Ch7 - Robotic Arm
Manipulators are clever devices designed to do jobs that are too dangerous for humans, or require extreme precision that is unachievable with human hands.
Broadly speaking, robotic manipulators are independent robots, or elements of bigger machines, designed to do the work that was previously done by human hands. This means they have to be highly functional – they have to be able to move in different directions and on different levels.
Argonne National Laboratory, the first science and engineering research national laboratory in the United States, was also the first to build a remote controlled manipulator.
The MSM-8, built in 1945, worked with dangerous, highly radioactive materials, which increased safety of people employed in the facility.
Nowadays, remote-controlled manipulators are used in many different types of work. One of them is space exploration.
NASA space ships also used a remote-controlled manipulator called CANADARM. This robotic arm was 15 metres long and had six joints, so that it could move similarly to a human arm.
CANADARM weighed 410 kilos and had a maximum load of 293 tonnes. It was used to carry satellites or space station modules to the orbit.
Canadarm had an interesting grip. It used three steel ropes tightening into a shape of a triangle.
Candarm was also equipped with many devices that, for example, enabled it to check the state of the heat shields of the spaceship during flight.
The Curiosity rover sent to Mars also uses manipulators.
Curiosity manipulator uses several separate devices to better explore conditions on Mars.
One of these devices is a hammer drill. If a drill breakes, the machine can exchange it for one of the spare drills stored in a special drill compartment. The hammer drill collects powdered rock samples for laboratory research.
Curiosity manipulator also has a device for dusting rocks, a small video camera, and a spectrophotometer – a device for analysing chemical composition of dirt on Mars. Additionally, Curiosity is equipped with a multifunctional device that possesses a scoop for collecting dirt samples, and mechanisms for sieving and portioning rock, dust and dirt samples to prepare them for analysis.
Robots with manipulators are invaluable when it comes to exploring unreachable places on our own planet. One of such places are deep ocean plains.
Underwater vehicles have manipulators that can be equipped with grippers, scissors, video cameras or different kinds of sensors and lights. Data acquired with such devices is used by the military, producers and scientists.
Manipulators used in medicine are also extremely interesting.
A surgeon robot can have arms with attached scalpels, video cameras, or other specialist devices. They are more precise than human hands and allow the surgeon to operate with minimal cutting. A video camera installed on the manipulator arm streams a three dimensional picture to the surgeons, while they perform surgical procedures.
Surgeries performed with such machines are much safer and less demanding for patients.
Build
To build this construction, you will need LEGO Education WeDo
Explore
This is how the complete robotic arm model looks like.
The robot presents how a manipulator operates. It consists of an arm, a gripper and a handle to rotate the construction.
The model has two electronic elements.
1. When connected to the the computer, the hub powers the model and allows you to program it.
2. The motor propels the transmission that grasps and lifts objects.
1. The robotic arm handles various objects with precision. It lifts, moves and lowers them.
You can create your own cargo by using the leftover elements in the set.
1. This is the base of the robot. If you want to incease stability of the robot, connect it to the entire Technic plate.
2. Gray tiles facilitate moving the handle, which rotates the robot.
1. This element turns the robotic arm.
2. By moving the handle, you move the gear rack that turns the cogwheel connected to the construction.
1. This is how the construction turns: the gear rack moves the black cogwheel.
2. The black cogwheel is connected to the arm, which is why when it turns, the entire arm turns as well.
1. Here you can see the range of the robotic arm. It allows you to grasp objects in different places.
1. The gripper can hold objects created with LEGO bricks.
Opening and closing the gripper is possible thanks to the gear train.
1. The first transmission relays the drive from the motor via the small black gear connected to the tan bevel gear onto the axle.
2. The next transmission relays the drive from the axle via two meshed gears onto the small grey gear.
Smaller gears intertwine and transfer the drive to the gripper. When the motor detects resistance, the gripper is lifted.
When activated in the opposite direction, the motor will lower the arm and open the gripper.
Program
Program for the robotic arm will allow you to control the robot by using keyboard. When you press the w key, the arm will lift up. When you press the s key, the arm will go down.
