Mobile Carrying Platform: I-Explore

This paper presents the development of mobile transportation robot, i-Explore. Since 2018, ART (Assistive Robot Team) in University of Hartford has designed and built i-Explore platform. The main objective of i-Explore is to assist and carry children who have severe physical disabilities in indoor environments, especially for domestic uses.  

Various factors generate limitations on a person’s mobility and such physical disabilities include, but not limited to, cerebral palsy, spinal cord injury, muscular dystrophy and etc. Down syndrome (DS) is also one of the most important causes of physical disabilities by delaying children to develop motor functions (associated with other impairments such as muscle hypotonia and joint hyper-extensibility). The children who could not achieve enough development of their limb control, they often swipe arms largely over all directions and sometime hit objects or people in the way. It is not intentional and is just their body response to commands for the intended movement. Similar cases also happen in their legs. As such, they cannot control their limbs accurately as they originally planned. The net result is that such children cannot walk or use electric wheelchairs by themselves, so cannot navigate even their home.

To assist such children who need special needs, a mobile transportation robot platform is under development by ART and two different prototypes are introduced in this study. In previous studies, ART developed the small caterpillar-type service robot, SCSR, for navigation in rough terrains. Fast reactiveness to surrounding environments and low-cost manufacturing were main technical design requirements. They are continuously adopted to design and build i-Explore in this study.   

In this paper, the mechanical design of i-Explore is described initially. The prototype which is developed based on the passive wheelchair structure is introduced first. Then, various technical issues which were encountered from the design are addressed. Based on the lesson from the first design, the second prototype is built based on the mini size go-kart and its mechanical and electrical features are demonstrated in this paper. As such, commercially available platforms, a wheelchair and a go-kart, are used for base structures for the first and the second prototypes of i-Explore platform respectively in this study. It resulted in low cost manufacturing and easy maintenance of the developed platform. 

Next, based on the mechanical specification of the built platform, kinematic analysis of i-Explore is also implemented. The differential drive motions which enable i-Explore to navigate in the given indoor space are designed based on the kinematic equations which is derived above. Then, the designed motions are executed thorough the actuator of each side in synchronous way using the unified real-time controller. The low-level controller was also connected with various sensors which provides obstacle detection capability of the built platform and the communication module which allows the robot to be controlled remotely by parents.

Last, the built robot is tested and evaluated in various environments which include both indoor and outdoor spaces. Through the experimentation, i-Explore demonstrated its fast reactiveness to obstacles and strong power to transport children in domestic environment safely and autonomously.