Dry Contact Position Actuator and Brake Mechanism Controller Suitable for Heliostat Systems

Thanks to our successfully completed projects supported by the Ministry of Industry and Technology of the Republic of Turkey, versatile gains have been achieved in CSP heliostat technologies, both mechanical, electronic and software based. In the heliostat infrastructure developed in this context, a long-lasting and field-resistant mechanical structure that can guide the mirror surface up to 12 m² with high precision by integrating linear actuator-based drive mechanisms without backlash, 60:1 ratio slew drive systems, dual-axis inclinometer, hall sensors and feedback structure supported by high-resolution optical encoders that provide accuracy below 1± mrad in the azimuth and elevation axes, and thanks to its robust torque tube structure, a long-lasting and field-resistant mechanical design has been revealed. This mechanical system is supported by control devices with IP65 protection class and in accordance with IPC-2221B, EN 60204-1 and RoHS standards; Critical safety functions such as electrical isolation, short circuit, overcurrent, overvoltage, reverse polarity and thermal protection are provided in the devices. Multi-mode control loops (Reflect tower, reflect sun, Stow, Idle) were applied by running real-time solar position algorithms (SPA) on the ARM Cortex-M4-based microcontroller with 84 MHz processing power, and azimuth and elevation angle errors were reduced to 0.0024° and 0.0028°, respectively. BLDC motor drivers developed in parallel operated with <50W power consumption in a wide supply range of 24–48V DC thanks to their completely hardware-based structure; sudden braking, active torque limit, overcurrent/voltage and thermal protection features have been gained, and it has been confirmed that the MTBF value exceeds 390,000 hours in accelerated life tests. On the software side, performance software has been developed that can detect optical aberration below 1 mrad in different weather conditions and works with Gaussian-based filtering, adaptive thresholding and edge detection algorithms; Integrated with RS485 communication controllers, this system has been tested on more than 10,000 images, ensuring fast, cost-effective and reliable field calibrations. In addition, thanks to the automatic target deviation calculation and offset transfer functions of the software, instant calibration in the field is made possible, and long-term stable operation is verified with low memory usage. A high-precision opto-mechanical design, low-power but high-reliability motor drive hardware, and image processing-based performance measurement software have been combined to create an integrated technology infrastructure that enables CSP heliostats to operate with long-life, high efficiency, low cost, and minimal maintenance.