How to select a driver for the collaboration robot

2020-06-23 17:39:25
Robots interact with the real world in two basic steps: they first sense their surroundings, then use the data they perceive to navigate or manipulate objects by avoiding obstacles. Robot development depends on the driver when it comes to environment navigation and object manipulation. A driver is a component that translates electronic commands into actual operations.

Different applications require different drives, and there are an infinite number of drives to choose from. Various drives commonly used by robots, basic considerations for selecting drives, and how to dock with hardware.

Drive way

Five driving methods commonly used in robot projects:

Dc motor: Motor with output shaft, driven by different grades of DC voltage, used mainly in combination with a moving transmission system such as a track traction device. The output shaft of a DC motor is usually mounted on a pinion, spur gear, or other type of gear, and is usually connected to an electronic speed controller that sets the motor's speed and direction. Like other drivers, DC motors come in a variety of sizes and torques.

· Servo device: including dc motor, output shaft and control circuit, which constitute a whole. Servo systems are usually used to provide rotary motion, continuous rotation servo systems can rotate 360 degrees. There are entry level and robot level servo systems, which we will discuss later.

· Stepper: A device that combines the characteristics of a DC motor and a servo device, usually used in 3D printers and CNC machine tools, to achieve high precision and repeatability, with low output torque of the stepper.

· Linear transmission: it is similar to a servo device, but only provides linear motion. Linear mechanism, such as worm transmission mechanism, is generally adopted.

· Solenoid valves: special linear actuators that provide binary positions (i.e. on/off, etc.). Solenoid valve is usually used for valves, stops, locks and other purposes, or for buttons, generally controlled by an external single chip microcomputer.

The aspects and considerations that drive needs to consider

Robots have many functions and can achieve different purposes in different operating environments, so there are many aspects to consider when selecting drivers.

The choice of driver type depends on the purpose and intended function of the robot. For example, dc motors are commonly used in conjunction with transmission systems for locomotion purposes, while servo devices can be used to provide joints, such as those used in robotic arms.

After determining the driver type, you should also be aware of the associated physical requirements and constraints. First of all, we look at the size and weight of the drive itself to determine whether it is suitable for installation to the corresponding position, and whether the total weight of the mechanism added after installation is appropriate. If the robot arm is too small to bear heavy weight, the heavier driver will be attached to it, and the robot arm will naturally "strike." .

In addition, we also check the digital interface above the driver and the microcontroller. For example, a servo device usually has three wires, including the ground wire, the power cord and the control signal cord. Depending on the power requirements of the driver, we can use the microcontroller directly for power supply, but the microcontroller generally provides only 5V DC output, so sometimes additional power is required. Power consumption usually depends on the torque provided by the driver and the load handled during the operation, which will affect the battery life of the robot. Therefore, we should pay attention to drivers' power requirements." .

"According to the intended use, ensure that the drive is strong enough to accomplish the expected work. For example, when selecting a DC motor, ensure that the DC motor provides enough power to the transmission system to move the robot and the robot load in the operating environment. In addition, when selecting a drive, consider the worst case scenario, such as difficulty in navigating the environment (E. Null "muddy terrain exists in the environment, causing the driveline to skid), or robot overload." .