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TitleSynopsis Hydraulic Arm
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Table of Contents
                            Flexible hydraulic arm is a complicated system which coupled by mechanics and hydraulics. It is widely applied in all kinds of large engineering equipments, such as concrete pump truck, bridge monitor truck, arm frame of crane, etc. The arm system of the hydraulic arm is a multi-body system with redundant freedom, strong nonlinear, coupled with rigid and flexible characters.
So it is of great theoretic value and real engineering significance to study the arm system of the hydraulic arm. In this theme, the movement of flexible hydraulic arm and hydraulic cylinders are separately analyzed with flexible multi-body dynamics, and the mechanical hydraulic dynamic model of the driving system and the arm system is built with Lagrange Equation and Virtual Work Theory. And the dynamic differential equation is built with the driving force of the hydraulic cylinder as the main force.
With the track programming and the optimization method, the dynamic converse problem of the arm end track is researched, so as to get the optimized rotation angle when the arm end reaches the expected point. By using the PD control theory, without decoupling and rank-decreasing, only with feedback from the hydraulic system to realize the close loop control of the arm end position, pose and movement, the relationship between the hydraulic system and the end position & pose is studied, so that the flexible distortion is reduced and the liberation is restrained. What’s more, the simulation model of the mechanical arms is built by the dynamic simulation software. The simulation result proves that the movement equation built by this way can clearly describe each dynamic character of the mechanical arms.
Introduction to fluid power
1.4 Pascal’s Law
2.3 Transmission of forces through liquids
When the end of a solid bar is struck, the main force of the blow is carried straight through the bar to the other end.  This happens because the bar is rigid. The direction of   the   blow   almost   entirely determines the direction of the transmitted force.
	2.3.2 Pressure
	2.4 Atmospheric Pressure and its Effects
2.5 Multiplication of forces
Components used in the fabrication of this project
4.1 Hydraulic syringes
4.1.2 Single acting vs. double acting
Fig. 20
4.2 Fluid  lines  and  fittings
4.4.1 Mechanical gripper
5.1.3 Hinge
                        
Document Text Contents
Page 1

ABSTRACT

Flexible hydraulic arm is a complicated system which coupled by mechanics and
hydraulics. It is widely applied in all kinds of large engineering equipments, such
as concrete pump truck, bridge monitor truck, arm frame of crane, etc. The arm
system of the hydraulic arm is a multi-body system with redundant freedom, strong
nonlinear, coupled with rigid and flexible characters.

So it is of great theoretic value and real engineering significance to study the arm
system of the hydraulic arm. In this theme, the movement of flexible hydraulic arm
and hydraulic cylinders are separately analyzed with flexible multi-body dynamics,
and the mechanical hydraulic dynamic model of the driving system and the arm
system is built with Lagrange Equation and Virtual Work Theory. And the dynamic
differential equation is built with the driving force of the hydraulic cylinder as the
main force.

With the track programming and the optimization method, the dynamic converse
problem of the arm end track is researched, so as to get the optimized rotation
angle when the arm end reaches the expected point. By using the PD control
theory, without decoupling and rank-decreasing, only with feedback from the
hydraulic system to realize the close loop control of the arm end position, pose and
movement, the relationship between the hydraulic system and the end position &
pose is studied, so that the flexible distortion is reduced and the liberation is
restrained. What’s more, the simulation model of the mechanical arms is built by
the dynamic simulation software. The simulation result proves that the movement
equation built by this way can clearly describe each dynamic character of the
mechanical arms.

Page 2

BACKGROUND

The basic concept used behind the operation is PASCAL’s LAW. This law states
that when a pressure is applied at one point of a fluid contained in a constrained
volume, then the pressure due to that force is equally transmitted to all the points
of the fluid, which are acted upon by the same pressure.

Using the same principle, we applied pressure to fluid in syringe which is
transmitted to other end of tube which is connected to a syringe. This
motion of the syringe is used to move the links or parts of the mechanism
which are attached to respective syringes

This hydraulic arm is designed to be a pick and place robot. A hydraulic arm is
powered by fluid under pressure. Hydraulic power is widely used for robots,
especially in situations where lots of power is needed.

The extensive use of hydraulics is to transmit power due to the fact that properly
constructed fluid power systems possess a number of favourable
characteristics. They eliminate the need for complicated systems of gears, cams,
and levers.

Hydraulic robots use pressurized oil or water as the main working power.

HYDRAULIC ARM Page 2

Page 34

flow through the capillary. This time is multiplied by the temperature constant of
the viscometer in use to provide the viscosity, expressed in centistokes.

The following formulas may be used to convert centistokes (cSt units) to
approximate Say bolt universal seconds (SUS units).

For SUS values between 32 and 100

For SUS values greater than 100:

Figure 17— Saybolt viscometer

3.1.1.2 Viscosity Index

The viscosity index of oil is a number that indicates the effect of
temperature changes on the viscosity of the oil. A low viscosity index
signifies relatively large change of viscosity with changes of
temperature. In other words, the oil becomes extremely thin at high
temperatures and extremely hick at low temperatures. On the other hand,
a high viscosity index signifies relatively little change in viscosity over a

HYDRAULIC ARM Page 34

Figure 17.— Saybolt viscometer

Page 67

 Scuba divers must understand this principle. At a depth of 10 meters under

water, pressure is twice the atmospheric pressure at sea level, and increases

by about 100 kPa for each increase of 10 m depth.

CONCLUSION

My design uses extremely simple ideas and mechanisms to achieve a complex set
of actions and is intended to imitate the actions of the operators. However, these
hydraulic arms are expensive for small scale industries. If the major problem of
high initial cost is addressed, a hydraulic arm can be introduced in any industry to
bring in automation. The mechanical links and parts that have been fabricated are
extremely simple.

Hydraulic Arm will-

 Reach the greatest distance to deliver a given object.
 Pick up the heaviest possible object.
 Deliver the most objects in a given amount of time.
 Function in an assembly line.
 Have a system to lift the object it picks up.
 Battle against another arm for an object.
 Rotate as Ill as reach and grab.
 Dig and recover objects.

HYDRAULIC ARM Page 67

http://en.wikipedia.org/wiki/Kilopascal
http://en.wikipedia.org/wiki/Scuba_diving

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