1.2 Problem Statement
Pneumatic system is extensively used in the industrial environment mainly for simple repetitive tasks due to their compactness, power to weight ration and simplicity. The use of
pneumatic muscle technology has spread into many different fields including robotics, human power assisted robot exoskeleton and mobility assistance, therapy and rehabilitation. Besides
that, to define an accurate mathematical modeling to represent the PMA system dynamics is a difficult task as well. The main scopes of this project will mainly focus in the experimental
setup and mathematical modeling of the dynamic system. The experimental and simulation results will be used in the performance validation.
Motivation
: - The use of pneumatic muscle technology has spread into many different fields including robotics, human power and mobility assistance, therapy and rehabilitation. The
design and development of this project will help in the research of applicabilityeffectiveness of pneumatic muscle actuator positioning system in robotics applications; especially for a set-
up with very non-linear characteristics and very difficult to be controlled.
1.3 Objective of Project
1. To develop the pneumatic muscle actuator system and model its dynamic system. 2. To validate the effectiveness of the proposed modeling in positioning control via
experimental and simulation.
1.4 Scope of Project
In order to achieve the objective of the project, several scopes have been outlined:- Necessary, research on the field of pneumatic muscle actuator will be done at first.
An accurate mathematical modeling to present the dynamic behavior of the pneumatic muscle actuator will proposed.
An experimental setup with effective position control setup will be designed and developed.
The pressure range for the PMA experimentation were set to 0-6barmax and maximum load tested were 65kg.
The resolution of infrared sensor was 0.01 Volts per step from ADC. The effectiveness of the proposed mathematical modeling will be validated via
experiment and simulation result. A brief conclusion of the effectiveness of the system and the adaptability of PMA into
industrial application will be presented.
CHAPTER 2
LITERATURE REVIEW
2.1 Pneumatic Muscle Background
2.1.1 Description of pneumatic muscle
A pneumatic muscle actuator PMA is a mechanical apparatus that copies the conduct of skeletal muscle where it contracts and creates drive in a nonlinear way when activated [1].
PMAs could be found in common elastic tube, wrapped inside man-made mesh, for example Kevlar, at predetermined angle. Defensive elastic covering encompasses the fibber wrapping
and fitting metal fittings are connected at every close [2]. The filament wrapping gives uphold and upgrades incitation. PMA is an actuator which changes over pneumatic or water driven
vigor into mechanical structure by exchanging the force connected on the internal surface of its bladder into shortening tension. When the PMA is pressurized, the hose expands in its
peripheral direction, thus generating a tensile force and a contraction motion of muscle longitudinal direction. The level of contraction and constrain preparation is reliant on the
pulling constrain against the PMA load. Figure 2.1 represents the operation of a PMA and Figure 2.2 shows the Festo fluidic muscle.
Figure 2.1: Illustration of pneumatic muscle operation [2]
Figure 2.2: Commercially used PMA Festo fluidic muscle [11]. This type of actuator has several unique characteristics, some of its characteristics
which have made it as an ideal actuator for applications involving human interaction. Pneumatic muscles are capable of producing a high force output. They have higher
powerweight and powervolume ratios about 1 Wg and 1Wcm
3
than electric motors or hydraulic actuators [3]. They have a higher force output than a pneumatic cylinder of equal
volume [4]. Pneumatic muscles are cost effective, clean, highly dynamic movements, no slip effect; intermediate positions can be set easily by regulating the pressure, compact, and can be
used in harsh environments because they do not have moving parts such as pistons or guiding rods [5]. There are also a safe alternative to other actuators. The main disadvantage of this
actuator is that its motion is difficult to be controlled due to its nonlinear characteristics. This is due to the need of controlling the both PMA displacement and PMA force by only varying
the inlet pressure to the muscle actuator.
2.2 Types of pneumatic muscle
There are many types of artificial muscle actuator in the field of research. Figure 2.3 shows the picture of the famous muscle actuators and the names are listed below:-
i. McKibben Muscle ii. Braided Muscles
iii. Sleeved Bladder Muscle iv. Pleated PAM
v. Netted Muscles vi. Yarlott Muscle
vii. ROMAC viii. Paynter Hyperboloid Muscle
Figure 2.3: a McKibben MuscleBraided Muscle, b Pleated Muscle, c Yarlott Muscle, d Robotic Muscle Actuator ROMAC Muscle and Paynter Hyperboloid Muscle [2].
2.3 Pneumatic Muscle Operation Methods
The basic principles of the PMA‟s operation can be categorized in two cases:
i Under a constant load and with varying gauge pressure.
ii Under a constant gauge pressure and a varying load.
To illustrate this operation a PMA operations a standard and dynamic configuration has to be prepared. Figure 2.4 one illustrates the PMA configuration in real world, one end of
the PMA is fixed and the other end is loaded with constant mass. During this type of operation the PMA:
i The PMA will shorten its length by increasing its enclosed volume, and
ii It will contract against a constant load if the pneumatic pressure is increased.
Figure 2.4: PMA operation at constant load [2]. The second type of PMA‟s operation, which is the case of operation under constant
gauge pressure, is illustrated in Figure 2.5. During this type of operations the PMA: i
At constant pressure the PMA will decrease its length when the load is removed, and
ii Its contraction has an upper limitmaximum contraction at which it develops no
force and its internal bladder volume is at maximum level.
Figure 2.5: PMA operation at constant pressure [2]. For these two principal operations, for given pressure and load, the PMA has an
equilibrium length. This characteristic makes pneumatic muscle actuator unique from pneumatic cylinder where the developed actuation force depends on only the pressure and the
piston surface.
2.4 History of Pneumatic Muscle
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