I. Introduction

With the improvement of the automation of industrial production lines, Industrial manipulators are frequently used in production processes such as painting, packaging, welding, and assembly to replace manual labor in harsh environments. Here, a six-axis hot-dip galvanizing manipulator is used as an example for description. Mechanically, the six-axis robotic arm is structurally designed with a 6-degree-of-freedom space coordinate system. All of the six axes work with servo motors with reducers, and finish corresponding actions with servo driver controlled by Karnop Robot control system.

2. System Introduction

1. Characteristics of six-axis industrial manipulator:

(1) High speed: Lightweight devices and high-power micro motors are used to increase the speed, thereby shortening the cycle time and improving production efficiency.

(2) High precision: The six-axis industrial manipulator adopts high-quality, high-performance harmonic reducer so that it can be repeatedly positioned in the running project to ensure accuracy.

(3) Good sealing performance: the shafts are completely sealed, suitable for use in harsh environments with high sealing requirements such as dust, oil stains, and harmful gas liquids.

(4) Small in size but can handle heavy load.

2. Advantages of six-axis industrial manipulator:

(1) The six-axis industrial manipulator responses quickly. The robot does not stop or rest during the operation, and improves the efficiency of automated production.

(2) The six-axis industrial manipulator has high accuracy and high-quality impact, which ensure the product quality.

(3) The usage of six-axis industrial robots can reduce labor costs and waste of raw materials.

(4) It is possible to adapt to the production of different work pieces by modifying the program, shortening the product replacement cycle, and investing in application equipment.

(5) Replace workman, work in harsh and hazardous environments.

3. six-axis manipulator requirements for servo

The six-axis galvanized manipulator is mainly composed of 6 sets of servo drives and motors combined with reducers to complete the positioning and rotation of the manipulator. Besides, there are 2 sets of servo drives and motors responsible for feeding. Among them, 1, 2, and 3 axes are composed of Zhishan ZSD-KBS50AB with 180ST-M28415AJ motor, and 4, 5, 6 axes are composed of Zhishan ZSD-KAS20AB with 130ST-M10015AJ motor. The 7 and 8 axes are composed of ZSD-KAS20AB with 110ST-ZM06030AJ motor. The servo drives all work in position mode, and the robot control system sends control signals to servo drives to drive the motors to complete the corresponding actions.

The working scene is shown in Figure 1:

Figure 1

4. Introduction of industry matching performance

The host computer is connected to the servo drive control site. The control mode is pulse + direction in position mode. The host computer sends a position command to the servo drive and the servo drive motor completes the corresponding action. The control wiring is defined as follows:

5. Application of Zhishan servo on the six-axis manipulator

1. Servo drive and motor configuration

2. Related parameter settings

(1) Electronic gear ratio

Control resolution according to specific application requirements

(2) Speed loop integral time constant

When this parameter is reduced, the response can be faster and the speed control error can be less. However, if the setting is too small, vibration and noise are likely to occur. The parameter is larger, the rigidity is worse.

(3) Speed loop proportional gain

When this gain value is increased, the response can be faster. But if the setting is too large, it is easy to produce vibration and noise

(4) Position loop gain

Increase the position loop gain to speed up the system response. Reduce positioning error and shorten positioning time. However, excessive vibration caused mechanical vibration and a system position to overshoot.

(5) Rotational inertia ratio

Ratio of load inertia to motor shaft inertia

(6) low-frequency jitter

Prone to rapid start and stop the robot arm end is positioned so that the prolonged positioning influence production efficiency, the built-in servo control debouncing by PA004 number parameter bottom jitter suppression function is enabled, by PA413 and PA414 disposed jitter Frequency and damping.