Design of a new semi-automatic moss removal machine

Qing-ying ZHANG，Xin LI，Ru-zhou LI，Xiao-yu YU（Wuhan University of Technology，Wuhan 430063，China）

Design of a new semi-automatic moss removal machine

Qing-ying ZHANG*，Xin LI，Ru-zhou LI，Xiao-yu YU
（Wuhan University of Technology，Wuhan 430063，China）

Cleaning the moss on the side of the river need to spend a lot of manpower and material resources，but the removal tools are simple and inefficient.So our project team has designed a semi-automatic moss removal machine.The paper describes the structure of the machine and its working principle.The machine is easy to operate，high-effective and practicable.So it largely solved the existing safety problems.

Semi-automatic，Transverse feeding part，Vertical feeding part，Scissors mechanis

Hydromechatronics Engineering

http：//jdy.qks.cqut.edu.cn

E-mail：jdygcyw@126.com

1 Introduction

Cleaning the moss has been drawn people’s attention gradually.Through our on-the-spot investigation，Our project has learned the cleaning tools are very simple and primitive，such as shovel，brush and so on.Obviously the existing cleaning way cannot resolve the hidden security problems and spend a lot of manpower and time.So to ensure the safety of all people visiting the river，the moss on the side of rivers should be cleaned effectively and timely.

According to this situation，our project has designed a semi-automatic moss removal machine.It is easy to use and reduce the labor and time.So it has solved the existing safety problems to a great extent.

2 The whole Structure and principle of the machine

2.1 The whole structure

As is shown in Fig.1，this machine has four major parts：cleaning part，transverse feeding part，vertical feeding part and body part.

Fig.1 The whoIe structure of the machine

2.2 Working principle

All components are inside the car body when the machine is in the initial state.To make this machine operate，firstly，the operators open the front panel，X-type fork bracket 8 is in a compressed state，turn the handle to adjust the positon of the bracket 8，make the cleaning device out of the car body.Then press the switch of brush motor 6，gear motor drives the cleaning brush head spin.Press the switch on DC feeding motor 12，adjust the distance between the cleaning brush head and the ground.When the pressure of the brush head gets the set pressure，automatic control circuit of the single chip computer close the DC feeding electric machine，the equipment begins operation.The operator runs the machine through the push rod. The wheels complete the cleanup with rotating 360 degrees freely.After the work completed，turn the handle reversely to make the horizontal and vertical feeding parts back.Close the front plate or continue using solar energy to charge the battery［1］.

3 Design of main parts

3.1 Design of cleaning parts

Cleaning brush head and motor spindle are fixed with each other directly.The motor drives the brush working directly.When the direction of the brush head maintains the original state，the moss can be completely cleaned through the lifting device.

3.1.1 Calculation of the brush motor torque

The torque of the brush is mainly the friction resistance moment T from surface of steps.The calculation formula is：

μ is coefficient of friction，value range for 0.2 to 0.3；R is brush tray radius’s value，taken 0.15 m；F is the pressure of the brush head with the surface of river steps，taken 234 N after test.Taken into the formula，so the total torque is：

3.1.2 Determination of brush motor power

After test，the speed is 300 r/min，the value of vibration magnitude was the smallest and the cleaning effect is good.Therefore，considering power consumption，the speed of the brush head is n=300 r/min.So the effective power of the brush：

Pw=T·n/9 550=0.220 kW=220 W

The efficiency of gear shaft is：η=η1η22η3，η1，η2，η3 are respectively transmission efficiency of flexible shaft，antifriction bearing，straight gear（precision of 8），by the design handbook［2］，we can get：η1= 0.90，η2=0.99，η3=0.97，The power for the motor：

3.2 Design of transverse feeding device

Transverse feeding device mainly includes X-type fork brackets and transverse driving part.The double guide rails are installed on the fixed support plate，the activities end point are installed on both sides of the scissors fork organization.One side by the way of hinged or fixed at one end of guide rail，the other side is connected to a guide on the slider.The backend support plate is connected with both ends of the slider，the connection sliders open with threaded holes，which cooperate with thread on the screw rotates.By using the principle that screw transmission provides power［3］，its structure is as follows.

Fig.2 The structure of the transverse feeding device

3.3 Analysis of X-type fork brackets’s correlation paremeters

The x-type fork’s structure diagram is shown in Fig.2.In order to make the cleaning device stretch out and back between 200 mm and 800 mm.According to the geometric relations，the bracket rod under the limit of position angle should satisfy［4］：

θ1is support full contraction angle；θ2is the stent dilatation angle；L is bracket length.the change of X-type shear fork bracket angle is 11.5°-51.3°.

Suppose that the horizontal velocity of turning handle is Vx，the shear fork extending speed is Vy.By the function relation between the triangle available：

x is x-type brackets mechanism in the length of the horizontal direction；Y is x-type brackets mechanism longitudinal length；θ is supported rod and the fixed support plate angle.There is no actual meaning in the minus sign，note k=2cotθ，so we can conclude：Vy= -kVx.By θ=11.5°-53.1°，range of k can be obtained as followed：0.75-4.9.

3.4 Design of vertical feeding part

Vertical feeding device includes DC feeding motor，gear and rack，feeding guide rails support frame，linear guide rail，support platform and a feeding device control system.Methods guiding rail support frame connected by bolts feed is fixedly connected on the fixed platform.Feeding motor flange type mounting support frame at the outer end of the left guide rail feeding.The gears are arranged on the main shaft，the rack is fixedly connected with the lower end of the supporting frame in the activity，the gear and the rack with transmission.Its structure is as follows.

Fig.3 Design of verticaI feeding part

3.4.1 Calculation of motor power

This mechanism requires more accurately control feeding distance and step motor can provide a driving force.When the mechanism executes ascending motion，force analysis is shown in the Fig.4.

Fig.4 Force anaIysis

N1and N2for the elastic of the lifting object by linear guide rail.f1and f2for the lifting object by friction.F for vertical feed motor through the gear transmission to drive the rack.G for the total weight lifting object，suppose G=60 N.F for the lifting object in the inertial force generated by the rise of acceleration，suppose thatliftingobject’saccelerationais 0.1 m/s2.so the inertial force：

Fi=m·a=6*0.1 N=0.6 N

On this point of design calculation，taking into account the guide force is small，and small friction coefficient.Therefore，we can ignore the effect of friction on feed movement.According to the Darren Bell principle，by the vertical force balance：

F*cosφ-G-Finertia=0

By selection of standard driven gear and rack，pressure angle：Φ=20°.Substituting the data solution，F=60.6 N.Suppose a gear diameter is d=60 mm，safety coefficient is selected s=1.5，the shaft of the motor by the resistance moment：

60.6 ×0.025×1.5 N·m=2.28 N·m The gear speed：

3.4.2 Design of feeding control system

To realize the signal transmission，the pressure sensor［5］is installed in the backend of the cleaning brush through the guyed collector device.The sensor get the pressure information from the brush head and transform it into current information，make current implication，process and send it to MCU.MCU send the instruction into the feeding motor after analysis，processing and transformation.

MCU controller installed in the support platform can achieve signals got from the pressure sensor and send instructions into the motor，making it the instruction and form a simple closed loop system in this way. The pressure sensors collect the pressure of the brush head dynamically.when the pressure is greater than the minimum value set，MCU will stop feeding instruction and the motor stops feeding.Implementation process as shown.When the pressure from brush is greater than the maximum value set，the process is the same with the above account［6］.

Suppose that the output speed of the motor is 1 800 rpm，gearbox transmission ratio is：iT=30，The reduced of rear wheel’s speed is roundly 60 rpm.To meet the requirements of maximum feed speed，suppose total driven motor efficiency is ηtatal=0.8，motor’s output power：

Fig.5 ControI procedure chart

3.5 Design of body part

Body part comprises wheels，a solar battery board，body and push rod.To save space，guarantee the machine’s stability，the cross section is a trapezoid shape design.Four wheels rotate 360 degrees evenly distributed in the four corners of the body.To save labor，the push rod welding in the body at one end is a telescopic type design.The main role of the body is to maintain stability，placing the power machine，brush，motor etc.Under the premise of meeting the above function，we should reduce the volume of body as much as possible.

4 Conclusions

We designed this removal machine fill the blank of specialized moss removal tool.The equipment working principle is simple，high efficiency of cleaning，convenient popularization and application for the daily cleaning of the moss.However，the device still has some problems in the mechanism and deserves further innovation place.It still cannot achieve true full-automatic cleaning process.So we still need to continue to explore and study，optimize and improve equipment structure.

Acknowledgements

This paper is supported by National Undergraduate Training Programs for Innovation and Entrepreneurship（20141049718007）.

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Hydromechatronics Engineering

http：//jdy.qks.cqut.edu.cn

E-mail：jdygcyw@126.com

半自動化江邊青苔清除機的設計

張慶英*，李 馨，李如舟，喻曉宇
武漢理工大學，武漢 430063

針對目前青苔清除工作須耗費大量人力物力、且現有清除工具簡單低效的情況，設計出一種半自動化江邊青苔清除機。介紹了青苔清除機的結構和工作原理。該設備具有便于使用、節省勞動力、效率高、適用性強等優點，很大程度上解決了現存工具的安全隱患。

半自動化；橫向進給；豎向進給；剪叉機構

10.3969/j.issn.1001-3881.2015.12.005Document code：A

TQ330.4+93

20 December 2014；revised 5 January 2015；accepted 11 March 2015

*Corresponding author：Qing-ying ZHANG，Professor.

E-mail：kathy8899@126.com