Application of pressure sensors in robotics

For decades, applications and services have relied heavily on vision systems and inertia to perceive and interact with the world around us. However, these modalities lack the critical human-like sense of touch.

Robots equipped with only cameras and accelerometers cannot collect surface texture data of objects, sense physical forces, or obtain proprioceptive feedback of their own movements and joint positions. This lack of tactile awareness greatly limits the robot's ability to move adaptively in complex environments, flexibly handle objects, and respond appropriately to contact between body parts and objects around it in a safe manner.

According to MEMS Consulting, it can be used to provide critical tactile feedback to robots to expand their capabilities. Continuous monitoring of pneumatic and hydraulic pressure within robot joints and actuators can provide the robot with proprioception of its own movement and torque level. This feedback allows for advanced control of movement and the application of targeted joint forces.

Coating a robot with a conformal, flexible array of pressure sensors can create an artificial sense of touch. The skin-like layer of pressure sensors can detect and map external forces from contact, human-robot interaction, or collision, allowing the robot to respond to these forces. With enough pressure data integrated into the control loop, the robot can achieve human-like dexterity and adaptability. Tactile pressure feedback can enable robots to collaborate safely and seamlessly with their human colleagues in factory environments. It also holds great promise for robotic operations in high-risk environments such as healthcare, defense, disaster relief, and space exploration, where blind automation is not feasible.

Application of pressure sensors in robotics

Pressure sensors play a fundamental role in contemporary robotics, but their value is often underestimated. Pressure sensors provide continuous monitoring of internal pneumatic and hydraulic pressures, external forces, and environmental conditions. This provides critical feedback to the robot, enhancing internal monitoring, flexible motion control, environmental interaction, and tactile perception. A key application is proprioceptive sensors, which use pressure measurements within joints to calculate applied torque and force. This information about robot motion and loads allows for more precise control, greatly enhancing the robot's manipulation capabilities and stability. Tendon-driven robots use pressure sensors to measure tendon tension, which is directly related to the force generated at the joint. More traditional robotics techniques are done by installing load cells to measure joint pressure differences and infer torque.

Some advanced systems apply ultra-small electromechanical systems (MEMS) pressure sensors directly to robot joints to provide high-resolution proprioceptive feedback. This MEMS pressure sensor technology is comparable to biological proprioception, allowing robots to be aware of their own movements and loads. Similarly, integrating MEMS pressure sensors into the outer skin of the robot can provide tactile feedback about contact forces. Large sensor arrays with multiple individual pressure sensors can help map the distribution of forces on the robot's body and their magnitude.

This large sensor array enables the robot to respond appropriately to physical contact, including gentle touch or destructive collision. This type of tactile "skin" system uses a conformal, flexible matrix of pressure sensors to provide robots with complex environmental awareness and human-like touch. Other environmental interactions can be detected using differential pressure sensors to distinguish collisions. By measuring pressure fluctuations within a fluid-filled bladder, the sensor can detect impending impact and help initiate support operations. This collision sensor technology is also applicable to soft robots that lack a solid frame. By controlling the contact force, the pressure sensors can further help the robot respond safely when it collides with itself or with humans.

Pressure sensors inside the robot monitor hydraulic and pneumatic systems to ensure that it can move. At the same time, leaks can be detected through abnormal pressure drops, allowing maintenance to be performed before the robot fails completely. Flow sensors based on the pressure difference principle can monitor the operation of pumps and pneumatics. Changes in altitude and depth can be detected through pressure differences when the robot ascends or descends. This sensory feedback supports reliable and stable mobility. In addition, if the robot works outdoors or in harsh environments, pressure sensors can make it weather-resistant.

Installing a MEMS pressure sensor with a waterproof membrane inside the robot can quickly detect water ingress caused by rain or flooding before components are damaged. The robot can then take action to protect internal components or send out assistance.

Technological innovation drives progress

Several major advances in technology have facilitated the realization of more common and powerful applications of pressure sensors in the field of robotics. MEMS manufacturing allows the use of high-resolution and extremely compact differential pressure sensors that can integrate proprioception into robot joints and actuators. For example, Superi Sensor chnology's MEMS pressure sensors integrate advanced functions including advanced digital filtering, closed-loop control, and software-based pressure switches. In a fully integrated form, these sensors provide the essential internal torque and force feedback required for precise motion control and flexible object manipulation capabilities.

Flexible pressure sensor arrays printed with quantum tunneling composites, graphene or other nanomaterials can also make the skin layer covering the robot conformal and stretchable. Sensor skin made of materials such as latex infused with nanotubes can be stretched over complex joints and surfaces. This artificial sense of touch using flexible printed sensors can perform dense pressure mapping with high spatial resolution throughout the robot's body. Precise skin-like tracking allows robots to safely detect, react and interact with humans in collaborative work scenarios.

Regarding data processing, advanced (ML) methods such as deep learning can be used to optimize control and response using real-time pressure data from sensor arrays. Computational models use pressure patterns from proprioception and tactile sensors to transmit reflex responses and command arm movements. For example, one study used reinforcement learning of pressure input to train a robotic arm with highly dexterous manipulation skills, such as rolling a ball in the palm of the hand.

New soft actuators and grippers using fluid elastomer technology rely heavily on monitoring pressure across the structure for precise control and feedback. These pneumatic soft robotic actuators with integrated pressure sensors can be used to smoothly adapt to the object being grasped. This technology allows for safer physical human-robot collaboration in shared work scenarios, where the use of traditional rigid robots would be risky.

As various technological innovations develop, pressure sensors are expected to become an important integrated feedback mode embedded in future robotics, from robots to medical devices. People are beginning to understand the potential of artificial touch sensors to achieve responsive and adaptive robots.

Future robots: human-like tactile sensing

As pressure sensors and integration technologies continue to advance, robots with artificial touch sensing will revolutionize many fields:

Human-like dexterity: With enough tactile pressure data, robots can achieve very human-like dexterity, manipulating objects of various weights, textures, and shapes. This dexterity will drive automation in manufacturing, warehousing, surgery, and more.

Operations in hazardous environments: Durable robots with integrated pressure sensors can perform high-risk tasks such as mining, deep-sea exploration, disaster response, and space missions where direct human involvement would be extremely dangerous. Pressure data helps robots respond to various complex environments and better adapt to them.

Seamless human-robot collaboration: Ultra-sensitive pressure sensor skins will enable future robots to collaborate safely and seamlessly with their human colleagues. During physical interactions, pressure feedback suppresses harmful contact forces.

Infrastructure: Robotic inspectors with integrated pressure sensor skins could be used to monitor wind turbines, oil pipelines, bridges, and other infrastructure. Pressure data could alert of any developing failures.

Medical Applications: Tactile pressure sensors will facilitate breakthroughs in robotics applications such as surgery, prosthetics, rehabilitation, and assistive robotics, where safe interaction with humans is critical.

As costs decrease and integration technology improves, tactile pressure sensors may be integrated with vision, position, and inertial sensors to become the standard sensing modality for advanced robots. Pressure sensors enable future capable and usable robots to operate efficiently and safely alongside humans in the dynamic real world.

in conclusion

Pressure sensors provide key capabilities for robots, including tactile sensing for responsive interactions and proprioception for dexterous manipulation. At the same time, the pressure sensors' continuous monitoring of internal hydraulic pressure, external contact forces, and environmental conditions provides pressure data, enabling robots to move, handle objects, and respond to physical stimuli with human-like sensitivity.

The continued development of flexible printed arrays, MEMS sensors, and machine learning integration will promote breakthroughs in multimodal robot perception and seamless human-robot collaboration. As costs decrease, pressure sensors show a bright future for integrating standard feedback modes into future robot designs, with applications ranging from medical, industrial, auxiliary, hazardous environments, and infrastructure monitoring. Pressure sensors provide robots with the feedback they need to operate reliably, safely, and intelligently in the dynamic physical world, which has great potential for application development.