Design and Test of a Microdestructive Tree-Ring Measurement System

Abstract

Analysis of a tree ring is the primary method for determining the growth and age of a tree. In a microdestructive tree-ring measurement system, the tree under test is drilled with a microdrill at a constant rotating speed to detect the difference in density between the early and late wood, thereby realizing a microdestructive measurement of the tree-ring. The measurement system comprises a microdrill with a diameter of 3 mm, mechanical transmission, direct current (DC) servomotor, stepper motor, and control and detection circuit. The DC servomotor and stepper motor realize rotation and translation of the microdrill, respectively, through mechanical transmission. When the microdrill rotates and drills into the tree, the control and detection circuit samples and acquires the armature current of the DC servomotor, which is proportional to the resistance encountered by the drill bit and reflects the change in the density of the tree. The tree-ring number can be obtained by filtering the sampled original signals of the armature current using a finite impulse response (FIR) filtering algorithm. The annual rings of larch and fir tree discs were measured and tested using the designed system. It was observed that the average annual ring measurement accuracy of the larch discs reached 95.28%, while that of the fir discs was 84.16%. The diameter of the drill hole in the trunk was less than 3 mm after measuring the living wood, thereby achieving a microdestructive measurement of the tree-ring.

Research on Tree Ring Micro-Destructive Detection Technology Based on Digital Micro-Drilling Resistance Method

“…The analog method solves the disadvantage that the mechanical method cannot quantify the results and has become a widely used method for micro-drilling resistance technology. The design principle of the tree ring micro-destructive detection equipment published by Hu, X and Chen, X can be considered the analog method [39,40]. Currently, the tree ring micro-destructive detection system designed by Beijing Forestry University (BJFU) and the tree-ring acupuncture instrument designed by the Chinese Academy of Forestry (CAF) are both designed by the analog micro-drilling resistance method.…”

“…On the contrary, the activity of cambium cells is significantly weakened in autumn and winter, and the formed xylem cells become narrow, thick, and fiber-rich. Therefore, the part of the tree ring in autumn and winter is dense in texture with a darker color, habitually called latewood or autumn wood [39].…”

“…The experimental equipment adopts the hand-held mechanical structure and dualmotor transmission structure shown in Figures 5 and 6, similar to the mechanical structure proposed by Hu X. in [39]. The DC motor drives the micro-drill to rotate at high speed.…”

“…For the widely used and fully disclosed analog micro-drilling resistance method, the main factor that affects the detection and identification accuracy is the excessive noise interference in the output signal [39,40]. The signal in the analog method transmits in analog quantities form, which results in poor anti-interference ability.…”

Effects of micro-drilling parameters on the drilling force and pore morphology of Sapindus mukorossi seeds

“…For woody materials, micro-drilling has mainly been used as an inspection technique. An example of this is the micro-drilling resistance method for wood (which is a micro-damage inspection technique) (Li et al 2019;Hu et al 2020;Hu et al 2022). Research on the process parameters of micro-drilling of woody materials, such as S. mukorossi seeds, is lacking.…”