Optimization design of airflow arrangement device for shiitake mushroom based on dynamic modeling and simulation

https://doi.org/10.1016/j.compag.2022.106899Get rights and content

Highlights

  • A novel arrangement device for shiitake mushroom using airflow is proposed.

  • Aerodynamics of the mushroom in airflow is analyzed.

  • The principle of the method is revealed by dynamics modeling.

  • Device parameters are optimized based on Monte Carlo simulation.

Abstract

As there is no mature agricultural automation device for trimming roots and stipes of shiitake mushrooms, this paper proposes a novel arrangement method to improve its processing efficiency. A dynamic model of shiitake mushrooms in airflow is established to analyze their motion states to assess the feasibility of this methodology, and computational fluid dynamics is used to establish aerodynamic coefficients. The dynamic model presents the relationship between the motion state and the airflow. In this device, a stable state is needed, which means the shiitake mushroom should maintain its stipe pointing up. Then the Monte Carlo simulation method is conducted to optimize the device to achieve a high probability of stipe upward with an appropriate length of ventilation duct and wind velocity. Thus, our methodology can be effectively used to arrange mushrooms for further application in a trimming and separation device.

Introduction

Shiitake mushroom is an important crop as an edible and medical mushroom (Cheung, 2010, Nunes et al., 2012, Rahman and Choudhury, 2013). With its annual output increases year by year (China Edible Fungi Association, 2018), agricultural automation equipment has been gradually adopted the fields which involve shiitake mushrooms. Usually, the caps, roots, and stipes are segregated manually in the shiitake mushrooms processing, which is labor-intensive and inefficient. It is essential to develop automated industrial equipment to solve these problems. Industrialization means that shiitake mushrooms should be placed with the same posture rather than randomly. The mushrooms’ morphology varies greatly and their structure is fragile, therefore arranging them effectively becomes a challenging work.

The existing methods usually use vibration or stir, which have some obvious disadvantages. Reed et al. (2001) developed a method of positioning each mushroom onto a conveyor at a vertical height that was proportional to the cap height. Wang et al. (2018) designed a vibration screen to guide the mushrooms individually onto the conveyor along the guide plate. The technique will bruise the surface when fixing them. Moreover, variable size mushrooms cannot be well matched onto the gripping unit, which reduces the efficiency. Consequently, it is necessary to design a device to achieve efficient adjustment of mushroom posture without damaging its surface. Airflow can be used for sorting, picking, and arranging food products. For example, air dense medium fluidized bed is extensively applied in agricultural products (Sivakumar et al., 2016). Soponronnarit et al. (2006) designed an experiment of a pilot-scale superheated-steam fluidized bed dryer to parboil rice. Sakurai et al. (2017) used a top-spray fluidized bed granulator to enhance the surface properties of green tea powder. Van De Vegte and Renfrew (2017) created a mushroom harvester to supply negative air pressure to the suction gripper for retaining a cap of the mushroom to be harvested in the suction cup. Wang et al. (2018) produced an automatic mushroom sorting system using airflow to push the mushrooms into a container. Inspiring by these inventions, we figure out a new idea to arrange shiitake mushrooms by airflow. When the shiitake mushrooms fall into a duct full of airflow, they will achieve a consistent posture after being affected by the airflow. The device can be used for different size shiitake mushrooms and prevents their surface from being bruised.

In order to theoretically analyze the device’s function, an investigation of the dynamic process of shiitake mushroom in the ventilation ducts is inevitable, but relevant studies have not been reported. Commonly used dynamic modeling methods are Lagrange dynamic equations and Newton-Euler equations. Lagrange dynamic equations describe the differentiation of the energy of a mechanical system with respect to the system variables as well as time (Teng et al., 2021). Newton-Euler equations describe the combined translational and rotational dynamics of a rigid body (Balafoutis and Patel, 1991). It relates the motion of the center of gravity (CG) of a rigid body to the sum of the force and moment acting on it, and the physical meaning is clear. Therefore, the Newton-Euler equations are chosen to calculate motion states after the aerodynamic force and moment of the mushroom in the airflow have been computed.

Computational fluid dynamics (CFD) is a numerical method that has been widely used in manufacturing (Dehbi et al., 2013, Farhat, 2017, Wu et al., 2007). It has been applied in establishing a table of the force and moment during the shiitake mushroom falling process. Srivastava (1997) simulated eighteen widely varying wind tunnel conditions, including geometric changes, angles of attack, and windward and leeward jet-on and jet-off to show the normal force and moment coefficients for all cases were in excellent agreement with the experiment data. DeSpirito and Heavey (2004) accurately predicted the Magnus moment and roll damping of the M910 projectile through CFD parameters. Lin and Schohl (2004) gave the predicted hydrodynamic force coefficients of disc butterfly valves under different valve working angles. De Barros et al. (2008) used CFD to provide a good prediction of the bare hull’s normal force and moment coefficient. There are also researches in the food processing industry. Abdul Ghani et al. (2001) simulated the transient temperature, velocity profiles, and the shape of the slowest heating zone in sterilization of carrot soup pouches with CFD. A three dimensional CFD model by Xu and Burfoot (1999) could predict the condensation of vegetables. It can be seen that CFD is an appropriate method for calculating the force and moment of shiitake mushrooms falling through a ventilation duct.

After the aerodynamic coefficients are calculated by CFD for dynamic modeling, we need to further optimize the designed device. The Monte Carlo method generates random events by a computer model, and the process is repeated many times and the occurrence number of a specific condition is counted (Zio, 2013). Due to time-consuming, high cost, and complicated operation of the modeling and manufacture of different size ventilation ducts, Monte Carlo simulation is a good method for the parameter optimization.

Towards this end, the main contribution of this work is that we propose an innovative methodology for arranging shiitake mushrooms with airflow, build the whole dynamic model, and optimize the device’s parameters. In contrast with previous techniques, our method has a higher arrangement efficiency and will not bruise the shiitake mushrooms.

This paper is organized as follows. The description of the experiment using airflow for arrangement is given in Section 2. Section 3 establishes the dynamic model of shiitake mushrooms. Section 4 calculates the aerodynamic forces and moments of the shiitake mushrooms. Section 5 counts the steady state of the shiitake mushrooms in the dynamic model and provides Monte Carlo simulation results to optimize the device parameters. Section 6 concludes this work.

Section snippets

Experimental of airflow arrangement

In order to verify the principle that a certain velocity of airflow can change the attitude of mushrooms, we design an experimental device shown in Fig. 1. This device includes a transparent ventilation duct and an upward airflow generator. The duct’s radius is 55 mm, and its height is 500 mm. Once the mushroom falls into the ventilation duct, its posture quickly changes, and the attitude stabilizes when its stipe is up in the airflow.

Dynamic model

For theoretical analysis and optimal design, we need a dynamic model to simulate the movement of mushrooms, which is shown in Fig. 2. It is composed of the aerodynamic module, the gravity module, the equation of motion module, and the virtual reality module. The six-degree-of-freedom equation of motion calculates the motion state of the shiitake mushroom according to the resultant force f and moment m, where f is the sum of the aerodynamic force fa and gravity g. The aerodynamic module derives

Aerodynamics of shiitake mushroom

In order to compute the aerodynamic forces and moments of shiitake mushrooms, CFD is utilized to simulate fluid flow and describe the characteristics of the flow field. We have investigated the forces and moments for varied mushroom models and fluid characteristics in ventilation ducts under different inlet velocities to determine the dynamic equations’ inputs.

Derivation of stable state

For a given initial state, the dynamic simulation is carried out to analyze the motion process and output motion states such as Euler angle η and displacement Xe.

Suppose the initial Euler angles randomly with zero initial angular velocities, we find that the mushrooms reach two stable states of their attack angle α=0 and α=π, which indicate the stipe upward and stipe downward. As shown in Fig. 12, when α initially equals 14π, it quickly stabilizes at α=0, which means stipe is down over time.

Conclusion

In this paper, a novel methodology for arranging shiitake mushrooms using airflow is proposed. This device can efficiently adjust the posture of the shiitake mushroom without bruising its surface and make its root and stipe get ready to be trimmed. A dynamic model of the shiitake mushroom has been established to analyze its movement in the flow field. The six-degree-of-freedom motion equation is established, and the ANSYS, the computational fluid dynamics simulation software, is used to

CRediT authorship contribution statement

Binbin Wang: Methodology, Software, Validation, Formal analysis, Writing – original draft. Lei Zhang: Conceptualization, Methodolgy, Supervison, Funding acquisition. Yuan Yuan: Validation. Zhiqi Zhao: Investigation. Haijiao Nan: Data curation.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgment

This work is supported in part by the National Natural Science Foundation of China under Grant 61773008 and the Fund of Henan Province Young Key Teacher under Grant 2019GGJS032. Thanks for all your support.

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    School of Physics and Electronics, Henan University, Jinming Avenue, Kaifeng 475001, PR China.

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