Design, Modeling and Indigenous Firmware of Patient Assistance Flexible Robotic System-Type I: Beta Version

The ensemble of Assistive Robotics is slowly emerging as the new front-edge research arena due to its wide-spread applications in health care sector. Although exoskeletons are is use to a limited extent in the field of health care, it has its own limitations so far the design, prototyping & miniaturization are concerned. Patient-centric customized health care is the need of the hour and research frontiers are also getting negotiated accordingly. One such promising application manifold of Assistive Robotics is the incorporation of multi-degrees-of-freedom flexible robotic system, equipped with tailor-made mini-gripper(s). In-line with the proposition an indigenous design, modeling and firmware of Patient Assistance Robot (PAR): Type I has been accomplished by us as version 1.0 prototype (Beta version). The characteristics of PAR v1.0 are identical to that of Flexible Robotic System with multiple links & intercepting joints, besides fittment of three different miniaturized grippers. The ensemble programming logic for the robot is developed towards controlling in-built vibration in real-time.


Introduction
The field of Flexible Robotic Systems (FRS) is one of the niche ensembles of present-day robotics research that caters for real-time aspects like rheology (stress-strain paradigms), in-situ vibration,   [21,22]. The proposition of real-time vibration signture of planr FRS & its harnessing has been discussed thoroughly by the author [23]. The paper has been organized in six sections. An overview It is important to note also the numerical measure of the crosssectional area of the i th. FRS-link, D i , based on its type, viz. radius 'r', length 'l' & breadth 'b' tuple and side's', respectively for circular, rectangular & square cross-sections. It is to be noted that the most significant aspect of FRS-design pertains to the choice of drive mechanism. In the present hardware we have adopted direct-drive approach, wherein miniature servomotors were placed at the joint itself. This design is comparatively robust from the point of view of actuation of the entire system but it suffers from poor vibration control. As the system tare weight is increased due to addition of servomotors at the link-joint interface, the trembling or in-situ vibration becomes more prominent in case of direct-drive FRS. On the basis of end-application requirement, we have used direct-drive system for the FRS-hardware in this work. Figure

Major paradigms of the prototype (Beta Version)
The working prototype of the PAR-typeI-v1.0 was fabricared indigenously, equipped with three nos. revolute joint-actuated links of unequal length but uniform cross-section and one no.

Description of the system controller of PAR
The backbone of the control system algorithm of the fabricated PAR-typeI-v1.0 is Proportional-Integral-Derivative (PID) control, augmented by a novel vibration (frequency) attenuation module. The overall control system facet has been tuned with currentbased cut-offs and electronic limit switches to arrest joint overrun.
The servo-based control of the PAR-joints as well as PAR-gripper has been effected with individual user-selective feedback gain amplifier(s). It is to be noted that the control system architecture of the prototype is composed of four distinct but similar PID loops, each one of that is responsible for the three joints of the PAR and

Experimentation with the prototype PAR and results
The prototype PAR-typeI-v1.0 was critically examined for its performance in real-time through different sets of trials & testings.
where, m i : mass of the i th. PAR-link; It is intertesting to note that equation 2 can be recast in a way so as to fit the real-time data, pertainig to run-time torque of the joint servomotor of PAR. For example, if PAR-typeI-v1.0 is excited by the j th. joint-servomotor, then the working formula for 'f n ' will be as follows: where, t motor In our case-study, we will register experimental data with respect to the activation of the first joint-servomotor of the PAR-typeI-v1.0 and we will investuigarte the efrect of such excitation on the third link of the PAR Table 2 Table   2. The paradigm of control dynamics of PAR in real-time essentially involves investigation of strain vis-à-vis vibration tuple. In case of 'direct-to-joint-drive' serial-chain FRS, the instantaneous real-time displacement, in the form of 'deflection', will be prudent in the links.
Nonetheless, the dynamic control of PAR-typeI-v1.0 is essentially data-driven and postulation-based, as generated from the damping model.

Conclusion
The indigenous hardware of a prototype serial-chain three-link Robotics, with many more challenges in task-handling by custommade miniaturized grippers.

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