Early on, systems relied on basic start/stop and limit switches, but as processing power and speed have increased, electronic industrial system controls have grown to be the more sophisticated option and become ever more capable.
In the nearly 40 years since electronic control systems first became common features of industrial machines, controls theory has necessarily evolved to keep pace with machine design. Early on, systems relied on basic start/stop and limit switches, with perhaps the added sophistication of two-speed valves. It then became possible to coordinate various parts of the system’s action, with sensors indicating various states; early microprocessors kept track of those states and issued command signals based on programmed instruction sets. As processing power and speed have increased, electronic industrial system controls are growing ever more sophisticated and becoming ever more capable.
Why Energy Transmission Makes a Difference
Electromechanical systems transmit energy to the load with solid material parts like shafts and gears. Therefore, these systems feature near instantaneous on/off capabilities, and controls are essentially unaffected by environmental or system changes, such as temperature. From a controls standpoint, these systems are stiff and linear, meaning control algorithms can be simpler. However, electromechanical systems are challenged by shock or dynamic loading, and experience mechanical wear, resulting in a finite working life before refurbishment or replacement.
Fluid power systems have tremendous power density and are significantly more tolerant of shock loading. That is due to the use of hydraulic fluid as an energy transmission media. When the system is shocked, the hydraulic fluid exhibits compressibility effects and will also transmit forces to the pipes, hoses, and tanks that contain the oil in fluid power systems. Shock distribution does not typically result in permanent damage to a hydraulic system, and the system can continue to operate normally after long periods of shock loading events. As a side note, hydraulic fluid characteristics will exhibit slightly different behaviors depending on changing environmental conditions such as temperature.
Read more: Going Beyond PID in Hydraulic Motion Control