AIR PRESSURE CONTROL SYSTEM FOR SOFT ROBOT USING SOLENOID VALVE WITH PWM SIGNAL

• Main Author: Fairuziko Nurrajab, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/74782
• Institution: Institut Teknologi Bandung

Soft robot research is currently growing rapidly due to its adaptable and customisable base material. In the medical field, soft robots have more advantages than conventional hard robotics in terms of material safety, similarity to biological structures, and more natural-looking movements. Soft robot has been widely used for medical needs such as bionic hands, finger movement rehabilitation tools, and tools for endoscopy. Although it has many advantages, soft robots have a more complicated motion control system compared to conventional robotics. This is because soft robots cannot create large motion forces due to their soft base material and require more detailed motion performance analysis. Therefore, this research attempts to create a pneumatic-based soft robot motion control system with a PID controller. The target of this research is to produce a stable and linear control system in accordance with the limitations of the components used. The soft robot design is a finger-shaped fibre reinforced type with ECOFLEX 00-30 silicone resin base material. Identification of soft robot characteristics shows that the actuator system is linear and marginally stable in open loop condition between pressure and actuator movement position in separate pressure ranges, 0 - 21 KPa and 21 - 36 KPa pressure. Pressure measurements were made using an MPX5500DP analogue air pressure sensor. The soft robot control system then uses a solenoid valve circuit with pulse width modulation (PWM) signal input. In this research, AIRTAC 2/2 solenoid valve and SMC 3/2 solenoid valve are used. The main principle of the control system is to vary the duty cycle percentage of the PWM signal input within a certain period and see the pressure value coming out of the circuit. In this research, a PWM signal period of 30 ms is used. Using the system identification method, it was found that the AIRTAC 2/2 and SMC 3/2 solenoid valve system used is a second-order system that is linear and marginally stable in open loop conditon. Using the PID Tuner in the MATLAB application, PID values were obtained for experiments that will be implemented on the Arduino MEGA 25. Control system experiments with PID controllers show that the AIRTAC 2/2 solenoid valve system can have a settling time of ±3.2 seconds at a pressure setpoint with a step signal form. Meanwhile, the SMC 3/2 solenoid valve has a settling time of ±3.76 seconds. In addition, the system was also tested using pressure setpoints in the form of sinusoidal and triangular signals for 6 minutes. The experimental results show that the AIRTAC 2/2 solenoid valve system has a maximum error value of 4.19 KPa for sinusoidal signals and 3.18 KPa for triangular signals. Meanwhile, the SMC 3/2 solenoid valve system has a maximum error value of 4.31 KPa for sinusoidal signals and 3.64 KPa for triangular signals. Therefore, in this study, the AIRTAC 2/2 solenoid valve performs better than the SMC 3/2 solenoid valve. After the experiment, it is revealed that the solenoid valve AIRTAC 2/2 and SMC 3/2 also marginally stable in close loop condition.