Safer Robots, Happier Humans: How Sensor-Free Tech Could Revolutionize Workplace Safety
"Unlock the potential of collaborative robots with groundbreaking sensor-less force detection for safer, more intuitive human-robot interactions."
Imagine a factory floor where robots and humans work side-by-side, seamlessly collaborating to assemble products, move materials, and perform intricate tasks. This vision of human-robot collaboration (HRC) is rapidly becoming a reality, promising increased efficiency, improved safety, and a more engaging work environment. But to truly unlock the potential of HRC, we need robots that can sense and respond to their human partners in a safe and intuitive way.
Traditionally, achieving this level of responsiveness has required equipping robots with a variety of external sensors, such as force/torque sensors, tactile sensors, and vision systems. These sensors provide robots with the data they need to detect human presence, understand human intent, and react appropriately to unexpected contact. However, adding these sensors can be costly, complex, and difficult to integrate into existing robotic systems.
Now, a groundbreaking new approach is emerging that eliminates the need for external sensors altogether. This sensor-less force detection technology uses sophisticated algorithms and dynamic models to allow robots to "feel" their environment and detect external forces without relying on additional hardware. This innovative approach promises to make collaborative robots more accessible, affordable, and adaptable, paving the way for a new era of human-robot collaboration.
Estimating Contact Forces Without Sensors
Research on physical human–robot interaction is developing sensorless methods for estimating unknown contact forces in heavy-duty industrial robots. One 2021 study combines state observers with neural-network approximation of friction, while a 2025 paper proposes a transformer-based learning method for interaction-force estimation. Other work emphasizes that sensorless approaches can avoid the high cost of installing force sensors while estimating interaction force and torque.
Model-Based Estimation and Its Limits
Industrial robots without built-in force/torque sensors commonly rely on inverse dynamics to estimate external forces. Sensorless approaches also use internal signals and methods such as disturbance observers, adaptive sliding-mode observers, and actuator measurements. However, their accuracy remains constrained by system-model quality, state estimation, and sensing fidelity. Existing validation has often focused on free-space motion and simple contacts rather than high-precision assembly tasks.
From Automata to Industrial Robots
Accounts of robotics trace its origins to automata in the ancient world and Renaissance-era designs. During the Industrial Revolution, advances in structural engineering and electrical control enabled machines powered by small motors. Industrial robotics then evolved substantially after World War II alongside advances in computing, eventually transforming manufacturing workplaces.
Why Sensor-less Force Detection is a Game-Changer for Industrial Robots
The core idea behind sensor-less force detection is to leverage the robot's existing internal sensors – such as joint position sensors and actuator current/torque sensors – to infer information about external forces acting on the robot. By analyzing the data from these sensors in conjunction with a detailed dynamic model of the robot, it's possible to estimate the magnitude and direction of external forces without the need for dedicated force sensors.
- Dynamic Modeling: A detailed dynamic model of the robot is created, capturing its inertial properties, friction characteristics, and other relevant parameters.
- Parameter Identification: The parameters of the dynamic model are identified using advanced algorithms and experimental data.
- Torque Residual Analysis: The difference between the predicted torque (based on the dynamic model) and the measured torque (from the robot's internal sensors) is analyzed to estimate external forces.
- Threshold Detection: A threshold is set to distinguish between normal operating forces and external forces that may indicate human contact.
Sensorless Force Observation with Compliance Control
A 2025 paper presents a model-based scheme for controlling an industrial robot during physical human–robot interaction without external sensors. Its architecture has two main modules: force observation and compliance control. Together, these modules represent a current research direction in which robots estimate interaction forces internally and adjust their behavior to support physical interaction.
Accuracy Remains a Central Concern
Sensor-free force estimation should not be treated as universally reliable. Performance may vary with the robot, task, operating conditions, and quality of its internal model and measurements. This makes validation in realistic workplace conditions essential before such systems are relied upon for safety-critical interaction.
Cost Versus Direct Measurement
Sensorless systems may reduce hardware cost and avoid the installation of dedicated force or tactile sensors. Direct sensors, however, provide a different measurement pathway and may be preferable where dependable contact information is critical. The practical choice therefore depends on the required accuracy, task complexity, and consequences of estimation error.
The Future of Human-Robot Collaboration is Sensor-Free
Sensor-less force detection technology has the potential to revolutionize human-robot collaboration, making industrial robots safer, more adaptable, and more accessible. By eliminating the need for external sensors, this innovative approach reduces costs, simplifies integration, and opens up new possibilities for collaborative manufacturing, assembly, and other industrial applications. As the technology continues to develop and mature, we can expect to see sensor-less force detection playing an increasingly important role in the future of human-robot collaboration, creating safer and more efficient workplaces for everyone.
A Promising but Conditional Safety Tool
Sensorless robotics could make physical human–robot interaction more accessible by combining internal measurements, observers, and learned models. The research points to meaningful potential for lower-cost force estimation without dedicated hardware. Its safety value remains conditional on accurate estimation, appropriate control, and testing beyond simple laboratory contacts.
AI, Collaboration, and Sensor Integration
Recent industrial-robotics reviews identify automation, artificial intelligence, human–robot collaboration, and sensor integration as important forces reshaping industry. Siemens is examining technology trends and scenarios that could influence robotics over the next decade. The International Federation of Robotics likewise identifies technological innovation, market forces, and new business fields as drivers of robotics demand in 2026.
Safety Depends on the Whole System
Sensor-free safety is not only a matter of choosing an estimation algorithm. It also depends on robot behavior, control design, task conditions, validation procedures, and how workers interact with the system. A broader deployment approach is therefore needed to ensure that reduced hardware requirements do not create overlooked operational risks.
Making Contact Safer for Workers
External torque sensors can provide reliable measurements, but they are described as expensive and vulnerable to impacts. Deep-learning research therefore explores estimating external torques from internal signals such as joint states and current measurements. For workplace interaction, this approach could support safer robot responses while reducing reliance on exposed sensing hardware.