低频超声测井仪主控系统设计与实现

Design and realization of the main control system for low frequency ultrasonic logging tool

针对低频超声测井仪声波发射、数据采集及数据传输于一体的控制要求,设计了一种基于DSP+FPGA异构控制技术的新型主控系统。该系统使用DSP作为主控制器,通过CAN总线与井下电缆遥传通信,根据接收的指令产生控制时序,使用有限状态机完成工作流程控制,创新性地采用基于加权马氏距离的健康度评估方法评判仪器工作状态。使用FPGA作为从控制器,采用指令数据通道独立控制方法实时转发控制指令,同步声波激发与采集,实时接收声波数据。采用基于自定义并口双口RAM的协同通信机制完成DSP与FPGA之间的数据传输。采用差分传输技术实现与发射系统、采集系统之间的通信。测试表明:该主控系统通信误码率低,控制实时性高,状态评估准确,具备声波发射、数据采集及数据传输一体化控制能力,满足低频超声测井仪控制要求。

A new type of main control system based on DSP+FPGA heterogeneous control technology was designed to meet the control requirements of integrating acoustic wave emission,data acquisition and transmission of low-frequency ultrasonic logging tools.The system used DSP as the main controller,communicated with underground cable through CAN bus,generated control timing according to received instructions,used finite-state machine to complete workflow,and innovatively used a health assessment method based on weighted Mahalanobis distance to evaluate the working status.Using FPGA as the slave controller,the command-data channel independent control method was used to transmit control commands,synchronize acoustic wave excitation and acquisition,and receive data in real-time.Adopting a collaborative communication mechanism based on custom parallel port and dual port RAM to complete data transmission between DSP and FPGA.Using differential transmission to achieve communication with transmission and acquisition system.The test shows that the main control system has a low communication error rate,high real-time control,accurate state assessment,and integrated control capabilities for acoustic wave emission,data acquisition and transmission,meeting the control requirements of low-frequency ultrasonic logging tools.