Robot coordinate types: joint coordinates and world coordinates
Industrial robots are complex automation devices.
From the aspects of robot installation, teaching, programming, execution, etc., in order to fully unleash the potential of robots, knowledge from multiple aspects is required. Some people feel dizzy when they see that they need to apply this knowledge after buying a robot.
Take the coordinate system of robots as an example, there are the Cartesian coordinate system, the tool coordinate system, the workpiece coordinate system, the flange coordinate system, the base coordinate system... It sounds like they want to retreat.
Don't worry, understand some concepts. Robots, like mobile phones, have a development potential that depends on the user. Therefore, our goal is to know the most important functions of mobile phones, and robots are no exception. Just master the commonly used functions. Our goal is to replace manual labor and automate operations.
Like our Braun robots, we only use two coordinate systems the most, one is world coordinates, One is joint coordinates.
The evidence is that these two most commonly used coordinates were placed on the teaching pendant with separate toggle buttons.
world coordinates
By default, the world coordinate system coincides with the base coordinate system. It is a Cartesian coordinate system used to describe the motion of the robot body. The world coordinate system is a fixed reference frame, usually based on the robot's workspace or factory floor. However, when the robot flips, moves, or has an external axis, the two may not be consistent. The XYZ data of the world coordinate system is the sum of the linkage parameters of each axis, used to represent which point in space the robot is located at.
The use of this coordinate system is particularly simple in teaching devices.
Firstly, you need to learn to look at the XYZ axis,
The X-axis represents the robot moving forward or backward.
The Y-axis represents the entire robot to the left or right.
The Z-axis represents the robot moving up or down.
When we want to control the movement of a robot, we only need to set the starting point of the robot in the world coordinate mode of the teaching pendant, and then control the teaching pendant to move forward, backward, left, right, up, and down, setting the point positions one by one, and the robot can automatically move between points.
In addition, in the world coordinate system, operations can also be performed by setting the Euler angle UVW.
Euler's angle is a method of describing the direction of a rigid body in three-dimensional space through three fundamental rotations, typically represented by three angles (such as Rx, Ry, Rz) around the X, Y, and Z axes.
This way, the robot can confirm its arrival at any position in space at any time.
joint coordinates
The joint coordinate system takes each joint axis as an independent motion unit, and can adjust the angle or position of a joint separately. The rotation or linear motion of each joint forms an independent coordinate axis.
This is a coordinate system set at each joint of the robot, with its origin located at the joint center point, used to describe the relative position and motion of each joint of the robot. Its coordinate system will change with the movement of the joints.
The origin of the joint coordinate system is directly related to the numerical values of the motor encoder. The system records the encoder values in a specific state as the origin, and at this time, the joint coordinate values are all 0. The absolute value encoder used by the robot is powered by the battery in the power-off state. After being powered on again, the system will read and restore the encoder values in memory to ensure that the origin is not lost.
It is worth mentioning that the different structures of industrial robots can lead to different types of joints.
Industrial robots include SCARA robots with horizontal and serial structures, Delta robots with parallel structures, and multi-axis robots with multi-joint vertical serial structures.
Like world coordinates, the robot can also be operated through a teaching pendant. By switching the (J) button in the W/J, the robot can switch joint coordinate motion modes. J1-J6 on the right side of the teaching pendant can control the independent motion of each joint.
The degree of freedom of each joint of a robot is different, and different robots also have different degrees of joint freedom, which depends on the product details.
In the joint coordinate system operation mode, the operation of the robot is also very simple. If you want to move the end of the robot along the desired path, you can control the motion of each axis.
For example, if you want to make one axis of the robot move, you can use j1+to move the robot's one axis to the desired position, then insert it into the endpoint, and finally, in automatic operation mode, the robot can move along the desired path.
The above is the explanation of robot joint coordinates and world coordinates.
By mastering these two, your robot can basically move along the path it wants, without being so complicated.
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