Behind the robotics boom, ZeroErr raises funds to build the parts that power it

Until recently, investors had been diving headlong into the robotics space, especially those delving into home- and consumer-focused use cases. Suddenly, deals that had dragged on for months were closing overnight. Investors who once hesitated are now charging ahead with conviction.

While growth in humanoid robot development is starting to plateau, attention is shifting to the vast and complex supply chain behind these machines. But that door too is already narrowing to a slit. Over the past two years, as the humanoid robot wave simmered beneath the surface, upstream suppliers quietly emerged as valuable, and now expensive, targets.

One such example is ZeroErr. Founded in 2016, the company manufactures high-reliability, high-precision components critical to robot function, specifically robotic joints and encoders. In 2018, leveraging its proprietary high-precision encoder, ZeroErr came up with a standardized integrated joint module design and moved it into mass production. Since then, it has raised multiple eight-figure RMB funding rounds and today boasts a valuation well north of RMB 1 billion (USD 140 million).

Even before this boom, there was strong demand for robotic joints across multiple fields from surgical and service robots in healthcare to industrial robots in automotive and 3C electronics.

“We started shrinking joint sizes well before humanoid robots got hot,” said ZeroErr founder Jia Xiqing in an interview with 36Kr. “It’s not just about the humanoid market. Other sectors also demand increasingly specialized solutions. Take laparoscopic surgical robots, for example: they enable faster, more precise surgeries with smaller incisions and shorter recovery times. They also enable remote surgeries, bringing expert care to rural areas.”

ZeroErr’s story mirrors that of many players in the supply chain. Rather than pinning their hopes entirely on the still-nascent humanoid robot segment, they are earning steady revenue from more established verticals.

Today, ZeroErr’s joint modules are used across a wide range of robotic applications. Its client list includes more than 2,000 robotics and tech firms globally, including automakers. To date, the company has shipped nearly 50,000 joint modules, leading the industry in sales volume.

Jia said that the biggest contributors to the company’s revenue are joint sales in industrial, logistics, and medical settings, which together account for nearly 50% of total income. Sales to the humanoid sector now make up about 15%, a figure that has grown rapidly in the past two years.

The company’s greatest strength, in Jia’s view, is its stability. ZeroErr relies on its core clients for baseline revenue, while the sector offers an uncertain but potentially vast upside. According to data from Gonyn.com and GGII, demand for robotic joint modules in China reached 2.24 million units in 2024, and is projected to rise to 4.82 million units by 2030, with the market size possibly exceeding RMB 68.9 billion (USD 9.6 billion).

“At the moment, our humanoid clients primarily want joints that are smaller, lighter, and more powerful, with greater reliability,” Jia said. “As humanoids move into consumer-facing roles, cost reduction becomes essential. That’s our product team’s main priority right now. We believe there’s still enormous room for growth in the joint market as robots become part of daily life.”

Harmonic and planetary gear joints will coexist for the long haul

Whether it’s industrial robots handling inspections and heavy lifting on factory floors, service robots offering directions in malls, or humanoid robots performing on stages, every fluid and precise movement depends on high-performance joints.

A robot’s precision, speed, and agility all hinge on joint quality. Due to differing operational environments and tasks, various robots require different joint configurations and core components. Contemporary designs tend to use modular power units that integrate motors, reducers, drivers, encoders, and other sensors.

ZeroErr’s joint modules are composed of key parts like absolute encoders on both the motor and output ends, frameless torque motors, harmonic reducers, holding brakes, servo drivers, and torque sensors.

The encoder acts as a robot’s angular feedback system, constantly measuring joint positions and sending updates to the control system.

In its flagship eRob series, ZeroErr equips both the motor and reducer ends with absolute encoders featuring seven-arcsecond repeatability and 15-arcsecond absolute accuracy. This enables full closed-loop position control, offsetting backlash, wear, and manufacturing deviations from the reducer. According to the company, these are the most precise and responsive harmonic joint modules available in the industry.

For instance, surgical robots require extreme precision in repeatability, power efficiency, safety, and torque control, since they often operate inside the human body.

For humanoid robots, ZeroErr’s encoders enable highly accurate joint control, which is essential in tasks like material handling and component assembly on automotive lines. The result: improved operational accuracy, productivity, and quality.

Currently, limb and torso structures of humanoid robots use three primary transmission mechanisms: harmonic reducers, planetary reducers, and planetary roller screws. The latter is used for linear motion, while harmonic and planetary reducers handle rotational movement.

Planetary reducers are more affordable and capable of handling higher torque, making them ideal for large-scale deployments. However, they typically offer lower gear ratios in a single stage and are better suited for heavy-duty but less precision-sensitive applications.

“One major advantage of planetary reducers is that China already has a mature industrial base for them,” Jia said. “They are widely supported by local machining capabilities. Plus, their simple structure and design flexibility make it easy to integrate with other joint components.”

Still, humanoid robots are a different beast. With over 40 joints and a need for compact, lightweight designs, they demand high power density in a small package. That’s where planetary reducers can fall short. Harmonic reducers, on the other hand, excel. They offer greater reduction ratios in tight spaces and enable finer motion control thanks to smaller backlash.

ZeroErr specializes in harmonic reducer-based joints. “They are compact and lightweight, perfectly suited for humanoids,” Jia said. “Harmonic drives also have very high transmission accuracy and large single-stage ratios, which are essential for precision joint motion.”

That said, harmonic drives still face limitations. They require expensive manufacturing equipment, tight tolerances, and advanced expertise in materials, heat treatment, and gear design. For now, these constraints hinder cost reduction and limit scale.

“China is catching up fast to international standards in harmonic drives,” Jia added. “But deep customization, like what’s possible with planetary-based joints, is still hard to achieve. It’s a chicken-and-egg problem: customization requires volume orders, but volume depends on access to customized prototypes. Harmonic joints cost around five times more than planetary ones, so scaling remains a challenge.”

In Jia’s view, neither approach is definitively superior. Harmonic and planetary drives offer different strengths in lifespan, shock resistance, noise, and failure modes. As a result, both are likely to coexist, with optimal use determined by the demands of each humanoid application.

Standardized yet flexible, with broad applicability

Citing a 2024 report on humanoid robot development, 36Kr postulated that cost reduction in humanoid robot manufacturing will occur in three major phases: small-scale production (1,000 units) can lower costs by 20–30% to around USD 100,000 per unit; at 10,000 units, costs drop by 50% to USD 50,000; at hundreds of thousands of units, costs could fall by 70–80%, reaching USD 20,000–30,000.

If mass production takes off, demand for core components like joints will skyrocket. Scale matters, and ZeroErr is preparing accordingly. To meet diverse needs across industries and applications, the company has launched multiple joint models including the straight eRob I-type and Corner T-type series.

The eRob modules vary widely in size and torque capacity. The smallest model has a diameter of just 70 millimeters with a maximum torque of 70 newton-meters, while the largest stretches to 170 mm and supports up to 1,180 Nm. Compared to peers with similar torque ratings, ZeroErr’s modules are significantly more compact.

This small-form, high-torque design has real-world advantages. In warehousing, for example, smaller joints allow robots to operate smoothly in tight quarters. In surgery, they enable robotic arms to work closer together, reducing incision size. For humanoids, they bring form factors ever closer to the proportions of the human body.

For downstream clients, ZeroErr’s standardized yet diverse joint lineup simplifies the fabrication process. Developers can skip hundreds of hours of selecting, sourcing, and assembling mechanical and electronic parts, and focus instead on developing full robot systems and applications.

Meanwhile, the trend toward domestic sourcing is gaining traction. The industry’s dependence on imported joint components is gradually eroding.

Except for certain chips, all of ZeroErr’s core parts are now either domestically developed or sourced from local supply chains.

“Full localization is our goal,” Jia said. “We’ve already begun testing domestic chips. Before long, we won’t have to worry about supply chain choke points.”

The company has also invested in infrastructure. It operates multiple workshops for five-axis precision machining, quality inspection, and precision assembly. Each joint module is fully tested for backlash, rigidity, noise, precision under load, and vibration. After assembly, modules undergo simulation testing to ensure performance under varied industrial conditions, helping to minimize market failures.

The sudden boom in humanoid robotics has propelled component suppliers that once seemed obscure into the spotlight. But for firms like ZeroErr, long-term survival won’t depend on humanoid robotics alone. Enduring revenue still comes from proven customers in established markets. Serving them remains the company’s most critical mission.

KrASIA Connection features translated and adapted content that was originally published by 36Kr. This article was written by Huang Nan for 36Kr.

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