the integration of embedded components, such as sensors, actuators, and electronics, to enable sensing, actuation, and control
• Various techniques have been developed to embed components into soft robots, such as molding, 3D printing, and micro-transfer printing
• Examples of embedded components in soft robots include flexible printed circuit boards (FPCBs), soft sensors, and thin-film batteries

Applications of soft robotics

• Soft robotics has the potential to revolutionize various fields, from healthcare and assistive technologies to manufacturing and exploration
• The unique properties of soft robots, such as their adaptability, safety, and conformability, make them well-suited for a wide range of applications

Biomedical and assistive devices

• Soft robots can be used in biomedical and assistive devices to provide safe and comfortable interactions with humans
• Examples include soft exoskeletons for rehabilitation, soft prosthetics, and soft surgical robots (minimally invasive surgery, endoscopy)
• Soft robots can also be used in wearable devices for monitoring health and providing assistance (soft sensors for vital signs monitoring, soft actuators for haptic feedback)

Grippers and manipulators

• Soft grippers and manipulators can handle delicate and irregularly shaped objects that are challenging for traditional rigid grippers
• Soft grippers can conform to the shape of the object, providing a secure and gentle grasp
• Examples of soft grippers include pneumatic bellows grippers, electroadhesive grippers, and granular jamming grippers (universal gripper)

Wearable and epidermal devices

• Soft robots can be integrated into wearable and epidermal devices, such as soft exosuits and soft sensors for human motion tracking and assistance
• These devices can be used for rehabilitation, performance enhancement, and monitoring of human activities
• Examples include soft exosuits for lower limb assistance, soft strain sensors for motion tracking, and soft actuators for haptic feedback

Soft robots in exploration

• Soft robots are well-suited for exploration tasks, such as navigating through confined spaces, adapting to unstructured environments, and interacting with delicate objects
• Examples of soft robots in exploration include soft snake-like robots for search and rescue operations, soft underwater robots for marine exploration, and soft robots for space exploration (soft rovers, soft manipulators)

Future trends in soft robotics

• The field of soft robotics is rapidly evolving, with new materials, fabrication techniques, and control strategies being developed to address the challenges and expand the capabilities of soft robots
• Several future trends in soft robotics are expected to shape the field in the coming years

Integration of smart materials

• The integration of smart materials, such as shape memory polymers, self-healing materials, and stimuli-responsive materials, can enhance the functionality and adaptability of soft robots
• Smart materials can enable soft robots to change their shape, stiffness, or other properties in response to external stimuli (temperature, light, magnetic fields)
• Examples include shape memory polymer actuators, self-healing soft robots, and magnetically responsive soft composites

Biohybrid and living robots

• Biohybrid and living robots combine soft robotic structures with living cells or tissues to create robots with unique properties and capabilities
• Living cells, such as muscle cells or cardiomyocytes, can be used as actuators to generate motion in soft robots
• Examples of biohybrid and living robots include muscular hydrostats, biohybrid actuators, and xenobots (living robots made from frog cells)

Scalability and mass production

• Developing scalable and mass-producible fabrication techniques for soft robots is essential for their widespread adoption and commercialization
• Researchers are exploring new fabrication techniques, such as high-throughput molding, 3D printing, and roll-to-roll processing, to enable the mass production of soft robots
• Standardization and modularization of soft robotic components can also facilitate their scalability and integration into larger systems

Autonomy and intelligence in soft robots

• Incorporating autonomy and intelligence into soft robots can enable them to adapt to changing environments, learn from experience, and make decisions without human intervention
• Machine learning and artificial intelligence techniques, such as reinforcement learning and deep learning, can be used to develop autonomous and intelligent soft robots
• Examples include self-learning soft robots, adaptive soft control strategies, and soft robots with embedded intelligence (neuromorphic computing, edge computing)