If we want to determine the position of a point in space, we need three parameters:X, Y, and Z, but rigid bodies all have sizes and shapes, not only position, but also attitude. The attitude of the rigid body is described by the angles formed around the X axis, Y axis, and Z axis, and is represented by α, β, and γ respectively. Therefore, six parameters are needed to describe the position and attitude of a rigid body in three-dimensional space. The degrees of freedom of an unconstrained rigid body in three-dimensional space are 6. If the end of an industrial robot wants to achieve unconstrained motion in three-dimensional space, 6 degrees of freedom are needed.
The terminal coordinates of a six-joint industrial robot are expressed in the form of six parameters (X,Y,Z,A,B,C). The six degrees of freedom are translation in three directions and rotation around three axes. Then the six-joint robot can achieve the position and attitude within its range of motion. In fact, not all industrial robots have six degrees of freedom. For example, Scara and Delta robots have only four degrees of freedom. Most right-angle robots also only have 3-4 degrees of freedom. Generally, a simple and crude way to judge how many degrees of freedom a robot has is to count how many motors it has.