Robot design - non-standard mechanical design

At present, there are many types of manipulators in the manufacturing industry. There is no unified statement about the classification standards in China, but they are roughly classified according to their usage and driving methods as follows:

1. Classification by usage

The manipulator can be divided into special manipulator and general manipulator

（1）Special manipulator

It is a mechanical device attached to the host with a fixed program and no independent control system. The special manipulator has the characteristics of less movement, single working object, simple structure, reliable use and low cost, and is suitable for large-scale automatic production, such as automatic machine tools, automatic line loading and unloading manipulators and automatic processing centers attached to Tool changer.

（2） Universal manipulator

It is a manipulator with independent control system, variable program and flexible and diverse movements. Within the specification and performance range, its action program is variable, and it can be used in different occasions through adjustment, and the drive system and control system are independent. The general manipulator has a large working range, high positioning accuracy and strong versatility, and is suitable for small and medium batch automated production that constantly changes production varieties. The general-purpose manipulator can be divided into two types: simple type and servo type according to the different control and positioning methods: the simple type controls the positioning in an "on and off" style, and can only be controlled by point position: the servo type has a servo system positioning control system, which can be Point-to-point, continuous trajectory control can also be realized, and the general servo-type universal manipulator belongs to the numerical control type.

2. According to the driving mode

（1） Hydraulic transmission manipulator

It is a manipulator that drives the movement of the actuator by hydraulic pressure. Its main features are: the grasping weight can reach more than several hundred kilograms, the transmission is stable, the structure is compact, and the action is sensitive. However, the requirements for the sealing device are strict, otherwise the leakage of oil will have a great impact on the working performance of the manipulator, and it is not suitable to work at high temperature and low temperature. If the manipulator adopts the electro-hydraulic servo drive system, it can realize continuous trajectory control and expand the versatility of the manipulator, but the electro-hydraulic servo valve has high manufacturing precision, strict requirements for oil filtration, and high cost.

（2）Pneumatic transmission manipulator

It is a manipulator that drives the movement of the actuator by the pressure of compressed air. Its main features are: extremely convenient to use, small output force, rapid pneumatic action, simple structure and low cost. However, due to the compressible characteristics of air, the stability of the working speed is poor, the impact is large, and the pressure of the air source is low, and the grasping weight is generally below 30 kg. Therefore, it is suitable for working in high-speed, light-load, high-temperature and dust-heavy environments.

For example, the use of a rodless cylinder makes this type of manipulator very similar to the mechanical transmission manipulator in terms of structural processing. The difference is that this type of manipulator can only realize the position control of two points, and the grasping Gravity is small.

3. Mechanical transmission manipulator

That is, a manipulator driven by mechanical transmission mechanisms (such as cams, connecting rods, gears and racks, linear guides, screw rods, etc.). It is a special manipulator attached to the work host, and its power is transmitted by the work machine. Its main features are accurate and reliable movement, high frequency of action, but large structure and immutable action program. It is often used for loading and unloading of the working host.

This type of manipulator is currently the most widely used one. We have the following two categories according to the specific characteristics of use:

（1) Combination of gear, rack and linear guide.

（2) Linear module combination

4. Electric drive manipulator

That is, a manipulator with a special structure of an induction motor, a linear motor or a power stepper motor directly drives the movement of the actuator. Because it does not require an intermediate conversion mechanism, the mechanical structure is simple. Among them, the linear motor manipulator has fast movement speed and long stroke, and is easy to maintain and use. There are not many such manipulators at present, but there is a future.

Personally, what I use and design the most is the special mechanical transmission manipulator, that is, the manipulator that is used in conjunction with the CNC machining machine and uses a combination of gears, racks, and linear guides. The design of this type of manipulator, I will Details in subsequent articles.