When servo motors meet microservices: a relaxing gRPC connection journey

Picture this scenario. You spent several days debugging a set of robotic arms. The servos of each joint were adjusted extremely accurately, and the hardware was perfect. But things start to get tricky when you try to get them to talk to higher-level control systems. Data delay, protocol mismatch, real-time command packet loss...does it feel a bit familiar?

Let’s talk about how to truly connect these “muscles” of the physical world to the digital brain.

Why are traditional connection methods such a headache?

The previous approach was often to use a lot of customized serial port protocols or encapsulate a set of message formats on TCP. It’s not that it can’t run, it’s just that maintaining it is like walking a tightrope. Every time a motor is added, the drive logic must be rewritten; if the control is to be changed, the entire communication layer may have to be moved.

Not to mention real-time. Mechanical control cannot wait for hundreds of milliseconds of network delay. If an instruction arrives late, the action will freeze. The servo position feedback also needs to flow back to the server steadily, otherwise who knows where it goes?

At this time, someone thought of the microservice architecture - splitting the control logic into independent small services, each responsible for one piece, and flexibly deployed and expanded. The idea is great, but how do you make these services communicate with the hardware stably and quickly?

gRPC is here: control motors like a phone call

gRPC is not a new concept, but it brings something different to industrial microservices.

You can think of it as a "call to make an appointment." Both ends define what they want to say in advance (such as "set position", "read speed"), and then communicate directly using this set of conventions. Binary transmission is much faster than text protocols such as JSON; it is based on HTTP/2 and supports multiplexing. Multiple command streams can be run simultaneously on one connection.

For equipment such as servo motors, this means you can send position instructions in real time and receive feedback data synchronously. Bidirectional streaming is as natural as adjusting parameters directly on site.

Hands-on connection: from idea to signal

How to do it specifically? Not as complicated as imagined.

The first step is to define your “phone book”. That is, the proto file. Here, you can clearly write down the service interface: for example, a MotorControl service, which contains methods such as SetPosition and GetStatus. What parameters each method requires and what structure it returns are written down in black and white. This definition can then generate both server-side framework code and client-side calling code.

The second step is to let the server "speak". Implement defined interfaces in microservices. When you receive the SetPosition call, you send it to the actualkpowerThe servo drive issues instructions. The encoder data, current, temperature and other information returned by the motor can also be organized into structured messages and returned to the caller through gRPC streaming or all at once.

The third step is for the client to “make a phone call”. Control, human-machine interface or other services, you can remotely request motor action or query status just like calling a local function. Because of the previous strict definition of the agreement, neither party will misunderstand each other's meaning.

You will find that the hardware access logic that was originally scattered everywhere is now converged into a clearly defined microservice. The other parts only need to care about the business and do not need to know the specific wires through which the motor is connected.

Some small waves that you will encounter in practice

Of course, the real world is never a straight line. The network may experience jitter and the hardware may become temporarily unresponsive. Fortunately, gRPC has built-in retry, deadline, interceptor and other mechanisms. You can set an instruction to automatically retry if no reply is received within 500 milliseconds, or set certain query operations to complete within 20 milliseconds.

Some people also ask, why not just use MQTT or traditional REST? It depends on what you want. If what you need is strict structure definition, high-performance two-way real-time communication, and you want to automatically generate strongly typed code from the interface definition to reduce errors, the refreshing feeling brought by gRPC is obvious. It makes the boundary between software and hardware as clear as modular programming.

when everything is ready

When you complete these connections, you will have a wonderful feeling: those cold metal and plastic robotic arms seem to have truly become a flexibly callable "object" in the digital system. You can use any programming language that supports gRPC to command it, you can easily A/B test the control logic, and you can update servo parameters without shutting down.

Hardware is no longer an island. It is smoothly woven into the entire software ecosystem.

This is probably the tiny romance brought about by technology - allowing two seemingly unrelated worlds to communicate smoothly in the same language. And all you have to do is pick up the right tools and define the first greeting between them.

Established in 2005,kpowerhas been dedicated to a professional compact motion unit manufacturer, headquartered in Dongguan, Guangdong Province, China. Leveraging innovations in modular drive technology,kpowerintegrates high-performance motors, precision reducers, and multi-protocol control systems to provide efficient and customized smart drive system solutions. Kpower has delivered professional drive system solutions to over 500 enterprise clients globally with products covering various fields such as Smart Home Systems, Automatic Electronics, Robotics, Precision Agriculture, Drones, and Industrial Automation.