Robot Actuator : Types, Design, Working & Its Applications - ElProCus

We know that robots are advanced and highly intelligent electromechanical devices that can perform a number of daily tasks. This device is capable of responding to its surroundings & making actions to attain a specific task. Robots are made with different components but one of the significant components is the actuator. Generally, actuators are used in almost every machine around us like electronic access control systems, mobile vibrators, household appliances, vehicles, robots & industrial devices. The general actuator examples are; electric motors, jackscrews, stepper motors, muscular stimulators within robots, and many more. This article gives brief information on a robot actuator – working with applications.

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What is a Robot Actuator?

An actuator that is used in robots to make the wheels of the robot turn or robot arm joints turn or to open/close the gripper of the robot is known as a robot actuator. There are different types of robotic actuators are available based on the load involved. Generally, the load is associated with different factors like torque, force, accuracy, speed of operation, power consumption & precision. The working principle of a robot actuator is to change the energy into physical motion and most actuators generate linear or rotary motion.

Types of Robotic Actuators

Robotic actuators are classified into two types according to the requirements of motion like linear motion & rotational motion.

For Linear Motion:

There are two types of actuators used in robots for linear motion activity they are; linear actuators and solenoid actuators.

Linear Actuators

Linear actuators in robotics are used to push or pull the robot like move forward or backward & arm extension. This actuator’s active end is simply connected to the robot’s lever arm to activate the such motion. These actuators are used in a number of applications in the robotics industry.

Solenoid Actuators

Solenoid actuators are special-purpose linear actuators that include a solenoid latch that works on electromagnetic activity. These actuators are mainly used for controlling the motion of the robot and also perform different activities such as a start & reverse, latch, push button, etc. Solenoids are normally used in the applications of latches, valves, locks, and pushing buttons which are controlled normally by an external microcontroller.

For Rotational Motion:

There are three types of actuators used in robots for rotational motion activity they are; DC motor, servo motor, and stepper motor.

DC Motor Actuators

DC motor actuators are generally used for turning robotic motion. These actuators are available in different sizes with torque generation capability. Thus, it can be utilized for changing speed throughout rotating motions. By using these actuators, different activities like robotic drilling & robotic drive train motion are performed.

Servo Actuators

Servo motor actuators in robotics are mainly used to control & monitor rotating motion. These are very superior DC motors that allow 360 degrees of rotation, but, continuous revolution is not compulsory. This actuator simply allows halts throughout a rotating motion. By using this actuator, the activity like pick and place is performed. To know how a Pick N Place robot works click on the link.

Stepper Motor Actuators

Stepper motor actuators are helpful in contributing to repetitive rotating activities within robots. So these types of actuators are a combination of both DC & servo motor actuators. These stepper motor actuators are utilized in automation robots where repeatability of activity is necessary.

Robot Actuator Design

We know that there are different types of actuators used in robots. Here we are going to discuss how to design a linear actuator that is used in robotics for changing rotating motion into a pull/push linear motion. So this motion can be used to slide, drop, tilt or lift materials or machines. These actuators provide clean & safe motion control that is very efficient & maintained free.

Power

The first consideration while designing a robot actuator is Power. To obtain mechanical power out, it is essential to have power in. So, the amount of mechanical power out can be defined by the load or force to be moved.

Duty Cycle

The duty cycle can be defined as how frequently the actuator will work & the amount of time it will use. The duty cycle is determined by the actuator’s temperature when it is in motion since power is lost throughout the heat.

When all the actuators are not the same, then there is a difference within their duty cycles. One more factor is the load, which is particularly true of DC motors whereas other factors that can determine the duty cycle are loading characteristics, age & ambient temperature.

Efficiency

The actuator efficiency simply helps in understanding how it will work while in operation. So, the actuator’s efficiency is found by separating mechanical power generated by electrical power.

Actuator Life

There are many factors that will extend the actuator’s life are; staying in the rated duty cycle, reducing side load, and staying in the recommended voltage, force, and extreme environments.

Working

Robot actuators are mainly designed for ease of use & efficiency. The design of a linear robot actuator is the inclined plane that starts with a threaded lead screw. This screw provides a ramp to generate force that works along with a larger distance to move any load. The main purpose of robot actuator design is to provide pull/push motion. So, the required energy to provide the motion is manual or any energy source like electricity, fluid, or air. These actuators generally move car seats forwards & backward, open automatic doors, computer disk drives opening and closing.

Robot Actuator Failure

The robot actuator failure mainly occurs due to many reasons. So these actuators can experience different failures like stuck joints or locked, free-swinging joints & total or partial loss of actuation efficiency. So, these failures will affect robot behavior if the controller of the robot has not been designed with sufficient fault tolerance.

How to Choose an Actuator for your Robot?

Robot actuators are used for different purposes, so there are many aspects to consider while selecting actuators like

Purpose & Intended Functionality

The necessary actuator type for a specified application mainly depends on the purpose of a robot as well as the intended functionality.

Physical Requirements & Constraints

Whenever the type of actuator is decided to use, then developers must look at the physical requirements & constraints. Because the weight & physical size of the actuator plays a key role while arranging the actuator in the robot otherwise a heavy actuator on a tiny robotic arm may cause to fail the arm in its own weight.

Strength & Power

Based on their particular usage, developers must ensure the strength and power of a specified actuator to perform the task.

Communication Protocol

The communication protocol should also be considered while selecting an actuator for the robot. Many actuators simply support communications with PWM (pulse width modulation) whereas some actuators support serial communications.

Mounting Space & Options

Developers should verify the mounting space obtainable in or on the robot & the mounting options given by the actuator itself. Because some types of actuators are available with separate mounting hardware that allows you to mount the unit within different orientations whereas others are available with integrated mounting points, which are installed into a particular position & orientation.

Advantages

Robot actuator advantages include the following.

• Less cost
• Its maintenance is easy.
• These are accurate.
• Easy to control.
• Power conversion efficiency is high.
• Safe & simple to operate
• Less noise.
• These are very clean & less pollution to the atmosphere.
• These are very easy to maintain.

Robot actuator disadvantages include the following.

• Overheating within fixed conditions.
• Need special safety within flammable environments.
• Need good maintenance.
• Fluid leakage will create ecological problems.
• Loud & noisy.
• Lack of accuracy controls.
• These are very sensitive to vibrations.

Robot Actuator Applications

The applications of robot actuators include the following.

• The actuator is a very significant component in robotics which changes the external energy into physical motion depending on the control signals.
• The electrical actuators in robotics are used to change the electrical energy into rotary or linear motion
• Actuators generate forces that robots use this force to move themselves & other objects.
• Actuators are associated with robotics, devices, or prosthetic arms which need to move & bend.
• The linear actuators within robotics change electric energy into linear motion.
• An actuator is responsible for controlling & moving a system or mechanism.

There are various types of robot joints. It’s helpful to learn about these different joints so you can better understand the workings of the robots you are using.

Each joint type will affect the range of motion and capabilities of your robot.

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The challenge for newer robot users is that there are different ways to categorize robot joints. This can make them confusing.

A basic understanding of the types of joints can really help you get the most from your robots. In this article, we explore the various ways you can look at robot joint types.

How Do You Determine Different Robot Joint Types?

Like many people, you might just look at a robot and see it as a single machine. The robot operates as a single unit. However, you can also “zoom in” on the robot and look at its component parts.

All industrial robots are basically just a chain or collections of “joints.” Robot joints are mechanisms that create motion in one or more of the robot’s axes. Together, the robot’s joints create the desired motions of a robot’s limbs.

It’s helpful to know about robot joint types so you can understand which robots will be most suitable for your needs.

There are 3 basic ways you can categorize robot joints:

1. By actuation type
2. By kinematic design
3. By joint function

Each of these offers a useful perspective as to what makes a particular robot joint work. We’ll look at each of them in turn below.

3 Types of Robot Joint by Actuation Type

The first way to categorize robot joints is by their actuation type. An actuator refers to any mechanical or electromechanical device that creates motion. The actuator generates a force using a particular type of energy.

Here are the 3 basic types of robot actuators:

1. Electric

An electric actuator converts electrical energy into motion with an electric motor. This creates a torque that moves the robot joint.

Electric actuators are probably the most common actuator type in robotics. They are fast, precise, and very portable. Although they are not as powerful as the other 2 types of actuator, they offer a good cost-to-strength ratio.

2. Pneumatic

A pneumatic actuator creates force through the application of compressed air. As many manufacturing facilities already have pneumatic lines installed, this can be a handy option and is often used for robot tools.

Benefits of pneumatics include its fast speed and simplicity. However, it offers limited power compared to hydraulics and requires a lot more extra hardware (pumps and pipes) compared to electric systems.

3. Hydraulic

A hydraulic actuator uses pressurized liquid to create motion. They offer more strength than the alternatives, which is why hydraulics are often used for heavy-duty applications.

Hydraulic robots are often the strongest with a high range of mobility. However, they are expensive, require high maintenance, and can be very messy if the liquid leaks.

3 Robot Joint Types by Kinematic Design

Another way to look at robot joints is to classify them by how they move. This is determined by their kinematic design. Each joint will have one or more degrees of freedom which are arranged differently depending on the joint type.

Here are the 3 most common joint types by kinematic design:

1. Linear

A linear or prismatic joint can move in a translational or sliding movement along a single axis.

It is probably the simplest type of joint to imagine and is the easiest to control. Actuating the joint makes it longer or shorter.

2. Revolute

A revolute or rotational joint moves around a point about one degree of freedom. You can think of a revolute joint as being like the elbow joint in your arm — it can bend only in one direction.

Most industrial robots comprise a series of revolute or rotational joints. As a result, there are well-established control strategies for revolute joints.

3. Spherical

A spherical joint can move in multiple degrees of freedom around a single point. You can think of a spherical joint as being like the top shoulder joint of your arm — it can move in multiple directions but around the same point.

Spherical joint control can get quite complex. Sometimes, it’s easier to describe the spherical joint as being 3 revolute joints with an axis that intersects at a common point.

3 Robot Joint Types by Function

The last way to look at robot joints is often the most useful for industrial robotics. Here, we look at the robot joint by its function or role in an industrial manipulator.

The 3 functions of an industrial manipulator joint are:

1. Shoulder Joint

The shoulder joint sits at the base of a robotic manipulator.

It is often the biggest joint and determines how much the robot can turn around. It has the most significant effect on the size of the robot’s workspace.

2. Elbow Joint

The elbow joint sits in the middle of the robotic manipulator.

It has the most impact on the robot’s lifting strength and sets a large proportion of the robot’s range of motion. If the elbow joint is restricted, the robot’s workspace will also be restricted.

3. Wrist Joint

The wrist joint sits at the end of the robotic manipulator.

It has the most effect on the position of the robot’s end effector. Often, wrist joints can spin a full 360 degrees. It is also subjected to more vibrations caused by the environment than other joints.

What Do You Really Need to Know About Robot Arm Joint Design?

Now that you know the basics of robot joints, you can understand a little more about how robots are designed.

However, unless you are building your own robots, you probably don’t need to know much more. It’s most useful when you know the type of robot that you will use and how you can apply them to your particular application.

With the right robot programming tool, the software handles most of the complexity.

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