熊利荣, 郑伟, 罗舒豪. 基于触觉感知的家禽净膛机械手及其控制系统的设计[J]. 农业工程学报, 2018, 34(3): 42-48. DOI: 10.11975/j.issn.1002-6819.2018.03.006
    引用本文: 熊利荣, 郑伟, 罗舒豪. 基于触觉感知的家禽净膛机械手及其控制系统的设计[J]. 农业工程学报, 2018, 34(3): 42-48. DOI: 10.11975/j.issn.1002-6819.2018.03.006
    Xiong Lirong, Zheng Wei, Luo Shuhao. Design of poultry eviscerated manipulator and its control system based on tactile perception[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(3): 42-48. DOI: 10.11975/j.issn.1002-6819.2018.03.006
    Citation: Xiong Lirong, Zheng Wei, Luo Shuhao. Design of poultry eviscerated manipulator and its control system based on tactile perception[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(3): 42-48. DOI: 10.11975/j.issn.1002-6819.2018.03.006

    基于触觉感知的家禽净膛机械手及其控制系统的设计

    Design of poultry eviscerated manipulator and its control system based on tactile perception

    • 摘要: 针对机械手净膛过程中家禽内脏易破损的问题,该文设计了基于触觉感知的机械手及其控制系统。利用STM32单片机产生脉冲宽度调制PWM(pulse width modulation)信号控制机械臂在X,Y,Z 轴方向上的运动,同时控制机械手爪步进电机正转,实现机械手爪的闭合。利用单片机的模数转换器ADC(analog-to-digital converter)模块实时采集安装在手指内侧的压阻式薄膜传感器上的压力,将采集的压力值与试验得到的7.7 N压力阈值进行分析比较,控制机械手爪步进电机反转,从而控制机械手爪的抓紧力度,保证内脏不至于受力太大而破损,也不至于闭合不够内脏脱落。利用Qt Creator开发净膛机械手的控制界面,包括点动和自动两种控制模式。试验结果表明:带触觉系统的机械手爪能明显减小内脏的破损,内脏破损平均得分由4.75分减小到4分,且净膛率为87.4%。该机械手的性能稳定、对内脏的破损小、自动化程度高、人机交互界面友好且易控制,可为后续净膛机械手的设计提供参考。

       

      Abstract: Abstract: Aiming at the problem of poultry entrails easy to be damaged in the poultry eviscerated processing, we designed the manipulator and its control system based on tactile perception in this paper. According to the size and depth of abdominal part of broiler with the general size, the maximum distance from the mechanical gripper when it is opened and the length range of the mechanical finger are respectively determined. Through the analysis of the poultry entrails, the bending degree of the mechanical fingers is determined, and then the envelope space when the mechanical gripper is closed is determined. The three-dimensional model of the mechanical gripper is established by SolidWorks software. The size of mechanical gripper is determined by the movement analysis and the assembly of mechanical gripper. The mechanical gripper is driven by a screw, the rotary motion of the stepper motor is converted into a linear motion of the slider by means of a screw, and then through the connecting rod the movement of mechanical fingers is achieved. STM32 single chip microcomputer is used to generate PWM (pulse width modulation) signal to control the move of mechanical arm in X, Y, Z axis direction, and at the same time to control the positive direction rotation of stepping motor of manipulator, achieving the closing of mechanical paw. The piezoresistive film sensor is used as the tactile sensing part of the mechanical gripper. When the pressure on the sensor becomes larger, the resistance value becomes smaller. On the other hand, when the pressure becomes smaller, the resistance value becomes larger. Single chip microcomputer can collect the voltage signal, but can not directly collect the resistance signal, so the resistance-voltage conversion module is used to make the changes of resistance value of the sensor that is caused by the changeable pressure on the sensor, which becomes the corresponding voltage signal. In this way, the ADC (analog-to-digital converter) module of single chip microcomputer is used to collected the pressure of piezoresistive type film sensor in real time installed in the inside of finger. We make the 4 broilers as a group and conduct the visceral pressure threshold test of broiler with a total of 3 groups of broilers and the pressure threshold of the mechanical gripper is determined. We compare the collected pressure with pressure threshold value that is 7.7 N, and control reverse rotation of stepping motor of manipulator, so as to control the force of manipulator paw to ensure that entrails would not endure too much force to be damaged, or would not fall off due to closing not enough. Qt Creator is used to draw the user graphical interface of poultry eviscerated manipulator, and the interface is mainly composed of serial port, display box, automatic mode, manual mode and operation control, and includes manual and automatic control modes. In automatic mode, you can enter the running distance of the 3 axes to determine the movement state of the manipulator, and at the same time, in manual mode, you can click the manual button to control the action of the robot. The PC (personal computer) and STM32 single chip microcomputer are connected by the serial data cable, and then the system is initialized. In this way, you can operate the control interface. In addition, when the manipulator gets trouble in the working process, you can click the stop button to make all the stepper motors disabled, to ensure the safety of equipment. The results of test showed that mechanical paw with the tactile system could significantly reduce the damage of entrails,the average score of visceral damage decreased from 4.75 to 4, and the evisceration rate was 87.4%. The manipulator has the advantages of stable performance, less damage to entrails, high degree of automation, friendly human-computer interface and easy control, and has high practical value.

       

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