Microcontroller options for servo control in industrial robots

“The RX72T Group brings leading performance to our extensive lineup of MCUs optimised for industrial robotics and motor control, with built-in IP, safety and security functions, and advanced control,” said Akira Denda, Vice President, Industrial Automation Business Division, Renesas Electronics Corporation.

”The new MCU group extends an easy migration path across the RX family that creates new possibilities for extremely low cost designs in compact industrial robots, and we are excited to accelerate the deployment of these applications to improve manufacturing efficiencies in industrial environments.”

Key features of the RX72T Group of MCUs
Servo systems are becoming increasingly popular and the demand for compact industrial robots is also rising. To implement the complex motions required by industrial robots, high precision control of the position, direction, speed, and torque of the motor is required.

The RX72T MCUs include dedicated accelerator hardware that enables the high speed position control and speed control calculations required for implementing servo motor control in compact industrial robots. This allows the current control loop calculation to be performed in less than 1.5µs (Note 2), providing a new option for users to independently develop servo systems where previously they only had the option of purchasing existing servo systems.

Implementing calculations in software can require excessive computing time. However, completely hardware-based calculations can adversely affect the flexibility to implement unique user control operations. With the RX72T MCUs, Renesas resolves the issue by implementing only the single-precision floating point trigonometric function (sin, cos, arctan, hypot) and a register bank save function in hardware as dedicated IP.

This retains the flexibility while increasing the calculation speed. Furthermore, the register bank save function increases the speed and precision of interrupt handling, improving the device computation performance. The MCUs also include 200MHz PWM inverter control timers with up to four channels of three-phase control, two channels of five-phase control or ten channels of single-phase control.

Customers working with Renesas' Failure Detection e-AI Solutions for motors to improve production and productivity can pair these solutions with the new RX72T MCUs. Characteristic data (current and speed values) that indicate the motor state can be used directly to implement motor control and e-AI-based failure detection with a single MCU. The MCUs also feature hardware-based system failsafe functions and a hardware cryptography module that can be used to encrypt/decrypt communications data.

Renesas provides programmes that implement sensorless vector control and encoder vector control. Renesas provides the Renesas Motor Workbench 2.0 for real time debugging and an RX72T CPU card that supports the 24V motor control evaluation kit.

With the new RX72T MCUs, Renesas offers system manufacturers an extensive lineup of 5V operation motor control MCUs with superlative software compatibility. This provides a smooth migration path from the new high end MCUs out to the RX23T (40MHz), RX24T (80MHz), and RX66T (160MHz) MCUs, offering design flexibility within the RX MCU environment. The RX72T Group is also fully compatible with the RX66T Group incorporating the RXv3 core.