Investigations On The Flexible Sensor Used On Measurement Of Human Motion

It is an important content in the field of robotics bionics research to deeply understand the laws of human natural movement and to reshape and improve the ability of human movement,and it is also an important application of robotics technology.The optical motion capture system can accurately measure human motion,but it is difficult to be applied in complex real environment due to the limitation of laboratory fixed space.Wearable technology can be applied to various motion environments by virtue of a good humanmachine combination,but it requires that the sensor can be deformed according to the motion of musculature and bone system.At present,flexible sensors are inconvenient in practical uses as they usually require calibration every time they are installed.And there is currently no flexible sensor that can be used for human underwater motion measurement and human muscle deformation.Focusing on the key issues of flexible sensors in human motion measurement,such as repeated calibration and single use scenario,this thesis includes the following researches:(1)Principle of sensing: For human joint articular movements measurement,a flexible curvature sensor is designed based on the capacitive sensing principle.The sensing method of articular rotation angles employs the Euler beam model to make the sensor reusable after one-time calibration.For human muscle deformation measurement,an existing highly sensitive flexible pressure sensor with microporous is adopted.The dielectric layer microporous can not only reduce its elastic modulus,but also increase the dielectric constant during compression,thereby significantly improving the sensitivity of the sensor.(2)Fabrication process: The curvature sensor employs polyurethane resin or PDMS as the dielectric layer and liquid alloy(EGaIn)as electrodes.The liquid electrode is encapsulated in the elastomer with shape deposition molding(SDM),which makes the sensor waterproof.The dielectric layer of the pressure sensor is processed by melting sugar particles to form uniform micropores.(3)Measurement of human motion: The flexible curvature sensor can accurately measure human knees and ankles amphibious movements.The root-mean-square error is within 5° for different walking mode and the maximum error is with 3.5° for underwater sensing.Two kinds of sensors were used to measure articular movements and muscle deformation,showing that the ankle angle was positively correlated with the deformation of gastrocnemius.The problem that the sensor needs to be calibrated repeatedly before using was solved by the flexible curvature sensor,and its waterproof performance breaks through the limitation of using underwater.The highly sensitive flexible pressure sensor can be applied to the muscle deformation measurement.The precise measurement and the good manmachine combination of the sensor can provide more abundant research data for the study of human motion,which can also provide real-time motion signal for the exoskeleton robot,improving the feedback control effect,and promoting the development of the exoskeleton robot.