Enhancing Safety in Autonomous Mobile Robots

Summary

Robots have been introduced to industrial workplaces to help improve productivity and efficiency. As Industry 4.0 transitions to Industry 5.0, industrial manufacturers have been leveraging AI and other advanced technologies as they strive to improve competitiveness with a focus on a human-centric approach and sustainability. This trend of enhancing human-robot interactions has driven a significant rise in the adoption of autonomous mobile robots (AMRs) as organizations seek to improve efficiency and quality.
 
AMRs require complex hardware and software systems to work side-by-side with human operators in modern manufacturing or warehouse facilities. Because robots can generate large forces and move at a faster speed, they may bring certain risks, such as injuring human co-workers in an unintended collision. These risks must be carefully managed, both in the set-up of the relevant operational processes, and in the design of the robots themselves.

The rise of automation alongside humans

Industrial adoption of robots began in earnest during the computer era of the 1960’s and there are an estimated 3.4 million industrial robots in use today. Over the last two decades, advancements in digital technologies have led to the emergence of collaborative and mobile robots capable of navigating complex environments and working in teams to complete tasks.
 
As industrial automation evolves from Industry 4.0 to Industry 5.0, levels of human-machine interaction will drive further demand for AMRs, with the market forecast to triple its 2022 value of US$1.02 Bn by 2030, to reach US$3.13 Bn. (Figure 2).

The key subsystems within AMRs

AMRs use multiple sensors, AI and advanced algorithms to interact with their environment, making decisions, detecting obstacles and safely cooperating with human operators and other machines.
 
The functional block diagram below, Figure 3, represents a typical design for an AMR system with the essential subsystems including–motion control, sensing, lighting, power and charging, and communications.
 
Let's focus on sensing, motor control and lighting subsystems.

Sensing subsystems

Sensors enable robots to adapt to their operational environment, making decisions based on real-time data. Sensor types include imaging, ultrasonic, infrared, inductive and inertial sensors, which are used to enhance navigation and safety for the robots. Overcoming situational complexities such as loading ramps may require different types of sensor and sensor fusion merges the data from multiple sensors.

Motion control subsystems

Robots must be capable of repetitive and precise motion. Most moving parts, including arms and traction systems rely on brushless DC (BLDC) motors, controlled by complex algorithms. Typically, BLDCs are controlled by variable-frequency drive (VFD), which use discrete components such as MOSFETs, IGBTs, gate drivers, and diodes. Power integrated modules (PIM) and intelligent power modules (IPM) offer a higher level of integration, reducing part-count and saving space.
 
onsemi offers both discrete components and modules, including the NCD83591 motor driver, an easy-to-use, 60 V multi−purpose 3−phase gate driver with a high gain-bandwidth current sense amplifier, making it ideal for robotic motor control. This gate driver is packaged in a small footprint QFN28 (4x4 mm) with a high level of integration and ideal for overall BOM optimization. onsemi also offers the NCS3210 and NCV77320, inductive position sensors, used in motion control systems to measure the rotation of wheels or other moving parts.

Lighting subsystems

Lighting technology is used to light the way, helping AMRs navigate and operate, as well as communicate with others by signaling and indicating their status and intent. LED lighting technology is selected for its performance characteristics, including brightness, color temperature and power consumption. The LED lightning solution can be built up using a variety of components not limited to LED drivers, buck or boost voltage converters and power MOSFETs.
 
LED controllers and drivers are components which monitor the current flowing in LEDs and enable them to emit light of a specific intensity and wavelength. LED driver circuits use high-side and low-side power MOSFETs to switch on and off the LED current and protect against overvoltage and overcurrent conditions while also ensuring the stability of the LED driver circuit. The NVC7685 has twelve linear programmable constant current sources with a common reference, allowing 128 different PWM-adjustable duty cycle levels. This linear LED driver is designed for use in the regulating and control of LEDs, ideal for AMR and automotive applications.
 

Conclusion

Unlike the previous generation of robots, which were separated from the human workforce, these modern robots must be designed to co-operate safely and prevent physical harm and damage. A new generation of robotic solutions is transforming a wide range of industries, including manufacturing, e-commerce, healthcare and transportation where competitive pressure demands efficiency without compromising quality and safety. These flexible and customizable robots are designed to work alongside humans, performing repetitive tasks which demand precision, enabling operators to focus on higher-value activities.