What Is an Electric Gripper?
A gripper is a mechanism for grasping and holding an object. Among these, an electric gripper is a device that is driven electrically and grips an object.
The shape of the gripper varies depending on the shape and surface properties of the object to be gripped. The most commonly used gripper is the two-finger parallel gripper, in which two parallel members move in a linear motion to clamp and release the object. They are used as devices (end-effectors) that function at the end of robot arms and linear motion mechanisms.
Compared to pneumatic grippers, electric grippers offer more precise control and are used when the size of the object varies or when the gripping force needs to be varied as necessary.
Uses of Electric Grippers
As mentioned above, there are various types of grippers, but here we will discuss the most common type, the two-finger parallel electric grippers.
Since electric grippers can grasp and transport objects, they are used in equipment that lifts and transports objects by combining them with linear motion mechanisms such as cylinders and linear guides. Moreover, by attaching an electric gripper to the end of a robot arm, it is possible to move an object freely in three dimensions, just like a person holding an object.
Principle of Electric Grippers
Electric grippers mainly consist of a finger (sometimes called a claw) for gripping an object, a linear motion mechanism such as a feed screw for moving the finger, and a motor for operating this mechanism. A sensor such as a load cell may be separately incorporated to control the gripping force.
The opening and closing motion can be controlled by controlling the direction and speed of rotation of the motor, and the width of opening and closing can be fed back by reading the number of rotations from the rotary encoder built into the motor. By constructing process control or PID control according to this information, precise control can be achieved, such as slowing down the gripping speed at the moment of contact with the object or setting the distance between the fingers when gripping according to the size of the object.
In the robotics field, however, grippers with three or more fingers are often used to grasp more complex shapes or to learn human motions. Because grippers with three or more fingers require precise control, such as mimicking human motion, most grippers are electric grippers.