Robot structure

TECHNOLOGY

By MICHAEL JOHN UGLO
WELCOME to our second lecture on the structure of robots.
Robots are jokingly called liars. A truth is seen to be displayed by something that is artificially programmed by computer algorithms. It is purposely made to help humans to fulfill their needs and aspirations and egos beyond bounds and limits. For instance, robots have been sent to the outer planetary bodies by Nasa to relay information back to the earth.
In order for robots to work there has to be a supply of energy to power up the robot. It is learnt in physics that for work to be done, it has to use energy. Robots can do useful work for humans and therefore these robots need energy to do that work.

Energy as well as work are measured in joules and therefore, they are the same quantity. The work (energy) is as measured in joules is the result of the force (measured in newtons) applied on where ever the environment is multiplied by the distance traveled which is measured in meters.
The source of energy is supplied by a battery as a flow of electrons. The batteries supply direct current. Energy can also be supplied by alternating currents from the mains supply. Whether from batteries or the mains supply or a generator, these can also be converted internally depending on the needs into either ac or dc currents using capacitors and inductors.
Batteries can be obtained from lead-acid for heavier and long life compared to silver-cadmium which is very expensive and smaller in volume. Power can also be obtained from generators that is a form of an internal combustion engine that burns fuel and synchronized to a power line from the conversion of the mechanical energy from the turning coil to flowing electrons as alternating current at certain frequencies measured in Hertz.
The other sources of power can be harnessed for robots from compressed gasses called the pneumatic power, nuclear power, solar power, as well as power from aerobic digestion (from organic garbage) or power from liquids known as hydraulics and also power from flywheel energy storage.
The robots need a form of a muscle to move its parts. These movement of muscles is called activation and it is done from the activators. The activators are motors that are run by the energy supplied from electricity. The electrical energy allows the activators to rotate to produce the required movement circularly like a wheel or a gear. These motions seen in the robots are lighter work and do not involve heavy duty work.

Another type of an actuator is called the linear actuator whereby the activity carried out can be of very heavy duties. These are industrial jobs related and movements are seen to be bidirectional and it is moving in and out. The industrial robots in these jobs are powered by pneumatic actuators or compressed air as well as hydraulic actuators whose principal component is the oil. Industrial robots can also be powered by electricity as well.
The majority of robots are powered by electric motors which are DC motors. These motors are either brushed or brushless. Being portable, these robots can do jobs that are lighter. Robots can also be powered by AC motors such as some industrial robots and their motions are predominantly rotational and involve lighter loads.
A particular structure built to the actuators are in the series elastic actuators. In this structure, there is an intentional elasticity created or introduced between the motor actuator and the load to control the magnitude of the force serially. The resultant force is a of a lower inertia and it protects the robot from abrupt contacts and collisions that could result in wear. It cushions the robot from any adverse encounters with the environment and provides a certain degree of freedom for safeguarding in those instances.
There are further particular structures and those are called the air muscles seen in the robots. These are called the pneumatic artificial muscles. In these structures, air is pumped into the specially made tubes that inflate to about less than half its volume to about 42 per cent. It also deflates according to the pneumatic pressure required to accomplish the particular task desired. Hence, the control can be passed back and forth depending on the requirement.
There are also other structures called the wire muscles. These wires which are alloys are known as the Nitinol or the Flexinol wires. In minor applications, this specific group of wires also known as shape memory alloys can contract to about a magnitude of 5 per cent upon receiving an electric current. This is a special character that are made use of in building robots.
Further structures are made use of in a particular property of the plastics called the EAP and EPAM on the reception of electricity. These are a special plastic that are categorized as the electroactive polymers. These plastics can contract down to about less than three (3) and a four fifth (4/5) times its size or at approximately about 380 per cent contraction. This property of the plastic is used specifically in the facial expressions that provides the flexibility therein. Thus, the computer control can be passed back and forth from memory to provide the degree of freedom for this particular series of desired actions.
There is the group of motors found in the robots called the piezo motors. These motors are made available through technology. These are a replacement for the common DC motors used in the robots.
The motors are called the piezo motors and also known as the ultrasonic motors that operate from a nano amplifying effect from its collective vibrations. These vibrations come from its tiny piezoceramic elements that resonate many thousand times a second and these can be condition to cause the rotational motions steps as well as the steps in the linear motions as desired.

The operating principle in this motor is different and is in nanometer scale. The many nanoscale vibrations can be tapped to make a nut to vibrate or either to drive a screw. The control in this application is the harvest of the nanoscale resolution of speed and force for their size and many robots are constructed from it and are commercially available.
The promising muscle structure for the robots currently at a nanoscale is the carbon nanotube’s elastic nanotube. It is defect-free and just a portion of about a magnitude of 8mm diameter of this wire can replace the human biceps. This is a real compact muscle and can outrun and out jump humans at this same magnitude.
The sensing part of a robot is the particular area of utmost interest because it is through this special attribute that a robot is seen to be called what it is to do as its job. The sensing involves detecting the condition of the environment and this job is performed by the sensors. The sensors are powered by a mini-battery or a photovoltaic cell for two to sense the variations in the stimulus. This is the form of signals it receives from the environment. That particular change is communicated to the control hub of the robot that activates a manipulator to perform those actions through its effectors.
The touches of the human hand on objects are mimicked to that of the robot’s hands and particularly the finger tips. There is touch tactile for information reception developed on a prosthetic hand in the latest development by scientists from several European countries and Israel. A conductive fluid is placed around the skin with a hand and an electrode is placed at the center of the conducting fluid and is connected to an impedance measuring device.
When in contact with the environment, the fluid is displaced proportional to the magnitude of the applied force or impedance. Hence, the robot is programmed to act or respond according to the impact is mapped proportional to the impedance. In effect the prosthetic hand can play piano, can write and can also type on a keyboard and is of particular use to patients.
The images revealed by a robot as its vision is a common place in science and technology. Light is detected from the environment through a visible light ray or even heat in the form of infra-radiation. It is incident to a transistor to magnify its amplitude for processing in a solid-state semiconductor device to iteratively differentiate the obscured areas like differences in the shades. In so doing a photographic image is produced.
Robots can be equipped with such equipment and a software programme to process the image or take pictures as briefly outlined above. Formations of pictures whether it is generated through the pixels in the computing using solid state physics there is also quantum mechanics methodology for image processing technology using the vision as studied from the biological systems is a huge area in vision in the robots.
My Prayer for PNG today is: “When we all, get to Heaven, what a day of rejoicing that will be. When we all see Jesus. We’ll sing and shout the victory”
Next week: Works and traversals of robots

• Michael Uglo is a science textbook author and a lecturer in avionics, auto- piloting and aircraft engineering. Please email any comments to: [email protected]