Enacting Plant-Inspired Robotics

Abstract

Plants offer a source of bioinspiration for soft robotics. Nevertheless, a gap remains in designing robots based on the fundamental principles of plant intelligence, rooted in a non-centralized, modular architecture and a highly plastic phenotype. We contend that a holistic approach to plant bioinspiration—one that draws more fully on the features of plant intelligence and behavior—evidences the value of an enactivist perspective. This is because enactivism emphasizes not only features of embodiment such as material composition and morphology, but also autonomy as an important aspect of plant intelligence and behavior. The enactivist sense of autonomy concerns the dynamics of self-producing systems (such as plants) that create a distinction between themselves and a domain of interactions that bear on the conditions of viability of the system. This contrasts with the widespread, but diluted notion of autonomy that merely indicates the independent operability of a system for an arbitrary period. Different notions of autonomy are relevant for soft roboticists, for instance, when evaluating limitations on existing growing robots (“growbots”) that take bioinspiration from plants, but depend on a fixed source of energy and material provided by an external agent. More generally, plant-inspired robots serve as a case study for an enactivist approach to intelligence, while, correspondingly, enactivism calls attention to the possibility of non-zoological forms of intelligence embodied in a self-organizing, autonomous system.

Plantness, Animalness, and Humanness: plant placement within animacy and adjacent scales

“…A rare exception is the carnivorous plant, the venus flytrap ( Dionaea muscipula ; Westfall, 2022). Plant mobility is frequently described as ‘movement through growth’ (Lee & Calvo, 2022), and as seen in the description of the plant body, it is difficult to disentangle form from function and life history. Plant form is essentially a depiction of behaviour, capturing what would be a visible or recognizable motion or act from an animal as physical structures (Arber, 1950; Bartušková et al., 2022; Klimešová et al., 2017).…”

“…Autonomy would be formed by any system within an object that processes external stimuli internally and then uses this to respond externally (i.e., the environment; Lee & Calvo, 2022). This definition would classify plants and any robots using a more plant-like processing system as autonomous (Lee & Calvo, 2022).…”

“…Thus, an object would be capable of agency if it is self‐defined as an individual, produces its own activity in the environment, and regulates itself and its activity along certain norms – all easily met by many even relatively simply organisms (Barandiaran, Di Paolo, & Rohde, 2009). Autonomy would be formed by any system within an object that processes external stimuli internally and then uses this to respond externally (i.e., the environment; Lee & Calvo, 2022). This definition would classify plants and any robots using a more plant‐like processing system as autonomous (Lee & Calvo, 2022).…”

Decision Making in Plants: A Rooted Perspective

“…Several proteins known to mediate neurotransmission synaptically in animals have been found in bacteria, throwing light upon the phylogenetic development of neurotransmitters; glutamate and gamma-aminobutyric acid (GABA) are among the chemicals that function, not as mere metabolites, but rather as plant signalling molecules ('biomediators', in plant physiological parlance to distinguish them from animal neurotransmitters). In addition, actin and other cellular motors are also found in plants [18].…”

“…In the aforementioned illustration of root growth behaviour, different volatiles may serve to modulate cellular membrane properties at the root apex, which in turn would explain the differential distribution of the plant hormone auxin that results in the positive or negative tropism exhibited [35]. Yet at a higher level of description, membrane properties will serve to identify common threads, as plant-animal comparative electrophysiology reveals [18]. The response to anaesthesia by both animals and plants, whereby the integrity of the plasma membrane is compromised with the alteration of key membrane properties [59,60] provides a clear-cut illustration of this.…”