The response speed and positioning accuracy of robot joint drive directly determine the flexibility and repeated positioning error of the whole machine motion control.At present,the mainstream solutions generally use dedicated domestic 32-bit MCU as the main control core to balance computing power,peripheral integration and system cost.The MM32SPIN0260 produced by Smart Microelectronics is a special motor processor designed for this kind of scene.Based on this model,Yingshangwei,as a smart agent,launched a 32-bit mcu robot joint motor control scheme on demand.For technical selection or schematic diagram review support,you can contact RAMSUN application engineer for detailed design reference.
First,introduction of domestic 32-bit mcu
The domestic 32-bit mcu MM32SPIN0260 adopts the Arm®Cortex®-M0++core,and the main frequency is configured at 96 MHz.Compared with the general MCU of the same level,its computing power reserve mainly faces the frequent trigonometric functions and matrix operations in the FOC(Field Oriented Control)algorithm.Domestic 32-bit mcu integrates 32-bit hardware divider,hardware squarer and DMA channel,which can significantly reduce the squeeze of interrupt response delay on the closed-loop bandwidth of current loop.In addition,the domestic 32-bit MCU has introduced high-reliability storage technology and added ECC check,which can effectively suppress the interference of single-bit flip on program counters or key parameter areas in the industrial temperature range(-40℃~105℃),which is especially critical for long-running robot joints.
Second,the domestic 32-bit mcu peripheral configuration
The domestic 32-bit MCU is equipped with a 16-bit 4-channel advanced control timer,which supports complementary PWM output,hardware dead zone generation,phase shift control and emergency Brake input.At the same time,it is supplemented by a 32-bit general timer and three 16-bit basic timers,which can be used for encoder pulse capture,speed loop cycle trigger or soft start timing management.The resolution of the advanced timer can reach about 10.4 ns at 96 MHz clock,which is enough to support the small pulse width adjustment in high frequency injection or square wave drive,and is suitable for various control topologies of brushless DC motor(BLDC),permanent magnet synchronous motor(PMSM)and stepping motor.
Third,the characteristics of joint motor control scheme of domestic 32-bit mcu robot
RAMSUN's joint control scheme based on 32-bit mcu chip made in China(MM32SPIN0260)has preset bus voltage monitoring,overcurrent protection comparator and temperature sensor interface in the hardware layer,which reduces the number of discrete components of peripheral protection logic.On the software level,DMA can be used to realize the automatic handling of ADC conversion results and PWM comparison registers,reduce CPU occupancy and leave calculation margin for upper impedance control or force-position mixed control.Compared with the imported alternatives,the domestic 32-bit MCU provides higher peripheral integration at the same main frequency,and the sample supply and FAE response have more geographical advantages,which is suitable for the control scenes of medium power(≤500W)motors such as elbow joint of cooperative robot,leg drive of quadruped robot and AGV steering gear.
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