Chapter 3 Foundations of Survivability in Autonomous Systems 55
3.8 Incorporating survivability into autonomous systems
3.8.4 Extension of needs to autonomous systems
Maslow’s Needs Theory and others such as Alderfer’s ERG Theory have identified the differentneedsthat account for motivation in humans (section 3.6.2). In much the same way that human beings possess differentneedsand are motivated by them, autonomous systems can be regarded as possessing needs pertaining to their own survival and successful operation (Figure 3.10), i.e. a mapping TN : NBio → NAS from the needs NBio of biological systems toNAS, i.e. those of autonomous systems. The justification is that autonomous systems are designed with specific mission objectives that must be performed within operational and temporal constraints. In order to achieve these objectives, an autonomous system is required to make decisions that maximize the possibility that it can survive and complete its mission.
To appreciate this further, in the case of an autonomously guided vehicle, this may entail safe navigation through different terrain while guiding itself around obstacles which may impede its progress (Seetharaman et al., 2006). In addition, the ability to conserve power would prolong its operation (Bruch et al., 2005). Furthermore, the ability to maintain the integrity of the platform (such as remaining on level ground and not overturning, as in the case of Figure 2.2(b)) would assist the vehicle in safeguarding its viability for performing its mission objectives. These requirements are akin to those described in section 2.3.1.
In the same manner that human needs can be classified into a hierarchy, the following shows how the same needs in human beings can be transformed to the
Safety
Physiological Social Esteem Self-Actualization
Safety
Sustenance Awareness Accomplishment
Cognition Maslow’s Hierarchy
of Needs Theory
Autonomous System Survivability Needs
T N
Mapping Function
Figure 3.10: Mapping from Maslow’s Hierarchy of Needs to Autonomous System Survivability Needs.
autonomous systems perspective, by looking at the contextual meaning of each human need, reinterpreted as theneedof an autonomous system (Figure 3.10):
Sustenance - (corresponding to human physiological needs). The need for power, electricity, fuel, are analogous to a biological system’s need for maintaining homeostasis.
Safety - The need for maintaining and ensuring proper functioning of components and the proper functioning state of all software components. This involves keeping the system away from dangerous situations, e.g. obstacles, which is analogous to the need for safety and shelter in biological systems.
Awareness - (corresponding to social needs). The need to interact within the same shared workspace as other autonomous (possibly human) entities, and being situationally aware of changes in the same environment. This is analogous to the socialneedsor the need for a sense of belongingness in biological systems.
Accomplishment - (corresponding to esteem needs). The need to achieve the tasks that have been assigned to the system, namely to achieve the missions which the autonomous systems is designed to perform. In the case of a human being, the accomplishment of goals increases self-esteem and the sense of achievement.
Cognition - (corresponding to the higher needs in Maslow’s Hierarchy). The need for adaptation, learning, and understanding, i.e. curiosity for exploration, experimen- tation, and interaction with the world.
The above autonomous systemneedsare reinterpretations of the corresponding human needs, illustrating the ease with which this can be done. From this illustration, several principles on the development of intelligent autonomous behaviour can be acquired:
PRINCIPLE3.1 The requirements for autonomy, from a survivability perspective, can be represented as a set of needswith different priorities.
A mapping is possible between human needs and autonomous system needs. These needs can be represented in the form of a hierarchy, much as in the case of Maslow’s Hierarchy of Needs. Whileneedsmotivate different behaviour, different behaviours may have different levels of impact (contribution or detriment) onneeds fulfilment.
PRINCIPLE3.2 When lower level (i.e. basic) needsare unfulfilled, greater attention is placed on satisfying these lower levelneedsrelative to higher levelneeds.
The ability of an autonomous system to deal with perturbations is triggered by the lower levelneeds when theseneedsare violated. For instance, the presence of a river across the path of an unmanned ground vehicle frustrates the autonomous vehicle’s attempt to fulfill its need to arrive at the destination. It may search for another path, while remaining connected to the human operator or other robots (i.e. theneedto co-exist), avoiding one or more wheels getting stuck in a ditch (i.e. theneedto maintainsafety) or run out of power (i.e. thesustenance need). The lowest unsatisfiedneedwould be the most active. Lower levelneedshave shorter horizons for fulfilment deadlines, and tend to have greater urgency in the case where they are unfulfilled.
The manner in which lower unsatisfied needs are activated in lieu of higher needs which are temporarily forgone is similar to subsumption-type architectures (Brooks, 1991). The distinction here is that for needs satisfaction, an explicit knowledge representation (in this case, a model ofneedsand how they can be fulfilled) is expressedly required. However, the exact nature or form of each need, and whether these needs follow the same sequence as delineated above, are inconsequential; For the purpose of identifying principles for theSurvivability Framework, it suffices that this exercise shows the plausibility of definingneeds for artificial systems, i.e. it is conceivable that autonomous systems possesses needs which guide their behaviour.