Distributed Multi-Axis Servo Drive Over Fast Serial Interface – Reference Design

The TIDM-02006 reference design from Texas Instruments shows an example of distributed multi-axis servo drive over Fast Serial Interface (FSI) using C2000 real-time controllers. Multi-axis servo drives are used in many applications such as factory automation and robots. Target applications for the TIDM-02006 include industrial motor drives, factory automation and control, and ac drive control modules.

The cost per axis, performance, and ease of use are always high concerns for such systems. FSI is a cost-optimized and reliable high- speed communication interface with low jitter that can daisy-chain multiple C2000 devices.

In this design, each F28004x device serves as a realtime controller for a slave axis, running motor current control loop. A single F2838x device runs position and speed control loops for all axes. The same F2838x also executes main axis motor control plus EtherCAT communication, leveraging its multiple cores. The design uses TI's existing EVM kits, the software is released within C2000WARE MotorControl SDK.

The TIDM-02006 reference design includes the following elements:

1. Master node consists of one controller, one high voltage inverter, and one PM motor with incremental encoder. TMS320F28388D functions as the controller, which samples all the voltage and current inputs and generates the correct pwm signals for inverter. The controller also exchanges data as lead with slave controllers via FSI, and communication with EtherCAT master on PC.
2. Four slave nodes, each node consists of one controller, one low voltage inverter, and one PM motor with incremental encoder. TMS320F280049C functions as the controller, which has all the voltage and current sensing inputs and generates the correct pwm signals for inverter. The controller also receives and transmits the data with master controller via FSI.

Summary of Features

• Demonstrates high-speed communication using fast serial interface (FSI) for real-time speed, position and current command data communication between multiple devices.
• Implements position and velocity control loops for all slave axes on F2838x based master node, torque/current loop on each F28004x based slave node.
• Up to 16 axes can be managed with one F2838x. Start and stop of each axis can be controlled simultaneously. Achieves high bandwidth and higher precision control of distributed multi-axis motor drive system.
• Uses F2838x multi-core functionality to implement speed and position control and data exchange with all slave nodes over FSI, and executes main axis motor control and EtherCAT communication with PC.
• Integrated SFRA tool on both F28004x and F2838x to support online speed and current loop tuning.
• Incremental system builds to verify the different software modules step by step.