Wood Inertial Measurement Unit Based on Laser-induced Graphene
Inertial Measurement Unit(IMU)mainly measures and reports the specific force and angular velocity of an object.It usually consists of a three-axis accelerometer and a three-axis gyroscope.Traditional IMU have complex manufacturing processes and high costs.It is not easy to recycle,pollute the environment and cannot be biodegradable after being discarded.In this study,a kind of wood inertial measurement unit based on Laser-induced Graphene(LIG)is proposed.Camphor pine wood was selected as the sensor frame.The pine is placed in the vacuum chamber and adjust the vacuum degree in the vacuum chamber.Fiber laser and laser vibrators software was used to process LIG resistors at the pine frame resistor locations by adjusting laser frequency,laser power,scan speed,off-focus distance and other parameters,with a resistance value of about 100 Ω,and to connect these resistors into multiple Wheatstone bridges.Due to the sensor's design being symmetrical along the X-and Z-axes,only the Wheatstone bridge on the beam in the X-or Z-axis direction needs to be measured.Different inertial bodies are divided into balanced oscillator unit and unbalanced oscillator unit.The inertial body of the balanced oscillator unit is a spherical inertial body(Cr13),mainly measuring acceleration;The inertial body of the unbalanced dipole element is the inertial wheel(PLA),which mainly measures the angular acceleration.The theoretical formula shows that the acceleration range of IMU along X axis and Z axis is±10 g,the acceleration range along Y axis is-g～+3 g,the angular acceleration range around X axis and Z axis is±8 rad/s2,and the angular acceleration range around Y axis is±23 rad/s2.The product of this study is placed on a sports platform and uses a dynamic signal acquisition system to collect the output voltage of a Wheatstone bridge in the IMU.Through the joint test and comparison of the commercial acceleration sensor and unbalanced oscillator unit,it can be concluded that the designed sensor has the same change as the commercial sensor and has the ability to measure the angular rate.The results of this measurement of the Wheatstone bridge on the Z-axis beam are as follows:The sensitivity of the X-axis acceleration of the balanced oscillator unit is 0,and the sensitivity of the Y-axis acceleration is 8.695×10-4 mV/g,the Z-axis acceleration sensitivity is 0.200 mV/g,and the sensitivity to angular acceleration is 0.The sensitivity of Y-axis acceleration of the unbalanced oscillator unit is 1.110 mV/g,the sensitivity of the X-axis and Z-axis acceleration is 0,the sensitivity of the angular acceleration around the X-axis is 0.285 mV/(rad/s2),the sensitivity of the angular acceleration around the Y-axis is 0.305 mV/(rad/s2),and the sensitivity of the angular acceleration around the Z-axis is 0.765 mV/(rad/s2).By comparing the voltage output of Wheatstone in all directions of IMU under cyclic load,it is concluded that IMU of this design still has the ability to measure the angular rate and other parameters under multiple cyclic loads,so this design has a certain stability.We propose a wooden inertial measurement unit based on laser-induced graphene,which is made of biodegradable materials and has good sensitivity and certain stability.Compared to the IMU on the market,it is more environmentally friendly,cheaper,and more convenient to manufacture,with environmental advantages and market prospects.It can be used in the fields of wooden ships,vehicle engineering,or wooden buildings that require vibration measurement.In future research,the size of this wooden IMU can be further optimized,and element doping can be applied to LIG varistors to improve their conductivity and sensitivity.
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