Autonomous shuttle bus with open doors.

Understanding SAE Levels of Automation: From Manual to Fully Autonomous Vehicles  

Autonomous driving is categorized into six levels by the Society of Automotive Engineers (SAE), ranging from Level 0 to Level 5. Level 0 indicates no automation; the driver controls all aspects of the vehicle. Level 1 introduces basic automation like cruise control. Level 2 combines automated functions, but the driver must remain engaged. Level 3 allows for conditional automation, handling most tasks but requiring driver intervention in complex situations. Level 4 vehicles can operate independently in specific conditions, and Level 5 represents fully autonomous vehicles, requiring no human input under any driving scenario. 


Why are HMIS needed in autonomous driving?  

Currently, most autonomous vehicles operate at Level 3. This “conditional driving automation” means the vehicle can handle itself under certain conditions, allowing the driver to disengage from active control, but still requires human intervention in more complex or severe scenarios. For instance, a vehicle with a “conditional driving automation” (level 3) can be a traffic jam chauffeur on the highway. Indeed, the vehicle accelerates and decelerates autonomously keeping a safe distance according to the density of the traffic jam. Similarly, the steering wheel follows the trajectories of the lane by itself. However, if the lines are not drawn on the track, the driver must regain control of the vehicle. This necessity highlights the critical role of Human Machine Interfaces in these vehicles. Even as they navigate autonomously, situations arise—like severe weather or unexpected roadblocks—where a human must take over. 

Connected autonomous vehicles on a busy highway.

In these instances, the vehicle’s HMI becomes crucial. These interfaces, that are often hidden in a service unit or in an engineer panel in the form of a joystick, allow the vehicle to be controlled manually. This manual intervention is essential for tasks such as parking or navigating around unforeseen obstacles when autonomous features temporarily fall short.

The role of an autonomous vehicle operator becomes vital in these scenarios to ensure safety and efficiency. It’s also crucial to consider the dangers of self-driving cars, such as system failures or hacking, which necessitate reliable HMIs for human intervention. 

Intersection with autonomous vehicles and integrated traffic systems.

APEM’s HMIs for Autonomous Vehicles 

At APEM, we are committed to the challenges of new forms of smart mobility solutions and public transport. We aspire to build the mobility experience of tomorrow. Consequently, we supply robust components tailored for these autonomous systems. Products like the CW, IP, and XA series are engineered to meet the specific demands of autonomous vehicles. With its hall effect, the CW series provides proportional control in one miniature axis whereas the IP series has an operating temperature ranging from -45°C to +85°C and a service life of 500,000 cycles. Meanwhile, the XA series from IDEC, an E stop, is equipped with new technology called safe break action. The safe break action design reverses the energy direction and uses the spring-pressure to assure that the NC contacts will open if the emergency stop switch is damaged or the contact blocks separate due to excessive force. Overall, these components combining ergonomics and robustness ensure reliability and precision in high-stakes environments, contributing to the future of autonomous vehicles