The history of robots is not long; it truly began in 1959 when Engelberger and Devol created the world’s first industrial robot. Engelberger studied servo theory in college, which is a theory that studies how motion mechanisms can better track control signals. Devol invented a system in 1946 that could “replay” the recorded movements of machines. In 1954, Devol obtained a patent for a programmable mechanical hand, which could work according to a program and could be programmed differently based on various work needs, thus possessing versatility and flexibility. Engelberger and Devol both researched robots and believed that the automotive industry was most suitable for robots because it involved heavy machinery and a relatively fixed production process. In 1959, Engelberger and Devol collaborated to manufacture the first industrial robot.
Classification of Robots
Regarding how robots are classified, there is no unified standard internationally. Some classify them by load weight, some by control method, some by degrees of freedom, some by structure, and some by application field. The general classification methods are:
Teaching Reproduction Robots: These robots learn actions through guidance or other means, input work programs, and then automatically repeat the tasks.
CNC Robots: These robots do not require physical movement; they are taught through numerical values, language, etc., and perform tasks based on the taught information.
Sensor-Controlled Robots: These robots use information obtained from sensors to control their movements.
Adaptive Control Robots: These robots can adapt to changes in the environment and control their own actions.
Learning Control Robots: These robots can “experience” work and possess a certain learning function, applying the “learned” experiences to their tasks.
Intelligent Robots: These robots determine their actions based on artificial intelligence.
In China, robot experts classify robots into two main categories based on their application environment: industrial robots and special robots. Industrial robots refer to multi-joint mechanical arms or multi-degree-of-freedom robots aimed at the industrial field. Special robots are advanced robots used in non-manufacturing sectors to serve humans, including service robots, underwater robots, entertainment robots, military robots, agricultural robots, and robotic machines. Among special robots, some branches are developing rapidly and tend to form independent systems, such as service robots, underwater robots, military robots, and micro-operation robots. Currently, international robotics scholars also classify robots into two categories based on application environments: industrial robots in manufacturing environments and service and humanoid robots in non-manufacturing environments, which aligns with China’s classification.
Advantages and Disadvantages of Robots
Advantages of Using Robots:
Robots and automation technology can generally improve productivity, safety, efficiency, product quality, and uniformity;
Robots can work in hazardous environments without considering life support or safety needs;
Robots do not require comfortable environments, such as considerations for lighting, air conditioning, ventilation, and noise isolation;
Robots can work tirelessly and without boredom; they do not have psychological issues, do not procrastinate, and do not require medical insurance or vacations;
Robots will maintain precision consistently, except for failures or wear;
Robots have much higher precision than humans. Linear displacement precision can reach thousandths of an inch (1 inch = 2.54 cm), and new semiconductor chip processing robots have micro-inch level precision;
Robots and their associated devices and sensors possess certain capabilities that humans do not have;
Robots can respond to multiple stimuli or handle multiple tasks simultaneously, while humans can only respond to one current stimulus.
Negative Aspects of Using Robots:
Robots replace workers, leading to economic and social issues;
Robots lack emergency capabilities; unless the emergency situation can be anticipated and a response plan has been set in the system, they cannot handle emergencies well. Additionally, safety measures are needed to ensure that robots do not harm operators or the machines (equipment) they work with. These situations include: inappropriate or incorrect responses, lack of decision-making ability, power outages, damage to robots or other equipment, personal injury;
Although robots excel in certain situations, their capabilities still have limitations compared to humans, manifested in: degrees of freedom, dexterity, sensor capabilities visual systems, real-time response.
Components of Robots
As a system, a robot consists of the following components:
Mechanical Arm or Mobile Vehicle: This is the main part of the robot, composed of links, movable joints, and other structural components, allowing the robot to reach a specific position in space. Without other components, the mechanical arm alone is not a robot (equivalent to a human body or arm);
End Effector: This is the component connected to the last joint of the mechanical arm, generally used to grasp objects, connect with other mechanisms, and perform required tasks. In robot manufacturing, end effectors are generally not designed or sold; most of the time, they only provide a simple gripper (equivalent to a human hand).
The end effector is installed on the robot to complete tasks in a given environment, such as welding, painting, gluing, and loading/unloading parts, which are just a few tasks that may require robots. Typically, the actions of the end effector are directly controlled by the robot controller or the signals from the robot controller are sent to the end effector’s own control device (such as PLC);
Actuator: The actuator is the “muscle” of the mechanical arm. Common actuators include servo motors, stepper motors, cylinders, and hydraulic cylinders, as well as some new types of actuators used in specific situations, which will be discussed in Chapter 6. The actuator is controlled by the controller.
Sensors: Sensors are used to collect information about the internal state of the robot or to communicate with the external environment. The robot controller needs to know the position of each link to understand the overall configuration of the robot. Even in complete darkness, humans can know where their arms and legs are because the sensory neurons in the central nervous system feedback information to the brain. The brain uses this information to determine the degree of muscle extension and thus ascertain the state of the arms and legs. For robots, integrated sensors within the robot send information about each joint and link to the controller, allowing the controller to determine the robot’s configuration. Robots are often equipped with many external sensors, such as vision systems, tactile sensors, and speech synthesizers, to enable communication with the outside world.
Controller: The robot controller obtains data from the computer, controls the actions of the actuators, and coordinates the robot’s movements with feedback information from the sensors. For example, if a robot needs to take a part from a cabinet, its first joint angle must be 35°. If the first joint has not yet reached this angle, the controller will send a signal to the actuator (delivering current to the motor) to make the actuator move, and then measure the change in joint angle through feedback sensors (such as potentiometers or encoders). When the joint reaches the predetermined angle, the controller stops sending control signals. For more complex robots, the robot’s speed and force are also controlled by the controller. The robot controller is very similar to the human cerebellum; although the cerebellum’s functions are not as powerful as those of the human brain, it controls human movements.
Processor: The processor is the brain of the robot, used to calculate the movements of the robot’s joints, determine how much and how far each joint should move to reach the desired speed and position, and supervise the coordination of actions between the controller and sensors. The processor is usually a dedicated computer. It also needs to have an operating system, programs, and external devices like monitors.
Software: The software used for robots generally consists of three parts. The first part is the operating system, used to operate the computer. The second part is the robot software, which calculates the actions of each joint based on the robot’s motion equations and then transmits this information to the controller. This software varies in levels, from machine language to high-level languages used in modern robotics. The third part consists of routine program collections and applications developed for using external devices of the robot (such as vision general programs) or for performing specific tasks.
In many systems, the controller and processor are placed in the same unit. Although these two parts are housed in the same device box or even integrated into the same circuit, they have their own functions.
Performance Indicators of Robots
The following items are used to define the performance indicators of robots:
Load Capacity: Load capacity is the weight that a robot can bear while meeting other performance requirements. For example, a robot’s maximum load capacity may be much greater than its rated load capacity, but when reaching the maximum load, the robot’s working precision may decrease, and it may not be able to move accurately along the predetermined trajectory or produce additional deviations. The load capacity of robots is often very small compared to their own weight. For example, the Fanuc Robotics LR Mate robot weighs 86 pounds, while its load capacity is only 6.6 pounds; the M16 robot weighs 594 pounds, while its load capacity is only 35 pounds.
Range of Motion: The range of motion is the maximum distance a robot can reach within its working area. Robots can reach many points in their working area in any posture (these points are called dexterous points). However, for some points close to the limits of the robot’s range of motion, their posture cannot be arbitrarily specified (these points are called non-dexterous points). Note: The range of motion is a function of the lengths of the robot’s joints and its configuration.
Precision: Definition: Precision refers to the degree of accuracy with which a robot reaches a specified point. Note: It is related to the resolution of the actuators and the feedback devices. Most industrial robots have a precision of 0.001 inches or higher.
Repeatability: (Variability) Definition: Repeatability refers to the degree of accuracy with which a robot reaches the same position if the action is repeated multiple times. For example, if a robot is driven to the same point 100 times, due to many factors affecting the robot’s positional accuracy, it cannot reach the exact same point every time, but should be within a circular area centered on that point. The radius of this circle is formed by a series of repeated actions, and this radius is the repeatability. Note: Repeatability is more important than precision; if a robot’s positioning is not accurate enough, it usually shows a fixed error that can be predicted and thus corrected through programming. For example, if a robot always deviates 0.01mm to the right, all position points can be specified to shift 0.01mm to the left, thus eliminating the deviation. Note: If the error is random, it cannot be predicted and therefore cannot be eliminated. The repeatability limits the range of such random errors, usually determined by running the robot a certain number of times.
The editorRobotics is an interdisciplinary field with a very broad range of knowledge. If you want to understand more detailed knowledge about robots, you need to read more related books. Here, I recommend two books published by the Machinery Industry Press on the basics of robotics, hoping to help everyone understand the robot industry!
For more professional books on robotics, you can click the “Learn More” button below to enter the Jinfen Mall’s robotics book section!
Purchase
Learn More
Click the QR code below to directly enter the “Jinfen Mall” to purchase other books from the Machinery Industry Press!
