In the field of Robotics joint servo design, engineers are currently facing two major headaches.
The first is the tight computing power. Running a PID controller used to be enough, but that is no longer the case. Customer requirements are becoming increasingly stringent, necessitating the addition of feedforward compensation and adaptive algorithms to handle nonlinear load variations. Moreover, the current trend is to integrate traditional control algorithms with AI inference. Once these features are stacked, the computing power of the main control MCU is quickly exhausted. Meanwhile, the current loop bandwidth requirement has surged from hundreds of hertz to tens of kilohertz. On the motor side, due to the limited volume of the joint, the winding inductance is steadily decreasing, forcing the PWM carrier frequency to be increased accordingly.
The second is the PCB space. There is only so much room in a Robotics joint, and it also requires hollow wiring, leaving progressively less area for the electronic system. In previous solutions, chips with sufficient computing power had too many peripheral components to fit; those with high peripheral integration lacked sufficient computing power.
Therefore, the market has been looking for an MCU with sufficient computing power, high integration, and the ability to withstand harsh environments.
At the 5th Dishui Lake China RISC-V Industry Forum held today, Fei Zhendong, Product Director of Beijing HPMicro Robotics Semiconductor Technology Co., Ltd., introduced the company's newly mass-produced and released dedicated MCU for Robotics joint CAN communication and motion control—the HPM53M1, which was launched in June this year.
Figure | Fei Zhendong, Product Director of Beijing HPMicro Robotics Semiconductor Technology Co., Ltd.
The core parameters of this chip are as follows: RISC-V core, 480MHz main frequency, with double-precision floating-point and DSP extensions. In terms of memory, it features 128KB each for instruction RAM and data RAM, plus 32KB of AHB SRAM, totaling 288KB, and 1MB of Flash. Actual tests show that the current loop can achieve a cycle of about 1μs. Fei Zhendong believes that this computing power is sufficient for joint control.
Figure | HPM53M1 Architecture Diagram; Source: HPMicro Robotics
In addition, he pointed out that high integration is a standout feature of this chip. It directly integrates a three-phase half-bridge driver with a 150V voltage rating, a 500kHz switching frequency, and an output current of +0.8A/-1.2A, which can directly drive external power MOSFETs. The bootstrap circuit is also built-in with a floating power supply design, saving numerous peripheral components. The analog section provides two 16-bit ADCs with a sampling rate of 2MSPS; two 12-bit DACs at 1MSPS; and two comparators. There are four channels of Op-Amps in total, two for high-speed signal conditioning and two rail-to-rail Op-Amps with a 6MHz bandwidth, all powered by a single 5V supply.
For the encoder interface, it includes a programmable SEI module that supports mainstream absolute encoder protocols such as BiSS-C, Tamagawa, and EnDAT, which can be adapted through programming. The resolver decoder is also directly integrated, eliminating the need for external components. The PWM features two groups of 8 channels, working with the programmable logic block (PLB) for trigger interconnection, offering considerable flexibility.
The communication interfaces include four CAN FD, four UART, three SPI, and four I²C channels, along with a high-speed USB with a built-in PHY for direct connection to a computer for debugging. The package is QFN80, 9×9mm, with a 0.4mm pitch. It supports direct 5V power supply and integrates two 3.3V/500mA LDOs on-chip to power external circuits. The operating temperature ranges from -40 to 105℃, which is adequate for the joint environment.
In addition, HPMicro has developed a 24V joint reference design. The motor has a rated current of 5A, a rated speed of 105RPM, a reduction ratio of 8, and 15 pole pairs. The communication uses CAN and CAN FD, and the application layer protocol is CANopen.
Figure | Joint Solution Based on HPM53M1; Source: HPMicro Robotics
Fei Zhendong stated that the hardware schematics, firmware, USB-to-CAN debugging tools, and host computer software for this solution are all open. Customers can directly start with this solution, eliminating the effort required to build a platform in the initial stages.
It is reported that this chip has been in mass production since June this year. From the perspective of the product line layout, the HPM53M1 fills the gap in CAN communication. Previously, HPMicro already had the HPM5300 series for quadruped joints and encoders, and the HPM6E series with EtherCAT for industrial networking. With the addition of the HPM53M1, both CAN and EtherCAT paths are now covered.
Figure | HPMicro Robotics Will Focus on the Fields of "Motion Control, Real-Time Communication, and Environmental Perception" for Humanoid Robots; Source: HPMicro Robot
At the end of the sharing session, Fei Zhendong revealed that Beijing HPMicro Robotics Semiconductor is a newly established subsidiary this year, dedicated to Robotics-oriented products and technology stacks. In the future, they will likely continue to promote solutions around this platform.