Development trends in the design of robot modules

In the design of industrial robots , it is often divided into the controller system, manipulator (drive system), teaching pendant, vision sensor, final actuator. Robots are very complex systems, there are many design challenges in terms of mechatronics, functionality, electrical aspects. When designing the building blocks of a robot system, it is necessary to understand the requirements in these aspects choose the appropriate design ideas.

Comparison of different controller designs

As we all know, the controller is the core of the robot, which includes motion controllers, internal external communication systems, any potential power levels. Here I would like to mention the potential power level. This concept refers to the fact that if the robot wants to move heavy objects, it needs to exert sufficient force on the motor to complete it. This force is generated by electrical energy provided to the motor the power level. This power affects whether the robot belongs to a high-voltage system a low-voltage system.

There are two approaches to controller design: centralized decentralized. The centralized controller design integrates most of the robot's electronic modules (drive power module, servo drive module, communication module, IO module) into the controller. Most robot manufacturers will choose this design package it as a whole to downstream manufacturers.

( Collaborative Robots , TI)

The decentralized controller design is to move some modules in the centralized controller to the final operating system of the robot, usually the servo drive module, so that the final actuator can support more form factors be more sensitive in cable selection. The trouble with decentralized controller design is that the operating environment of servo drive related electronic equipment is completely different that in the centralized system, generally some systems need to be redeveloped.

Safe compact servo drive planning

Industry 4.0 introduces new standards system requirements for servo drives, so it is important for robot designers to choose solutions that are suitable for current future servo drive needs. The design of power stage modules for current robot servo drives must be compact, efficient fully protected.

One of the functional safety standards for robots, IEC 61800-5-2, defines a safety function called safe torque off (STO) so that the system can safely stop the motor avoid accidental starting. Equipment such as industrial robots industrial mobile robots are generally DC-fed power stages with a typical supply voltage of 48V to 60V, which imposes strong constraints on the system hardware size. The MCU other processor generates PWM, the three-phase power stage gate driver controls the power switch. When the STO command is received an external device, the pulse suppression channel is activated to disconnect the power drive the gate driver to achieve the safety function.

On the other hand, since it involves power switches, it is completely feasible to use SiC GaN to improve motor control performance, which can further improve the power density efficiency of robots. This old topic will be repeated in robot design.

Low latency instant messaging

The more axes a robot has, the higher the network transmission requirements are. Real-time communication interfaces (such as fast serial interfaces Ethernet) are needed to achieve precise safe movement instant communication between all robot systems. It is very necessary for the main processor to support multiple protocols, such as EtherCAT, PROFINET EtherNet/IP, etc., which can only save costs, reduce board space reduce development workload, but also minimize the delays associated with communication between external components the host.

On the other hand, the bandwidth latency of the PHY will also greatly affect the coordination of the robot throughout the movement. Minimizing latency on physical layer devices will significantly reduce the time required for the controller to collect update data connected devices, greatly improving network update time. As long as the bandwidth of the PHY is sufficient, reducing its latency is a very stable way to improve the synchronization of multi-axis systems.

Precise sensor planning

Robot-related sensors cover a wide range, internal voltage, current, motor speed, temperature sensors to external torque sensors, infrared sensors, 3D lidar sensors, visual sensors, IMU, etc.

In terms of internal sensing, almost all sensor materials used in robots are temperature-sensitive components are equipped with thermal compensation. This trend has greatly improved the stability of internal sensing applications eliminated the hidden dangers of motor heating power consumption under heavy loads. In terms of external sensing, as robot technology advances, hybrid sensor technology is also advancing. Combining different sensor technologies can achieve the best effect when deploying robot systems in changing environments.

summary

As manufacturing continues to advance towards a high level of integration at all levels, robots will become increasingly important in performing a wide variety of tasks,  robot developers need to understand the development trends in robot design so that robots can perform precise , safe, cost-effective operations.