Digital proportional-derivative controller implemented in low-resource microcontrollers

The use of software and microcontrollers helps engineering students to gain a better understanding of the different concepts and algorithms of digital control theory, which they can apply in their professional work in industrial environments. Typically, these digital control concepts and algorithms are implemented in high-resources microcontrollers; nevertheless, we show that they can also be implemented in low-resource devices, helping students to acquire fundamental knowledge and develop long-term skills to solve real problems from the learning they achieve in their undergraduate educational programs in control or computer engineering. For this purpose, we provide an algorithm to synthesize a digital proportional-derivative controller oriented to low-resource microcontrollers (microcontrollers without floating-point unit). This algorithm allows implementing solutions for classic controllers in low-resource microcontrollers applied to academic and technological fields. This algorithm reduces the excessive amount of execution time in a low-resource microcontroller, it works with integer numbers and it is designed to implement fast classical controllers, which typically are performed with floating-point operations. Furthermore, we present a brief description of the implemented electronic circuit, serving as a guide for students to develop their own circuits. The experimental results show that the proposed algorithm can be successfully applied to an electromagnetic levitation system, which is commonly used in the academic training of electronics and control engineers, mainly due to its unstable nature. In this case, although the levitation system has a small time constant, the proposed algorithm appropriately leads the system to a stable regime.