# Controller of Pneumatic Muscles Implemented in Active Seat Suspension
## 1 Introduction
Numerous studies have determined statistical natural vibration frequencies, such as the head at 4 and 25 Hz, upper limbs at 3 Hz, and lower limbs at 5 Hz [31]. These frequencies can vary among individuals, depending on physical parameters. [PERSON] et al. present a methodology for developing a model of a human sitting in a vehicle seat [32]. The work shows how the parameters of the model for a single person are selected experimentally using optimization methods. The vibrations affecting the operator's body result from the interaction of subassemblies characterized by vibrations due to their operating principles, such as the operation of an internal combustion engine or the vehicle moving over uneven terrain. Due to the diverse construction of machines, their work characteristics, and the use of many mechanical subassemblies with different dynamic properties, workers are exposed to long-term vibrations of various acceleration values. In this work, we develop an original controlled vibrosolation system where the active force is generated by two pneumatic muscles. This research focuses on reducing horizontal vibrations along the direction of the working machine's movement, which are transmitted to the human body. To achieve this, we develop a proprietary microcontroller, which is compared with a commercially available device from National Instruments (NI) used in previous studies [30]. Our approach involves using inverse models of the pneumatic muscles to calculate the desired active force and suspension travel, implementing a new hardware solution, and developing a novel signal flow control algorithm. However, the assessment of the propagation of harmful vibrations in the entire body or individual organs of the driver is not the subject of this work. This requires the use of biomechanical (biodynamic) models of the driver's body in simulation studies, such as those presented in [33; 34]. The novelty of this paper includes the following points:  
* The first proposal for the control design of a horizontal seat suspension based on the desired force in an active vibration reduction system and the inverse model of pneumatic muscles as force actuators;
* An original architecture of the microcontroller that controls proportional pressure valves to obtain the desired active force in real-time;
* An experimental investigation of the proposed control policy for random vibrations affecting human operators in typical heavy machinery during their work. The significance of this work lies in its potential to improve the comfort and safety of machinery operators by effectively reducing harmful vibrations through advanced control strategies and innovative microcontroller design. Compared to the system presented in [30], the optimization of the seat suspension design in this work, particularly by replacing the hydraulic shock absorber with pneumatic muscles, simplifies the design and reduces costs without compromising effectiveness. This approach successfully meets the cost-effectiveness criterion by lowering production costs while maintaining system performance. Thus, this paper demonstrates a significant advancement in the application of PAMs for active seat suspension systems, offering a promising solution to a critical problem in industrial and automotive settings.