8.8 Soft robotics
7 min read•august 20, 2024
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 .
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, , 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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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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Frontiers | Modeling of Deformable Objects for Robotic Manipulation: A Tutorial and Review 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 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 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 and reinforced composites
Soft actuators and sensors
- 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
- 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
- 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
- (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
- 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
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
- has emerged as a powerful tool for fabricating soft robots with complex geometries and material gradients
- Soft materials, such as (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), , 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 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 , 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)
Key Terms to Review (28)
3D Printing: 3D printing is a revolutionary additive manufacturing process that creates three-dimensional objects by layering materials based on digital models. This technology enables the production of complex geometries and tailored structures, making it an essential tool in various fields, including biomedical engineering, where it can fabricate custom implants and organ models.
Actuation Efficiency: Actuation efficiency refers to the effectiveness with which a soft robotic system converts input energy into mechanical work or movement. This concept is critical in soft robotics, as it determines how well a soft actuator can respond to control signals and perform desired tasks while minimizing energy consumption. A high actuation efficiency indicates that more energy is effectively utilized for motion, which is particularly important for enhancing the performance and longevity of soft robotic systems.
Adaptive control systems: Adaptive control systems are control systems that adjust their parameters automatically in response to changes in the system dynamics or environment. This capability allows them to maintain optimal performance even in the presence of uncertainties, making them particularly valuable in applications where conditions are variable or unpredictable. Such systems are crucial in fields like robotics and automation, where adaptability is essential for effective operation.
Bio-inspired design: Bio-inspired design refers to the practice of drawing inspiration from the structures, functions, and strategies found in nature to solve human challenges and create innovative solutions. This approach leverages the lessons learned from biological systems to inform the design of products, materials, and technologies, resulting in more efficient, sustainable, and adaptable designs. By mimicking the principles of evolution and natural selection, bio-inspired design fosters creativity and innovation across various fields, including robotics and engineering.
Biohybrid robots: Biohybrid robots are advanced robotic systems that integrate biological components with artificial structures, creating a synergy between living organisms and machines. This combination allows for enhanced functionality, adaptability, and the potential for self-healing, mimicking biological processes and characteristics. These robots leverage soft robotics principles to interact safely with their environment, opening up new possibilities in fields like medicine, environmental monitoring, and bioengineering.
Biomimicry: Biomimicry is the practice of designing systems, products, or processes inspired by nature's models, systems, and elements. It connects the ingenuity of natural organisms and ecosystems to innovative solutions for human challenges. By studying how nature solves problems, biomimicry promotes sustainability and efficiency in technology and engineering, leading to advancements like soft robotics that mimic the flexibility and adaptability found in living creatures.
Compliance: Compliance refers to the ability of a material or system to deform under applied stress and return to its original shape when the stress is removed. In the context of soft robotics, compliance is a crucial feature that allows soft robots to interact safely and effectively with their environment, adapting to different shapes and conforming to the objects they encounter.
Continuum mechanics: Continuum mechanics is the branch of mechanics that deals with the behavior of materials modeled as continuous mass rather than discrete particles. This approach allows for the analysis of materials under various forces and deformations, making it essential in understanding how materials respond to stress, strain, and external forces. Continuum mechanics plays a significant role in various fields, including engineering, physics, and specifically in soft robotics, where flexible materials mimic biological systems.
Cynthia Breazeal: Cynthia Breazeal is a pioneering roboticist known for her work in social robotics and human-robot interaction. She has been instrumental in developing robots that can engage with people in a socially meaningful way, contributing significantly to the field of soft robotics, where flexibility and adaptability are key features for creating robots that can interact more naturally with humans.
Dielectric elastomer actuators: Dielectric elastomer actuators (DEAs) are a type of soft actuator that utilize the deformation of dielectric elastomers in response to an electric field to produce mechanical motion. These actuators are significant in soft robotics due to their lightweight, flexible, and energy-efficient nature, allowing for dynamic movement and adaptability in various applications. DEAs can mimic biological muscle movements, making them ideal for creating soft robotic systems that require gentle interaction with their environment.
Embedded components: Embedded components refer to integrated elements within a system that are designed to perform specific functions while being part of a larger structure. In the context of soft robotics, these components can include sensors, actuators, and control systems that work together to create flexible and adaptive robotic systems. Their design allows for seamless integration with soft materials, enabling enhanced functionality and responsiveness in varying environments.
Hiroshi Ishiguro: Hiroshi Ishiguro is a prominent Japanese roboticist known for his work in humanoid robotics and social robots. He is particularly famous for creating lifelike robots that can engage in human-like interactions, blurring the lines between humans and machines. His innovations in soft robotics highlight the potential for creating flexible, adaptable robots that can be used in various applications, from healthcare to companionship.
Hydraulic actuators: Hydraulic actuators are devices that convert hydraulic energy into mechanical motion, using pressurized fluid to create movement. They are essential components in various applications, including soft robotics, where they enable the creation of flexible and adaptable movements that mimic natural organisms. By manipulating fluid flow and pressure, hydraulic actuators provide the strength and precision needed for tasks that require delicate handling or powerful force.
Hydrogels: Hydrogels are three-dimensional polymer networks that can absorb and retain significant amounts of water while maintaining their structure. Their unique properties allow them to be used in various applications, including drug delivery systems, tissue engineering, and biosensors, where they can interact with biological environments.
Material Durability: Material durability refers to the ability of a material to withstand various environmental conditions and mechanical stress over time without significant degradation. In soft robotics, this concept is crucial as it determines how long the materials can perform effectively under repetitive use and exposure to different elements, which influences the overall reliability and functionality of soft robotic systems.
Medical devices: Medical devices are instruments, apparatuses, machines, or implants used in healthcare for diagnosis, prevention, monitoring, treatment, or alleviation of diseases and disabilities. They encompass a wide range of products from simple bandages to complex imaging systems and robotic surgical tools. The development and application of medical devices are increasingly influenced by advances in technology, including soft robotics, which enhances the functionality and adaptability of these tools in clinical settings.
Molding and Casting: Molding and casting are manufacturing processes used to create parts and products by shaping liquid materials into specific forms. In soft robotics, these techniques enable the creation of flexible, lightweight structures that can mimic biological movement and adapt to various tasks, making them essential for developing innovative robotic systems that operate safely around humans.
Morphing: Morphing refers to the gradual transformation of one shape or form into another, often used in soft robotics to describe how materials can change their configuration and adapt to different environments or tasks. This ability to alter physical characteristics allows soft robots to navigate complex terrains and manipulate objects with ease, showcasing flexibility and adaptability in their design.
Pneumatic Actuators: Pneumatic actuators are devices that use compressed air to create motion and force in various applications. They are commonly used in soft robotics due to their lightweight, adaptable, and flexible nature, allowing for gentle interactions with delicate objects and environments. This ability to mimic natural movements makes pneumatic actuators an integral part of designing soft robotic systems that require compliance and adaptability.
Search and rescue: Search and rescue (SAR) refers to the coordinated efforts to locate and assist individuals in distress, particularly in emergency situations. This concept is crucial in various fields, including disaster response and recovery, where swift action can save lives. The effectiveness of search and rescue operations often relies on advanced technologies, including robotics, to enhance efficiency and reach inaccessible areas.
Self-healing materials: Self-healing materials are innovative substances designed to automatically repair damage to themselves without external intervention. This capability can significantly enhance the durability and longevity of materials used in various applications, especially in soft robotics, where flexibility and resilience are crucial. By mimicking biological processes, these materials can restore their original properties after being damaged, making them invaluable in scenarios where maintaining structural integrity is vital.
Shape Memory Polymers: Shape memory polymers (SMPs) are smart materials that can 'remember' their original shape and return to it after being deformed when exposed to specific stimuli, such as temperature changes. This unique property allows SMPs to undergo significant shape changes while remaining lightweight and flexible, making them highly applicable in various fields, particularly in soft robotics where adaptable and responsive materials are essential for functionality and performance.
Silicone elastomers: Silicone elastomers are flexible and durable synthetic polymers made primarily from silicon, oxygen, carbon, and hydrogen. These materials are notable for their exceptional elasticity, thermal stability, and resistance to various environmental factors, making them ideal for a wide range of applications, particularly in soft robotics. Their unique properties allow for soft and adaptable structures that can mimic biological systems and enhance functionality in robotic designs.
Soft actuators: Soft actuators are flexible devices that can produce controlled movements or forces, utilizing soft materials to mimic the functionality of natural systems. These actuators play a crucial role in soft robotics, allowing for safe interaction with delicate objects and environments, making them ideal for applications in healthcare, search and rescue, and manipulation tasks.
Soft grippers: Soft grippers are flexible robotic devices designed to grasp and manipulate objects of varying shapes and sizes without damaging them. These grippers utilize soft materials and often mimic biological systems, such as the way an octopus or a human hand functions, to achieve dexterous manipulation. Their unique design allows for adaptability and gentle handling, making them ideal for tasks in delicate environments like medical applications, agriculture, and service industries.
Soft Sensors: Soft sensors are computational models that estimate unmeasured or hard-to-measure physical properties in real-time using data from other sensors. They are crucial in soft robotics, where traditional rigid sensors may not be suitable due to flexibility and adaptability requirements. Soft sensors provide enhanced data interpretation and decision-making, allowing for more nuanced control in dynamic environments.
Soft strain sensors: Soft strain sensors are flexible and lightweight devices designed to detect and measure deformation or strain in materials, particularly in soft robotics applications. These sensors can respond to mechanical changes in their environment, enabling soft robots to perceive their surroundings, adapt to different shapes, and perform intricate movements. Their integration into soft robotics systems enhances functionality by allowing for precise feedback on the robot's movements and interactions.
Thermoplastic polyurethanes: Thermoplastic polyurethanes (TPUs) are a class of versatile elastomers known for their unique combination of flexibility, durability, and processability. They can be easily molded or shaped upon heating, allowing for a wide range of applications, especially in soft robotics, where lightweight and flexible materials are crucial for creating adaptable and dynamic structures that mimic biological movement.