Real-time behavior-based control

22 February 2011

share this:

Using behavior-based controllers, robots are theoretically able to rapidly react to their environment. This is typically done by having several behaviors, that map sensory input to actuator commands, run concurrently on the robot. A hierarchy then determines which behavior has access to the actuators.

If your robot needs to navigate a room, you might implement a trajectory planning behavior and a simple obstacle avoidance behavior with high priority to avoid any accidents. If the robot only has one processor, then both behaviors might run in “parallel” as threads. However, if one of your behaviors entails heavy processing, it might hog all the CPU power and impeach the high-priority behaviors from being executed at the right time. In the example above, this might lead to the robot crashing into obstacles. One solution consists in increasing the processing power although this might be incompatible with the size and cost constraints of your robot.

As an alternative, Woolley et al. propose a “Real-Time Unified Behavior Framework” to cope with real-time constraints in behavior-based systems. The framework allows time-critical reactive behaviors to be run at a desired time and in a periodic fashion. Instead, demanding processing tasks that are not critical to the safe operation of the robot are executed whenever possible. This is done by moving time-critical behaviors out of the Linux environment (which can not execute real-time tasks) and into an environment managed by a real-time scheduler.

Real-time tasks bypass Linux and run on the real-time scheduler.

Experiments were conducted on a Pioneer P2-AT8 robot equipped with 16 sonars, odometry, a SICK LMS200 laser scanner and a 1294 camera. The robot was programed to follow an orange cone through a hallway while avoiding obstacles. Results show that the robot was able to meet hard real-time constraints while running computationally demanding processes including FastSLAM.

Sabine Hauert is President of Robohub and Associate Professor at the Bristol Robotics Laboratory
Sabine Hauert is President of Robohub and Associate Professor at the Bristol Robotics Laboratory

Related posts :

Call for robot holiday videos 2022

That’s right! You better not run, you better not hide, you better watch out for brand new robot holiday videos on Robohub!
02 December 2022, by

The Utah Bionic Leg: A motorized prosthetic for lower-limb amputees

Lenzi’s Utah Bionic Leg uses motors, processors, and advanced artificial intelligence that all work together to give amputees more power to walk, stand-up, sit-down, and ascend and descend stairs and ramps.

Touch sensing: An important tool for mobile robot navigation

Proximal sensing often is a blind spot for most long range sensors such as cameras and lidars for which touch sensors could serve as a complementary modality.
29 November 2022, by

Study: Automation drives income inequality

New data suggest most of the growth in the wage gap since 1980 comes from automation displacing less-educated workers.
27 November 2022, by

Flocks of assembler robots show potential for making larger structures

Researchers make progress toward groups of robots that could build almost anything, including buildings, vehicles, and even bigger robots.
25 November 2022, by

Holiday robot wishlist for/from Women in Robotics

Are you looking for a gift for the women in robotics in your life? Or the up and coming women in robotics in your family? Perhaps these suggestions from our not-for-profit Women in Robotics organization will inspire!
24 November 2022, by and

©2021 - ROBOTS Association


©2021 - ROBOTS Association