5 Key Factors to Consider in Motion Control Applications

When designing an application involving motion control, there are numerous factors to take into account. These include selecting the right motor type, choosing a suitable motor driver, obtaining feedback from the system, synchronizing movements, and enabling communication between different system components. All these aspects must be addressed to develop a highly reliable motion control system.

Below are the key factors to consider:

1.Selecting the Appropriate Motor Type

In any motion control application, the first step is to choose the right motor type for the specific use case. The most common motor types are stepper motors, brushless DC motors, servo motors, AC synchronous motors, and AC induction motors. Selection is typically based on the motor’s inherent torque and speed characteristics.

Motor Torque and Speed Characteristics

Motor manufacturers can certainly assist users in selecting the correct motor, but it is still essential to understand basic motor knowledge before making a final decision.

Basic Knowledge

In closed-loop control systems, various sensing components are used, such as encoders, linear scales, resolvers, and tachometers. For closed-loop motor control, incremental encoders provide position signals relative to the initial position, while absolute encoders deliver the absolute position of the shaft and allow for position homing during device startup.

2.Understanding Communication Buses

Communication between the controller and driver can be achieved via analog signals, digital signals, or dedicated communication buses. Among these, communication buses are responsible for transmitting motion commands from the controller to the driver.

Several factors need to be considered when selecting a communication bus, with the distance between the controller and driver and potential environmental interference being critical. For example, in high-interference environments, communication buses like EtherCAT are more suitable than analog signals. However, this selection is also highly dependent on the compatibility between the controller and driver—compatibility cannot be overlooked, especially when using controller and driver products from different manufacturers.

3. What is Synchronized or Coordinated Motion?

An indispensable step in the design process is evaluating application requirements and motion trajectories to determine in advance whether multi-axis synchronization or coordination is needed. The most basic method for multi-axis synchronized motion is to generate a motion vector and then calculate the components for other axes, thereby synchronizing these values to each corresponding motion axis. Another method is to use electronic gearing, where one motion axis is designated as a follower of another to achieve coordinated motion. Follower trajectories are typically derived by scaling the trajectory of the master setpoint.

In some applications, cameras or sensors are used to synchronize the entire motion process. For instance, a system designed for HMI testing needs to synchronize feedback values from pressure sensors to the probe to adjust the precise contact pressure, ensuring the normal operation of the entire system. In a finished product inspection system, the camera acts as the master device that controls and synchronizes the entire system.

4.Defining the System Architecture

Once the hardware and synchronization method are determined, it is necessary to decide where to execute control commands. There are two common system architectures: single-node control (where control commands are centralized in one device) and multi-node control (where control commands are distributed across various nodes).

The first approach, single-node control, can be implemented using a central control system, such as an IPC equipped with a motion control card. Such systems are easy to set up and configure but have limitations in scalability—for example, they are restricted by the number of PCI slots. The second approach, multi-node control, requires the use of multiple sets of intelligent drivers.

5. Choosing the Right Development Software

Some motion control systems can operate independently, while others need to be integrated with other systems, the most common integration being with vision systems. In such cases, proficiency in development software is essential. Most functions in development software are modular, allowing users to replace similar products from different brands without making extensive modifications to control commands or code. In addition, the software can simulate the environment to test the entire motion process, enabling most of the programming and motor parameter adjustments to be completed before physical implementation.