## 3 Designing Robotic Caregiver Embodiments
### Evolution of Robotic Caregiver Embodiment
#### 3.1.1 Minimally Articulated Embodiment: Pole and PILLAR  
This robot embodiment challenged the notion of what is a robot vs. a tool. _Pole_ is lightweight, has minimal form factor, and is least like a human or humanoid robot. Pole provides minimum assistance and assumes that the OA has strength enough to use grab bars. Across all versions, the robot anticipates where the OA will need it next and goes to that location, locks in, provides support, and disengages. The robot's telescoping pole raises and then securely locks into the ceiling at designated areas in an OA's house. Also  
Figure 2: Our 4 original robot embodiments, aesthetic categories [8], and description.  
across all versions, the front pad can provide support when standing up and halt falling forward because the OA's chest would contact the robot's soft pad.  
Pole began as a vertical grab pole that can move around your house and be attached securely and stably (Figure 3, left), and an OA would grasp the vertical pole and pull themselves up or lower themselves down. The center pad was meant to be a soft area that an OA could learn their chest against when going from a sitting position to standing. However, the placement of the center pad, cameras, telescoping pole, and wheels was awkward for an OA to use beyond sit-to-stand maneuvers.  
We evolved the Pole concept into _PILLAR_ (Figure 3, middle) which provided horizontal grab bars as well; these low degree of freedom \"arms\" are also soft as denoted in orange. We drew inspiration from rollator walkers and changed the wheel design to accommodate where an OA would step. When the telescoping pole retracts, the OA has a clear line of sight ahead, thus, PILLAR could also be used as a walker if needed.  
PILLAR had limited functionality, and when compared to the other robot embodiments discussed below, we realized that a robot with fewer features than the others would not be viewed as valuable to prospective OAs to bring into their home. From our previous OA User Needs Finding research [13], we brought forward OAs' desires to maintain their physical fitness and desire for social interaction. We included a retractable screen and a sensor bar which could be used for a remote instructor to guide an OA through an exercise routine; the horizontal bars could provide stabilization for the OA while exercising. The base had several evolutions beyond Figure 3. We explored how it dynamically changed its outriggers to widen its footprint, including instances in which it only used 1 outrigger to not block the OA standing up and walking (depicted in Figure 6, Scenario 1, Frame 3).  
**Final Design of PILLAR.** Shown in Figure 4b, the final design of PILLAR is a simplistic design and can only provide min assistance; PILLAR is not able to increase support or change support in terms of direction or angling. In this final design, the retractable screen was made at eye level appropriate height for exercise. The body frame was slimmed back down to 1 vertical pole to reduce the visual footprint and kept 2 horizontal arms. Because we went back to 1 pole, we included an additional wheel locking mechanism to increase stability and security. This final variation still could slide vertically up/down to flex with an OA's movements (i.e., sit-to-stand) or make a \"T\" pose to create a long horizontal grab bar when needed (e.g., stepping over a threshold). PILLAR's appearance is categorized as functional, and because PILLAR has no discernible face, it is unlikely that OAs would treat it socially.  
Figure 3: Concept evolution of POLE (**left**) into PILLAR (**middle**), PILLAR evolution (**right**). Shown here, the robot’s telescoping vertical pole locks into the ceiling when in use, and retracts to minimize its visual footprint.