Embedded Force Sensor for Pronation/Supination

Supervisor: Carlo Menon

Background: Biomedical wearable devices commonly rely on signals sensed using a variety of transducers in order to adapt or respond appropriately to a user. Transducers used typically convert mechanical (position, velocity, pressure etc.) to electrical energy. Depending on the biomedical device and type of application, different transducers may be chosen as most appropriate. For example an arm exoskeleton collecting information about the range of motion would likely require kinematic information, and a device relying on muscle activity information to interpret user intent would use Electromyography (EMG) sensors. With our exoskeletons, it is often useful for us to observe user-device interaction forces. We have already developed exoskeleton embedded force sensors for elbow flexion/extension. We are now aiming to develop an embedded pronation supination force sensor (EPSFS). The objective is to embed the transducer in the exoskeleton structure; this reduces bulkiness, and increases measurement accuracy by collecting the signal in proximity to the source and hence more directly.

Research to be performed: The student participating in the proposed co-op will be involved on the development of the EPSFS prototype. The EPSFS will be designed using analytical calculations, CAD and simulation software (such as SolidWorks and ANSYS). The main design aspect will consist of the structural design, which will have a direct impact on the signal sensitivity and quality. A strain gauge transducer can be installed directly on the structure. Alternatively a strain gauge that is pre-installed on a beam (load cell) can be purchased and embedded in the structure. Other design and implementation techniques will also be considered. The last phase of the work will consist of implementing and characterizing the EPSFS in one of the lab exoskeletons.

Depending on the student’s skills and state of the project at the beginning of the co-op period, the work/research will focus on the development of some of the following subsystems of the EPSFS: (1) mechanical design, (2) electronics, (3) implementation, (4) characterization.

Prerequisite:  1) at least 100 credit hours; and 2) CGPA>2.8.

Notes: 1) Minimum honorarium is provided; 2) The ideal candidate would like to contribute in applied research and be willing to work on a mechatronic project. However, students with expertise in at least one of the above mentioned six subsystems are invited to apply.

Significance: The human arm and hand are the most used parts of our musculoskeletal system. Pronation and Supination is an essential sub-movement of the upper limb in activities of daily living. It is thus essential to incorporate this degree of freedom in biomedical wearable designs. While it is relatively simple with current technology to implement kinematic transducers such as angular position and rate for pronation/supination, obtaining a reliable force measurement using a compact system remains an elusive alternative. The development of the EPSFS will represent a crucial tool for any further investigation relying on arm force sensing. We plan to develop an independent module suitable to be embedded in a variety of wearable arm devices.