奶牛饲喂自动机电控制系统的设计与试验

为开展奶牛精准饲喂及采食行为学研究,设计了一种集自动识别、饲喂、数据自动采集、数据分析与处理于一体的奶牛饲喂自动机电控制系统。该系统包括机械装置、电子识别系统、料槽称质量系统、中央控制系统、现场数据存贮及远程数据提取与分析系统等几部分。其中,机械装置包括料斗、支撑座、栏杆和阻挡单元等;电子识别系统包括阅读天线及料门启闭的气动装置;料槽称质量系统除支撑座外,还有嵌入的质量传感器及线路;中央控制系统包括微处理器、看门狗复位电路、读卡器电路、称质量数据采集电路、数据通信电路、数据收发器电路及外围驱动与稳压电路等。现场数据存贮电路接受来自各个饲喂系统的中央控制系统发送的采食行为数据,其主板结构与中央控制系统基本一致,预设可存贮记录数为14 000条,且采用堆栈数据存贮模式。远程PC端数据提取与分析系统实时管理采食行为数据,并提供多功能的数据挖掘分析。系统测试结果表明,对牛只低频RFID(134 kHz)电子耳标的识读率为100%,料及槽的计量范围为0.01~200 kg,最低称量精度10 g,实际称量相对误差≤0.15%,同时满足奶牛对最大采食量及精准饲喂对计量的需求。系统的采食行为试验表明,奶牛的日均采食次数、采食时间及采食量等采食行为均差异显著(P0.05),符合奶牛的采食行为特点。具体地,奶牛日均采食次数10~13次,日均采食时间5.38 h,而奶牛个体实际采食量与NRC(National Research Council)模型预测的采食量有-4.76%~7.83%的偏差,可能是由各种内外部因素及NRC模型的普适度造成的,有待进一步研究。总之,该系统能较好地实现奶牛个体的精细化饲喂,为研究奶牛的采食行为特点提供了在线、智能化的自动数据采集与分析平台。

Design and test of electromechanical control system of automatic feeder for dairy cow

In order to perform the studies on the precision feeding and behavioral monitoring of dairy cows, an automatic feeder of dairy cows was designed, which accomplished the functions of cows automatic identification, automatic feeding data (feed intake time and amount) acquisition and data analysis simultaneously. The automatic feeder was composed of mechanical device system, electric identification system, weighing system, central control system, live data collection and storage system, and remote feeding data extraction and analysis system. The mechanical device system was constituted of feeding bin, brackets, railing and blocking apron. The electric identification system included reading antenna and pneumatic switch for discharging. The weighting system was made up of brackets and embedded weight sensor (L6G, technical parameters: Weighing range≤ 200 kg, error less than 0.002 kg). Central control system was composed of microprocessor (LPC1766, technical parameters: Operating temperature of from -40 to 105℃ ;operating voltage of 2.0-3.6 V; flash memory of 256 K, low power consumption), watchdog reset circuit, card reader circuit, weighing data collection circuit, data communication circuit, data transceiver circuit, and external regulator circuit. The reader circuit adopted multi-channel R232 interface and chips (Model: MAX232E), and low-pass filter and 24 bit conversion chip (Model: ADS1232, Dezhou) were used in the weighing data collection circuit. For transceiver circuit, according to the standard ISO 11898, the universal CAN (controller area network) transceiver chip (Model: CTM8251A) with isolation function was adopted, which had 110 nodes at the most and the transmission rate increased to 1 M/s. The ferroelectric memory and serial peripheral interface were adopted in the circuit of data caching system, and the cable data transmission rate could reach 15 MB/s. The live data collection and storage system received signals from the central control system in each feeder, the preset record number in storage system could reach 14000, and the form of stack data was applied in system. The feeding data could be managed and analyzed in real time by data process system in PC (personal computer) terminal. The feeding experiment showed that the cognition rate for low frequency RFID (radio frequency identification) (134 kHz) ear tag by the automatic feeder reached 100%, the range of weighing was 0.01-200 kg, the precise was 10 g, and the weighting error was below 0.15%, which could meet the requirement of cows' precise feeding intake record. The performance test of control system showed that individual cow's feeding behaviors, including feeding frequency, intake time, and feed intake, were different significantly (P<0.05). The average feeding frequency was 10-13 times per day, and the average intake time was 5.38 h per day, which were consistent with cow feeding characteristics. However, the deviation between average daily feed intake and predicted intake value by NRC (National Research Council) model was –4.76%-7.83%, which may be caused by the low applicability of NRC model. In conclusion, the automatic feeder developed in our study can meet the requirement of precise feeding in cows' production, and supply an online and intelligent data automatic record and analysis platform for cow feeding behavior research.