What Is a Robot Hand?
A robot hand is a component attached to the end of an industrial robot for gripping the object to be conveyed.
Robot hand may be changed according to the shape of the object to be transported and may be replaced depending on the object to be transported. While a robot hand needs to be able to grasp the object to be conveyed, it is also essential for it to be safe.
Since robots move unattended, they generally do not stop even if a person comes in contact with them. If the robot’s hand is sharply shaped, it may injure a person. Therefore, measures such as wrapping the hand with urethane may be necessary.
Applications for Robot Hands
Robot hand is used in a variety of industrial robots, including vertically articulated robots, horizontally articulated robots, Cartesian Coordinate Robots, and parallel link robots. The robot hand has an appropriate shape depending on the object to be conveyed.
When transporting cardboard, for example, a gripping type robot hand with two plate-shaped jaws can be used. In this case, the two jaws clamp the cardboard from both sides and lift it. To prevent the cardboard from falling, measures may be taken to bend the lower side of the jaws inward slightly.
Robot hand of the suction type can be used for transporting objects such as one-liter pails or pails. In this case, a vacuum is applied to the container with the suction pad placed on the top surface of the container. In some cases, an ejector as well as a pump is used to create a vacuum.
Principle of Robot Hands
Robot hands of the gripping type are called Soft Grippers, which can grip fragile (fragile) materials such as food. The hand is made of flexible silicone, so it will not break even if it grips the object to be conveyed.
Suction pads used in suction-type robot hands come in a variety of shapes, including round, flat, bellows, and elliptical bellows. The suction pad has a suction port. Suction is applied through this port to reduce the pressure inside the suction pad.
It is important that the contact surface of the suction pad be in firm contact with the material to be conveyed. Decompression is performed by a vacuum pump or an ejector using compressed air. When a vacuum is created, the contact surface is stuck to the object to be conveyed, thus completing suction, and when the decompression is released, the contact surface can be released from the object.
In addition to gripping, other functions have recently been incorporated into robot hands, including image recognition. By attaching a camera or other image recognition device to the robot hand, it can take pictures of the object from the robot hand and automatically recognize where it is being handled. This function can be applied to a wide range of applications, for example, selectively grabbing randomly placed bolts.
Types of Robot Hands
Robot hands can be broadly classified into two types: gripping type and suction type.
1. Grasping Type
Robot hands with two or three claws are commonly used, but there are also robot hands with five fingers, just like a human hand. They are capable of gripping objects of complex shapes.
2. Suction Type
The suction-type robot hand is equipped with a suction pad and grips the object to be conveyed by vacuum suction. It can grab the object to be conveyed in a short time. Some suction-type robot hands also use magnetic suction to grip the object to be conveyed.
How to Select a Robot Hand
A robot hand that can do everything as dexterously as a human being does not yet exist. Therefore, it is necessary to select an appropriate robot hand for the job you want to accomplish (e.g., picking up an empty can with a robotic arm and placing it at an arbitrary location).
First, it is important to consider “How will the robot grab the object to be transported?” is important to consider. For example, there are several options, such as “whether to grasp and hold the object to be conveyed like a human hand,” “whether to hold the object by vacuum suction,” “whether to hold the object by magnetic suction,” and so on.
The method selected depends on the characteristics of the object to be conveyed. The characteristics of the object to be considered when considering the retention method are as follows
- What is the hardness of the object to be conveyed?
- Is the environment suitable for adsorption or generation of magnetic force?
- What is the speed at which the robot can transport the object?
- What is the shape of the object to be conveyed?
Once the grasping method is determined based on these items, the specific robot hand to be employed is considered according to “size and center of gravity position,” “surface material,” and “holding area.
Other Information on Robot Hands
How to Make Your Own Robot Hands
A simple structured robot hand is relatively easy to make, even for an amateur. For example, consider the case of a hand attached to the arm of a crane game.
The hand is driven by a servo motor and holds the object to be transported between two L-shaped plates.
- Prepare two L-shaped boards or the like.
- Connect a servo motor to one of the boards, so that when the servo motor rotates, the board moves together.
- Connect the two L-shaped boards with hinges.
When two L-shaped plates are joined together with hinges, one of the plates moves closer to the other, thus enabling the grasping of the object to be conveyed. Other types of hands that are made by factory production engineers, for example, employ an air cylinder or NC cylinder as a gripping jaw.