Robotic Manipulator Arm
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Joined: Sep 2010
24-12-2010, 04:24 PM
Hydraulic Robotic Arm.pptx (Size: 377.8 KB / Downloads: 223)
The Robotic Manipulator Arm extends the flexibility of workstations by transporting material more efficiently and quickly between worktable, peripheral devices and assembly lines etc.
A sub class of more general family of Robots, the Industrial Robots
An industrial robot is officially defined by ISO as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes.
Despite its numerous possible usages, it finds most widespread usage in manufacturing industry.
Typical applications of robots include welding, painting, assembly, pick and place, packaging and palletizing, product inspection, and testing, all accomplished with high endurance, speed, and precision.
Components of Hydraulic Actuation Systems
The fluid used is 40W oil reads as 40 weight oil. It has high viscosity which maintains a lubricating film between moving parts. This also reduces friction loss and cools the components.
Pipe and tubes along with the fittings or connectors, constitute the conducting lines that carry hydraulic fluid between components.
The pump used here is gear pump. A gear pump develops flow by carrying fluid between the teeth of two meshed gears. One gear is driven by the drive shaft and turns the other, which is free. The pumping chambers formed between the gear teeth are enclosed by the pump housing and the side plates. A low pressure region is created at the inlet as the gear teeth separate.
Robotic Manipulator Arm.pdf (Size: 1.05 MB / Downloads: 281)
Hydraulic Actuators employs hydraulic pressure to drive an output member. These are used where high speed and large forces are required. The fluid used in hydraulic actuator is highly incompressible so that pressure applied can be transmitted instantaneously to the member attached to it. A robotic arm incorporates an articulate system, which together function in much same way as its biological counterpart. The skeleton is composed of rigid links that connect varying numbers of joints that are capable of sliding, twisting or rotating. The robot's muscles come in the form of actuators that convert hydraulic, electrical or pneumatic energy into power for each joint. Next there is an electronic nervous system of wires and sensors that carries commands to the muscles of the robotic arm and then back to an external computer. The main difference between the arm of the robot and that of a human is found at the arm's extremity. Rather than having a flexible, multi-fingered hand, typical robot arms end in special-purpose devices called end-effectors, which are installed directly into the wrist. To reduce the number of calculations, needed to determine the robot's exact position, the base is generally kept stationary. In a few applications, however, like the robots in spot welding, robots are programmed to follow an assembly line. The motions of the robots can be programmed by means of direct teaching where the arm is manually guided through its desired motion and the robot's computer remembers these specific motions, sort of like a watch and learn method. Robots can also be taught by means of programming by a computer specialist. Finally there is always the option of creating a learning computer that will gather data as it makes mistakes and on the following attempt, it won't make the same mistake again.
Principle Used in Hydraulic Actuator System
Pressure applied to a confined fluid at any point is transmitted undiminished and equally throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces.
Amplification of Force
Since pressure P applied on an area A gives rise to a force F, given as, F = P×A Thus, if a force is applied over a small area to cause a pressure P in a confined fluid, the force generated on a larger area can be made many times larger than the applied force that crated the pressure. This principle is used in various hydraulic devices to such hydraulic press to generate very high forces.
Advantages of Hydraulic Actuation Systems
Hydraulics refers to the means and mechanisms of transmitting power through liquids. The original power source for the hydraulic system is a prime mover such as an electric motor which drives the pump. However, the mechanical equipment cannot be coupled directly to the prime mover because the required control over the motion, necessary for industrial operations cannot be achieved. In terms of these Hydraulic Actuation Systems offer unique advantages, as given below.
Variable Speed and Direction: Most large electric motors run at adjustable, but constant speeds.It is also the case for engines. The actuator (linear here) of a hydraulic system, however, can be driven at speeds that vary by large amounts and fast, by varying the pump delivery or using a flow control valve. In addition, a hydraulic actuator can be reversed instantly while in full motion without damage. This is not possible for most other prime movers.
Power-to-weight ratio: Hydraulic components, because of their high speed and pressure capabilities, can provide high power output with vary small weight and size, in comparison to electric system components. Note that in electric components, the size of equipment is mostly limited by the magnetic saturation limit of the iron.
Stall Condition and Overload Protection: A hydraulic actuator can be stalled without damage when overloaded, and will start up immediately when the load is reduced. The pressure relief valve in a hydraulic system protects it from overload damage. During stall, or when the load pressure exceeds the valve setting, pump delivery is directed to tank with definite limits to torque or force output. The only loss encountered is in terms of pump energy. On the contrary, stalling an electric motor is likely to cause damage.
Components of Hydraulic Actuation Systems
Hydraulic fluid is essentially non-compressible to be able to transmit power instantaneously from one part of the system to another. At the same time, it lubricates the moving parts to reduce friction loss and cool the components so that the heat generated does not lead to fire hazards. It also helps in removing the contaminants to filter. The other desirable property of oil is its lubricating ability. Finally, often, the fluid also acts as a seal against leakage inside a hydraulic component. The degree of closeness of the mechanical fit and the oil viscosity determines leakage rate. Figure 2 below shows the role played by hydraulic fluid films in lubrication and sealing. The fluid used is 40W oil reads as 40 weight oil. It has high viscosity which maintains a lubricating film between moving parts.
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Joined: Sep 2010
28-12-2010, 02:40 PM
ROBOTIC ARM.pptx (Size: 3.98 MB / Downloads: 187)
To design a robotic arm controlled through the internet/LAN used for patient operation.
To interface the robotic arm and the other components like LCD,DC motor and RF video camera with the microcontroller.
India is a developing country. One of the hurdles it has overcome is medical field.
There is lack of basic medical facilities in cities as well as small towns.
The problems faced by patients are the lack of good facilities and also absence of skilled surgeons.
Incorporation of the robotic arm tackles these problems.
The plus point is the robotic arm is controlled by LAN.
By this method the doctors sitting in any place of the world can perform the surgery on patients and also can know the recovery status.
The choice of using the robots is b’coz they can perform variety of functions in more flexible environment and at lower production costs.
The word robot originated from the Czech word ”ROBOTA” meaning “work”.
Generally a robot is a re-programmable multi-functional manipulator designed to move materials.
The idea behind the development of the robotic mechanism was the hospital visit where the problem faced was the absence of the surgeon.
As we all know that surgery is a common thing these days’ even a small tumor removal needs surgery.
Suppose that the surgeon is in a foreign country to ask him to come over for the surgery is impractical in cases of emergency.
These problems are tackled by our Robotic arm which is fully automated.
Microcontroller provides a helping hand in making a system automatic.
Microcontroller AT89s52 was chosen for a simple reason that it is advanced and more flexible version of microcontroller 8051.
The first robotic surgery was performed in 1992-93 called as the RoboDoc system.
Later the AESOP systems were developed that were used in general surgery.
After commercialization the systems were used in neuro surgery.
After the redesigning process the Da Vinci surgical system was developed.
First robotic surgery was performed in 1997
The surgery using robotics was limited to short distances cos of latency.
The problems that can be tackled by the design of our project and implimentation are:
Lack of proper medical facilities in small towns and cities.
Unavailability of surgeons in time of emergencies.
Sophisticated data acquisition and monitoring techniques.
Centralized robotic arm control.
Presently the problems faced by many hospitals are:
There were situations where the surgeons were unable to be on time for the operation, which could be fatal in many cases.
In many cases patients were shifted abroad in cases of emergency which was impractical.
Here the robotic arm is controlled by the AT89s52.We control the arm through the LAN.
Goals of the project and implimentation
The points to be kept in mind during the control of arm through LAN are:
Strengthen the medical field.
Eliminate the shortage of skilled surgeons.
Scope of the project and implimentation
It counters the problem of unavailability of skilled doctors.
Our project and implimentation is economical.
It is a boon to medical field.
The accuracy and performance is very high.
The system’s services, goals and constraints are established by communicating with the client.
Before the design process begins we communicate with the client and note down the system specifications.
We partition the process into two stages
We represent the system’s function in a form transformable to an executable program.
The individual hardware units and programs are tested.
They are then integrated and tested as a complete system.
The front end application will send the controlling data to the particular computer by sending corresponding IP address.
After sending the commands the Ethernet adapter which is already configured with that particular IP address; will receive the data.
And the Ethernet adapter will send the received data to microcontroller through serial port.
After receiving the command the microcontroller will control the robotic arm by sending appropriate signals to geared motor.
The microcontroller part which is connected in robot side, is doing all the operations of motor control.
The Ethernet card is a medium, which is used to convert LAN signal in to RS232 form.
According to the command received the microcontroller will control the robotic arm step movements.
We use the RF camera’s to view the patient status and transmit it to the PC.
In this project and implimentation we are using the arm only to cut the skin of the patient using the high-speed blades.
Power supply 5v DC - lm 7805
Video camera - RF
Microcontroller - 89s52atmel
Crystal - 11.0592mhz
MAX232 - serial comm.
Buzzer - freq-1 to 18KHZ
LCD - 2x16 characters
The AT89S52 is a low-power, high-performance CMOS.
Compatible with MCS-51 products
8K bytes of in-system programmable (ISP) flash memory
Endurance: 1000 write/erase cycles
4.0V to 5.5V operating range
Fully static operation: 0 Hz to 33Hz
Three-level program memory lock
256 x 8-bit internal RAM
32 programmable I/O lines
Three 16-bit timer/counters
Eight interrupt sources
Full duplex UART serial channel
Low-power idle and power-down mode
Interrupt recovery from power-down mode
Dual data pointer
Is the reset pin. A high on this pin for two machine cycle while the oscillator is running resets the device
Address Latch Enable is an output pulse for latching the low byte of address during the external memory access.
It acts as an Program Pulse Input during Flash Programming.
Program Store Enable is the read strobe to external program memory.
External Access Enable must be strapped to the Gnd in order to fetch the code from external memory.
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
Output from the inverting oscillator amplifier.
Special Function Registers(SFR’s)
Timer 2 Registers
Control and status bits are contained in registers T2CON and T2MOD for timer 2.
The register pair (RCAP2H, RCAP2L)are the capture/reload registers for timer 2 in 16-bit capture mode or 16-bit auto-reload mode.
The individual interrupt enable bits are in the IE register. Two priorities can be set for each of the six interrupt sources in the IP register.
ROBOTIC ARM.ppt (Size: 6.73 MB / Downloads: 252)
To make an autonomous ROBOTIC ARM using microcontroller and motors
To increase the production speed in the industry
To reduce the complexity in manufacturing processes
To increase the profit and productivity in the industries
To move hazardous materials
The manufacturing process are done manually by humans like pick and place
Welding, material handling, and thermal spraying, painting and drilling are doing with the help of machines.
The manufacturing process is automated using ROBOTIC ARM technology
Drilling, milling process are made to simpler by using ROBOTIC ARM
The main idea behind the robotic arm is that it imitates the actions of a human arm or hand.
It is a programmable Robotic Manipulator.
This type of robot is often termed, Anthropomorphic because of the similarities between its structure and the human arm.
The AT89C51 microcontroller is used as the main part of the design
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM).
Atmel AT89C51 is a power full, highly flexible and cost effective solution to many embedded control applications.
Joined: Apr 2012
25-04-2012, 11:20 AM
Robot Manipulators.pdf (Size: 1,000.72 KB / Downloads: 49)
This section provides an initial analysis of the requirements for
a system to perform teleoperated ball catching. A design for
the system is developed from the analysis of requirements, and
Digital Object Identifier the performance of the design is verified by simulation.
The main type of experiments that we want to perform involve
catching a ball thrown across a room. We anticipate a slow
underhand throw from a distance of approximately 5 m. In an
indoor environment, a ball can be thrown with a reasonable
accuracy along a parabolic path with an apex of 2.3 m, with
both the thrower and the catcher situated at a height of 1 m, as
in Simple studies of human performance indicate that
the system must be able to accommodate variations in accuracy
corresponding to catching the ball within a 60360 cm2
window. From these requirements, we can compute flight time
and velocities for the scenario, as summarized later:
One desired feature is to use standard video cameras for trajectory
estimation. With 50-Hz cameras, the frame time is
approximately 20 ms, and a similar time window is expected to
be needed for segmentation and position estimation. In addition,
at least three frames are required for trajectory estimation,
but limited camera accuracy will mean that more possibly, as
many as ten images might be necessary . Thus, the time
delay for the initiation of a throw to the initial trajectory estimate
might be 200 ms. We also intend to do teleoperated
catching, where a human operator controls the robot, so we
have to allow for the operator’s reaction time. This might be
around 100 ms, so 300 ms is reserved for the initial reaction to
a throw, leaving 500 ms for the arm to move into position. In
the worst-case scenario, the arm has to move against gravity
from one opposing corner of the operational window to
another, a distance of 0.9 m. Since the initial experiments will
not be concerned with grasping, a passive bucket-type end
effector will be employed, and the positioning error must be
smaller than the radius of the bucket, preferably less than 1 cm.
Apart from the automated ball-catching task described in the
‘‘Experimental Setup’’ subsection, the manipulator has also
been successfully applied to other tasks, such as teleoperated
ball catching, robot control using a Wiimote video-game controller,
and positioning visual targets used for automated
camera calibration. Since the platform was designed for a
task requiring high velocities, it has adequate performance
for tasks that require lower velocities as well. The strength of
the setup has shown to be the ease with which it can be
applied to new tasks, given a completely open interface. An
obvious weakness is the high power consumption, making it
unsuitable for mobile applications in spite of the relatively
low weight. Planned future applications include adding force
and torque sensors to enable teleoperated force control.
The arm proposed and specified in the earlier sections was
constructed and mounted on a sturdy industrial work table
(see Figure 1). The lower three actuators have a maximum
output of almost 1.5 kWeach, harmonic drive gearboxes, and
incorporated brakes to lessen motor strain when not moving.
The fourth actuator is similar, but considerably smaller, as it
carries a lighter inertial load. The maximum output is
0.36 kW. The last two joints are contained in a combined pan/
tilt unit. This is less powerful, but has lower weight per joint
than other solutions.
In this article, we have presented the requirement for a highly
dynamic robotic system to be used in studies for ball catching.
From these requirements and a number of secondary goals, a
system has been designed using off-the-shelf actuation modules.
Associated software for real-time control has been designed and
implemented on a commercially available computer platform.
The system operates at 600 Hz and satisfies all the requirements
specified for the design. Results fromearly experiments demonstrate
that the system fulfills the static and dynamic requirements
to allow ball catching.