Earticle

For motor controller designers, building a simulation environment is not a difficult process. After verifying the controller by simulation, it is common to select 20kHz for the current control loop, 1kHz for the speed loop, and 100Hz for the position loop when implementing the actual HW embedded system. This is because maximized cycles (20kHz) for each control loop are unnecessary in control theory and are a waste of cost and HW resources. However, in a simulation environment, each loop will often have the same control cycle (20kHz maximum). This is because we think it is unnecessary to reflect this part in the simulation. In this paper, it is shown that the difference in the sampling time of each control loop makes a big difference in the simulation result, and as a solution, it is proposed to apply LPF to the position loop output stage. In the process, the reasons for the differences were analyzed, and the effect of LPF, the reason for application, and the feasibility of implementation were proved by actual software coding.

Calculation unit and peripheral units that are used to make the position controller are embedded to one chip FPGA. $\textbullet$ Feed-forward PID controller and interpolator in the calculation unit mitigate frequent context switching. $\textbullet$ The peripheral units reduce the size of the joints position control board. $\textbullet$ Because the calculation unit is designed with pipeline structure, it has the advantages to apply to the multi joints.

Background/Aims: Although an implantable loop recorder (ILR) is a valuable tool for investigation of unexplained syncope, there are limited data regarding time course to diagnosis and predictors of serious arrhythmias as a cause of unexplained syncope. We sought to investigate diagnosis rate by time period after ILR implantation and identify predictors of serious arrhythmias in patients with unexplained syncope. Methods: We identified 394 patients who received ILR implantation for unexplained syncope enrolled in the Korean ILR registry. Results: Serious arrhythmias were documented in 205 patients (52.0%). One hundred seventy-two patients (43.7%) had sick sinus-node syndrome (SSS), 24 (6.1%) had atrioventricular block, and nine (2.3%) had ventricular arrhythmia. Of these, 48 (23.4%) and 77 (37.6%) were diagnosed within two weeks and one month after ILR implantation, respectively. Median time to diagnosis was 62 days. In multivariable analysis, left atrial volume index (LAVI) ≥ 34 mL/m2 (hazard ratio [HR] 1.582), hypertension (HR 1.788), sinus bradycardia with a heartrate less than 60 beats per minute (HR 1.762), and LAVI ≥ 34 mL/m2 combined with sinus bradycardia (HR 1.911) were independent predictors of SSS. Cumulative detection rate of SSS was significantly higher in patients with LAVI ≥ 34 mL/m2 than those with LAVI < 34 mL/m2 (p < 0.001). Conclusions: More than half of patients with unexplained syncope had serious arrhythmias, and more than one-third of these arrhythmias were diagnosed within one month after ILR implantation. LAVI combined with sinus bradycardia may be a useful predictor of SSS as a cause of unexplained syncope.

This paper presents a semi-automatic methodology to synthesize executable digital controller saftware in a multi-loop control system. A digital controller is described by a task graph and end-to-end timing requirements. A task graph denotes the software structure of the controller, and the end-to-end requirements establish timing relationships between external inputs and outputs. Our approach translates the end-to-end requirements into a set of task attributes such as task periods and deadlines using nonlinear optimization techniques. Such attributes are essential for control engineers to implement control programs and schedule them in a control system with limited resources. In current engineering practice, human programmers manually derive those attributes in an ad hoc manner: they often resort to radical over-sampling to safely guarantee the given timing requirements, and thus render the resultant system poorly utilized. After task-specific attributes are derived, the tasks are scheduled on a single CPU and the compiled kernel is synthesized. We illustrate this process with a non-trivial servo motor control system.

Recently, ground source heat pump systems are being used in buildings for cooling and heating to reduce greenhouse gas and save energy. However, ground source heat pump systems mainly use the vertical closed-loop geothermal system design rather than the open-loop geothermal system design. This is due to a lack of knowledge and few research feasibility studies. In this research, a dynamic thermal analysis numerical simulation based on a standard house model was conducted for an open-loop geothermal system. Based on heating load analysis results, the life cycle costs of a standard house using an open two-well geothermal system were analyzed and compared with a vertical closed-loop geothermal system, and a diesel boiler. As a result, it was found that using an open two-well geothermal system shows economic return on investment after three years.