Duc M. Tran

For the design, implementation, performance optimization, and predictive maintenance of high-speed real-time control systems with sub-millisecond control periods, the capability to acquire large volumes of high-rate control data in real time is required without interfering with normal control operation that is repeatedly executed in each extremely short control cycle. In this study, we propose a control-data acquisition method for high-speed real-time control systems with sub-millisecond control periods, in which control data are transferred to an external host device via Ethernet in real time. To enable the transmission of high-rate control data without disturbing the real-time control operation, a multicore microcontroller unit (MCU) is adopted, where the control task and the data transmission task are executed on separately assigned central processing unit (CPU) cores. Furthermore, by applying a double-buffering algorithm, continuous Ethernet communication without intermediate waiting time is achieved, resulting in a substantial improvement in transmission throughput. Using a control card based on TI’s multicore MCU TMS320F28388D, which consists of dual digital signal processor cores and one connectivity manager (CM) core, the proposed control-data acquisition method is implemented and an actual experimental environment is constructed. Experimental results show that the double-buffering transmission achieves a maximum throughput of 94.2 Mbps on a 100 Mbps Fast Ethernet link, providing a 38.5% improvement over the single-buffering case and verifying the high performance and efficiency of the proposed data acquisition method.

In this study, we propose an implementation method of the Encoder Data (EnDat) interface master for slave encoders using only a configurable logic block (CLB) and a serial peripheral interface (SPI) integrated into microcontroller units. By programming the CLB device to execute logic functions and finite state machines designed for the EnDat interface master operation, we realize the EnDat and SPI clocks that are required for the EnDat interface master operation. This approach is cost-efficient because additional hardware components, such as a field-programmable gate array or a complex programmable logic device, are unnecessary for the master implementation. We build a one-axis feed drive system that is powered by an AC motor and equipped with an EnDat linear encoder for measuring table speed and position. By performing various experiments for table position and speed control based on the built feed drive system, we verify the performance and practical usefulness of the implemented EnDat interface master. The maximum EnDat clock frequency without the propagation delay compensation is achieved by 2 MHz, which can cope with 16 kHz control cycle frequency. The usefulness is demonstrated by showing the table speed and position control performance that are acceptable in real applications.

본 논문에서는 낮은 전력 소모 및 다양한 통신 장치를 지원하는 TI 사의 AM3352 microprocessor unit을 기반으로 산업용 임베디드 제어 시스템을 위한 System-on-Module(SoM)을 개발한다. SoM 기반 시스템은 요구되는 입출력 베이스 보드만을 설계하여 시스템을 완성할 수 있기 때문에 개발 기간과 비용을 줄일 수 있고 확장성 및 유연성이 단일 보드 시스템보다 우수한 장점이 있다. 다양한 반도체 소자, 커넥터, SD 카드 소켓을 장착함에도 8.6 cm × 5.5 cm 크기의 소형으로 설계하고 UART, Ethernet, I2C, SPI, 7개의 아날로그 입력, USB를 베이스 보드에 지원하여 활용도를 극대화한다. 산업용으로 사용할 수 있도록 RT Linux를 이식하여 실시간 응용프로그램 개발 환경을 구축한다. UART, Ethernet, I2C, SPI 장치를 동작시키는 Linux 응용프로그램을 작성 또는 활용하고 실험을 수행하여 Linux 운영체제 및 각 입출력 장치의 정상 동작을 검증한다.

The MCU is the core component of the motor drive because the optimized control algorithm is implemented using the MCU. Monitoring motor control variables becomes important because it provides better insights and information to analyze and optimize the performance of the control algorithms. MicroSD card, with its advantages of compact size, interface connection, and reasonable price on acceptable performance, is used as an external storage device. However, the microSD card has a serious disadvantage of its extended busy time in the writing procedure, which affects motor control performance. In this study, we propose a microSD card writing scheme by exploiting the dual-core structure of MCUs to overcome the microSD card busy time and implement a data logger based on the proposed algorithm. The experimental results show that the proposed scheme provides remarkable performance and the capability to log data over a long period without any missing or corrupted data.

In this study, we propose a real-time data storage method to store the high-frequency motor control data of AC servo motor drives. The Micro Secure Digital Card (MSDC) is chosen as the storage device because of its cost-effectiveness and space efficiency. However, the MSDC has a fatal drawback of lengthy write time, which is solved by applying a double-buffering algorithm and distributing the MSDC writing load based on the multi-core architecture of the microcontroller unit (MCU). The proposed data storage method is implemented using a commercial AC motor drive system with an MCU integrating two digital signal processor (DSP) cores and an MSDC socket. From experimental results, it is demonstrated that the proposed method achieves a remarkable MSDC writing speed of approximately 2.44 Mbps, which is sufficient for real-time storage of critical motor control data at fast 10 kHz motor control cycles. Consequently, the proposed method can be used for motor drive optimizations and applications requiring a vast amount of motor control data storage.

Encoder interfaces should be operated in real time with high precision and fast processing for industrial motor control systems. The continuous bidirectional serial synchronous (BiSS-C) interface is an open-source serial communication protocol designed for motor encoders and is suitable for industrial purposes because of its fast serial communication speed. In this study, we propose a method for developing a BiSS-C interface master for a motor encoder slave, using only the configurable logic block (CLB) peripheral integrated into TI microcontroller units. By analyzing the detailed operation protocol of the BiSS-C interface, we create the truth and state tables for logic circuits and finite state machines, which are required for the BiSS-C interface master. Then, by programming the CLB based on the created truth and state tables, we implement the master clock, serial peripheral interface (SPI) clock, and operational process for the master. This approach is cost-efficient because additional hardware components, such as a field-programmable gate array or a complex programmable logic device, are not required for the master implementations. The developed method can be immediately applied to developing the masters for other BiSS-C encoders with different specifications, which is certainly necessary for a motor drive development and test. By building an AC motor control system with the developed master and performing various experiments, we verify the performance and practical usefulness of the developed BiSS-C interface master. The maximum master clock frequency without any CRC errors is achieved by 6.25 MHz, which can cope with more than 20 kHz motor control cycle frequency. The usefulness is demonstrated by showing the motor speed and position control performance that are acceptable in real applications.

Cooperative navigation for fleets of robots conventionally adopts algorithms based on Reynolds's flocking rules, which usually use a weighted sum of vectors for calculating the velocity from behavioral velocity vectors with corresponding fixed weights. Although optimal values of the weighting coefficients giving good performance can be found through many experiments for each particular scenario, the overall performance could not be guaranteed due to unexpected conditions not covered in experiments. This paper proposes a novel control scheme for a swarm of Unmanned Aerial Vehicles (UAVs) that also employs the original Reynolds rules but adopts an adaptive weight allocation mechanism based on the current context than being fixed at the beginning. The simulation results show that our proposed scheme has better performance than the conventional Reynolds-based ones in terms of the flock compactness and the reduction in the number of crashed swarm members due to collisions. The analytical results of behavioral rules’ impact also validate the proposed weighting mechanism's effectiveness leading to improved performance.