Understanding a robotic arm mechanism

What are the components of a robotic arm mechanism?

• The base allows the arm to stay fixed in one place. It’s attached to a surface like a table, wall, or floor and provides stability for the arm.
• The shoulder joint allows the first arm segment to rotate from side to side. It gives the arm horizontal reach and motion.
• The elbow joint connects the upper and lower arm segments. It bends to give the arm vertical motion and reach. Thanks to the shoulder and elbow joints, robotic arms have a wide range of motion similar to a human arm.
• The wrist joint is at the end of the lower arm segment. It allows the end-effector or "hand" to rotate and bend. The wrist provides dexterity so the end-effector can grab and manipulate objects.
• The end-effector is at the end of the wrist joint; it’s designed to interact with the environment and is often a gripper for grasping objects. The end-effector comes in many types like claws, fingers, and magnetic heads depending on the arm's application.
• Actuators and motors power the joints and end-effector. They provide the force and motion control for each part of the arm. Rotary and linear actuators are commonly used in robotics.

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What are robotic gripper mechanisms?

Robotic gripper mechanisms are the end-effectors on a robotic arm that physically manipulate objects. 

They’re designed to grab, carry, and release materials during automated tasks. 

• Mechanical grippers that use actuators to open and close movable fingers around an object are the most common.
• Vacuum grippers use suction cups to pick up smooth, non-porous objects like glass or polished metal. They create an airtight seal between the gripper and object surface, allowing the gripper to lift and move the item. 
• Magnetic grippers contain electromagnets to handle ferrous metals like steel. When energized, the electromagnets generate a magnetic field that attracts the metal object.
• Some grippers combine multiple grasping methods, such as mechanical fingers with built-in suction cups or electromagnets. Dual gripper designs have a separate gripper for each hand, allowing the robot to grasp and manipulate objects that require two contact points for stability, like ladders or furniture.
• For delicate tasks, soft gripper pads or grippers made of pliable materials are used to avoid damaging the object's surface. Precise, responsive grippers enable robots to perform detailed work or manipulate irregularly-shaped objects. Robotic gripper technology continues advancing to equip robots with human-like dexterity and problem-solving skills.

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What are the joints in a robot arm?

A robotic arm consists of multiple joints that provide movement and flexibility. The joints connect the rigid links of the arm and allow it to bend, rotate and extend to different positions.

The three main types of joints found in a standard robotic arm are:

• Rotational joints, like the shoulder joint, allow the arm to rotate around an axis. They provide rotational movement measured in degrees.
• Flexion joints, such as the elbow, allow the arm to bend inward and outward. They provide flexion and extension movement.
• Extension joints, such as the wrist joint, allow the arm to move up, down, left, and right. They provide lateral movement and extension.

The combination of different joints with various ranges of motion allows the robotic arm to achieve a high degree of dexterity and manipulate objects precisely. Multiple joints working together allow the arm to reach around obstacles and into confined spaces.

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What are the 7 types of robot arms?

Robot arms come in a variety of configurations to suit different needs. 

The 7 most common types are:

• Cartesian coordinate robot – This simple but effective design moves along three linear axes (x, y and z). It's easy to program but limited to straightforward pick-and-place tasks.
• Cylindrical-coordinate robot – With a cylindrical design, this type of arm has two linear axes (z and r) and one rotary axis (θ) for extending, raising, and rotating the end-effector. It offers more flexibility than the cartesian type.
• Polar coordinate robot – Using one linear axis (z) and two rotary axes (θ and φ), the polar arm can achieve an expanded range of motion for more complex assembly or welding operations. Its design takes up minimal space.
• SCARA robot – Selective Compliance Assembly Robot Arm or SCARA robots have two parallel rotary joints that provide left-right movement and up-down motion. They are fast, precise, and ideal for assembly line work like electronics manufacturing.
• Articulated robot – An articulated arm has three or more rotary joints that operate like a human arm. It offers the greatest flexibility and dexterity for handling larger payloads or navigating confined spaces. Programming and controlling articulated robots tend to be quite complex, however.
• Parallel robot – This unique design has two platforms connected by several articulated legs. It allows for high speed, high precision, and high rigidity, suitable for applications like flight simulators or wafer fabrication. But parallel robots also tend to be difficult to program and control.
• Anthropomorphic robot — With a human-like form including an arm, torso, and head, the anthropomorphic robot is highly articulated and mobile. Anthropomorphic designs are still quite limited in capability and mainly used for research purposes to study robot-human interaction.

Find out more in our in-depth article here.

What is a robotic servo motor?

The servo motors in robotic arms are responsible for controlling the angular position of the joints. These motors receive signals from the robot’s control system that determine the position the joint needs to move to. 

Some key features of servo motors in robotics include:

• They have built-in control circuits that allow them to rotate to a specific position and hold that position. This is unlike a standard motor which just spins continuously.
• They typically have a range of motion of 180 degrees or less. Multiple servo motors are linked together in a robot arm to achieve a wide range of motion.
• They’re designed to provide a high torque, or turning force, to lift and move the weight of the robot arm and any objects it may be manipulating.
• They’re very responsive, and capable of quickly changing the position of the joint based on control signals. This allows for smooth, precise movements of the robotic arm.

Read more in our article here.

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What can robotic arms be used for?

Robotic arms have a variety of useful applications across industries. 

Let’s check them out:

Assembly

Robotic arms are commonly used for assembling components or finished products. They can handle small, intricate parts and manipulate them with high accuracy. 

Robotic assembly allows for faster, more consistent production of goods ranging from electronics to vehicles.

Material handling

Robotic arms equipped with grippers or suction cups can grasp and move materials around a factory or warehouse. They’re employed for sorting, palletizing, packaging, and transporting all types of objects. 

Using robotics for material handling reduces physical strain on human workers and minimizes product damage.

Inspection

Some robotic arms have built-in cameras and sensors to detect defects or take measurements. 

They’re useful for quality control applications like surface inspection, dimension verification, and x-ray testing. 

Automated inspection improves accuracy and helps identify imperfections that human inspectors might miss.

Hazardous jobs

Any job that might be dangerous for humans to perform is an ideal application for robotic arms. They can handle toxic chemicals, work in extreme heat or cold, lift heavy payloads, and conduct repetitive tasks without fatigue. 

Robotic arms save lives by taking over dangerous jobs in factories, labs, and other hazardous work environments.

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Summing up

Understanding how robotic arms operate takes some work, but you're now equipped with knowledge about the key components like joints, motors, and grippers that power these state-of-the-art automation tools. 

Whether you're an engineer looking to design a new robot arm or a business owner looking to bring automation to your factory, now you can dive even deeper!

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Next steps 

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• Continual learning and adaptation: RO1 distinguishes itself in automation by learning from real-world interactions, adjusting to new challenges, and autonomously optimizing its functions.

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