Factors affecting the positioning accuracy of cartesian robot

With the rapid development of industrial automation, the application of Cartesian coordinate robots is more and more widely used, but the accuracy needs to be higher in specific applications.The rectangular coordinate manipulator is composed of multi-axis XYZ linear modules. When the structural rigidity and contact stiffness of the three-axis manipulator itself are low, the vibration is easily generated and the positioning accuracy is generally low.
Then how to operate to ensure its stability and accuracy?

1. First of all look at the accuracy of the uniaxial linear module, its stability and accuracy are maintained by:
a. Accuracy grades of screw, guide rail, supporting seat and bearing of the main parts of the product;

b. The degree of parallelism between the screw rod and the guide rail when assembling, and the guarantee of the concentricity between the screw rod and the bearing;

2. The accuracy of multi-axis combination depends on:
a. Multi-axis robot mounting platform rigidity and flatness;
b. Assembled precision assurance equipment and professional technical requirements and process requirements;
c. Positioning speed: The positioning speed has a great influence on the positioning accuracy.
This is because when the positioning speed is different, the energy of the moving parts that must be dissipated is different.
Generally, in order to reduce the positioning error, the positioning speed should be reasonably controlled, such as increasing the buffering performance and buffering efficiency of the buffer device, and controlling the drive system to decelerate the moving parts in a timely manner.
d. Weight of the endless workpiece: When the weight of the moving part increases, the positioning accuracy decreases. Therefore, the design must not only reduce the weight of the moving parts themselves, but also take into account the impact of changing the weight of the work.
e. Drive source: The pressure fluctuation of hydraulic pressure and air pressure, and the fluctuation of voltage, oil temperature and air temperature all affect the repeatability of the manipulator. Therefore, the necessary regulation and adjustment of the oil temperature are adopted.
If the accumulator is used to stabilize the oil pressure, the heater or cooler is used to control the oil temperature. When the speed is low, the temperature and pressure compensation flow control valve is used for control.
f. Control system: The position control accuracy of switch control, electro-hydraulic proportional control and servo control is different. This is not only because the accuracy and sensitivity of various control elements are different, but also related to the presence or absence of position feedback devices.