Abstract:
Robots, ranging from industrial pick-and-place robots to humanoid robots, are increasingly
being employed to accomplish activities that humans find tiresome and challenging.
Conventionally, they are driven by rotating servomechanism and hydraulic methods.
However, nowadays an alternative actuator with compliant behavior, muscle-like
properties, and extremely low weights is required for some applications, particularly for
medical applications. An interesting alternative to electric actuators for medical purposes
is a Pneumatic Artificial Muscles (PAM) actuator. PAM Actuators have a broad application
prospect in soft robotics. Nevertheless, PAM has highly nonlinear properties among force,
displacement, and pressure, which makes precise position control impossible in the
classical fixed gain PID controller which ignores the important phenomena of
nonlinearities of pneumatic artificial muscle (PAM) manipulator. It also behaves poorly
when operational conditions or environmental parameters change or are unpredictable.
Hence, in this thesis, a Self-Tunning Fuzzy PID controller for position trajectory tracking
of a two-degree of freedom (2-DOF) Pneumatic Artificial Muscle (PAM) Manipulator is
designed enhance the performance of Fixed gain PID controller by adding a fuzzy logic
controller which can handle the nonlinearities. The designed fuzzy-PID controller
immediately modifies the PID gains in response to the error. The Genetic algorithm
optimization technique is used to tune PID gains which are used as initial values of Fuzzy-PID controller and knowledge base for the FLC.
The simulation is carried out using MATLAB/Simulink software. According to the
simulation result, the Fuzzy-PID controller decreases the overshoot by 6.5% for joint one
and by 1.8% for joint two; Similarly, the rise time decreases by 0.0981sec for joint one and
decreased by 0.0757 for joint two, the settling time is also decreased by 0.8851sec for joint
one and decreased by 1.443sec for joint two, when compared with PID controller. We
noticed from the simulation result; the fuzzy-PID controller have a good transient
performance, handle nonlinearities; and reject the disturbance and parameter variation.
Keywords: PID, PAM, GA-PID, Fuzzy-PID, 2-DOF, Nonlinear PID, muscle-like
properties