Active modification of the environment by a robot with construction abilities

Abstract

Field robots are widely used to accomplish a variety of tasks in many different fields. However, setting of the locomotive ability of these robots at the design phase may prevent the traversal of unknown rough terrain. To address this shortcoming of existing robots, we designed a robot that is able to modify its environment by using polyurethane foam to construct auxiliary structures to facilitate movement across previously impassable terrain. Two robots were implemented with the ability to eject one-and two-part polyurethane foam, respectively. First, we investigated the specifications of the different types of polyurethane foam, specifically the volume expansion and curing time thereof. Two-part polyurethane foam cures in approximately 2 min, compared with 1 h for the one-part foam, but requires more accurate spraying, and its vertical expansion needs to be considered for accurate construction of auxiliary structures. The performance of each robot was tested in two experiments in the field. The first involved filling a deep ditch before crossing over it, while in the second experiment, each robot constructed a slope leading up to a high step, allowing the robot to move onto the step. Both robots succeeded in completing these tasks successfully, with the main difference in performance being the time taken before the robot was able to traverse the obstacles. Using two-part polyurethane foam resulted in much shorter curing times, although the structures constructed were not as even as those for the one-part polyurethane foam, and the robot needed to wait 10 s between the applications of each successive layer of foam to account for the vertical expansion of the material. Our findings demonstrate the effectiveness of our polyurethane foam construction robots in overcoming obstacles in unknown rough terrain.

Autonomous dry stone

“…Generally combining mobile platforms with conventional industrial robots, these compound setups have been predominantly demonstrated with standardized building components (Dörfler et al 2016) or industrially produced chemical products (Keating et al 2014). Recent research has demonstrated the potential of robotic systems to construct auxiliary structures to achieve and maintain navigability in previously unknown or untraversable terrain, but these experiments have only been demonstrated at a small scale, and do not make use of naturally occurring found construction materials (like stones), but instead use compliant bags (Saboia et al 2019) or polyurethane foam (Fujisawa et al 2015) to homogenize the irregularities in their environment.…”

A Robust Polyurethane Depositing System for Overcoming Obstacles in Disaster Scenario Robotics

“…Compressive strengths of over 2M P a are possible, so that the solidified foam can easily support the weight of a human standing on it. Expansion ratios of over 30× the original volume are viable, meaning that 25dm 3 of solidified foam can be generated from just 0.84dm 3 of the two part liquid constituents [9]. These values depend largely on the mixing style and have been recorded through testing on the proposed system, as discussed in section III-B.…”

“…The foam in its final state is closed-cell, water-proof and lighter than water yet, as mentioned, still strong enough to support the weight of a human climbing thereon. Additionally, these foams adhere to a wide variety of materials including wood, iron, and concrete, among others [9]. Based on these characteristics, this material is suitable for use in disaster scenarios in real-time.…”

“…The second project related to the using of PU foam to overcome obstacles was proposed in [9]. This platform utilised an aerosol depositing system on a gimbal, with both single part and two part PU tested.…”

“…By driving the system with peristaltic pumps, the amount of liquid being driven at any point is equal to the volume inside the tubing and mixing devices, and is thus independent of the size of the reservoir from which it is being pumped. This implies that the flow generated by the pump is not affected by the size of the reservoirs, unlike in the syringe and aerosol driven designs used in [14] and [9], and therefore the system can potentially be significantly scaled without redesign. Furthermore, the system can control the flow rate of each pump independently so that the ratio between PU Part one and Part two can be easily controlled.…”