Page 53 - ASME DSCC 2015 Program

Technical Program

a Soft-Sensing Technique for Measurement of Mass flow rate In a with less than 5% error. Also, a preliminary experiment with a human subject
Liquid-Liquid heat exchanger in standing position was performed, and the estimated quasi-static imped-
Contributed regular paper. DSCC2015-9881 ance of the ankle was estimated at 319 Nm/rad in DP and 119 Nm/rad in IE.
Sangeeta nundy, Siddhartha Mukhopadhyay, Alok Kanti Deb, Indian Assist-as-needed Controllers for Index finger Module of a Hand
Institute of Technology Kharagpur, Kharagpur, West Bengal, India Exoskeleton for Rehabilitation
This paper presents a soft-sensing technique of determining the mass flow Invited session paper. DSCC2015-9790
rate of a liquid-liquid heat exchanger using temperature measurements Priyanshu Agarwal, Benito fernandez, Ashish Deshpande, The University
and a distributed parameter model. The efficiency of a heat exchanger is of Texas at Austin, Austin, TX, United States
intimately related to its mass flow rate and as a consequence mass flow
We present two types of subject-specific assist-as-needed controllers for
rate measurements are essential for any fault detection or monitoring
the index finger module of a hand exoskeleton designed for rehabilitation
program of the heat exchanger. However the costly mass flow rate sensor
after a neuromuscular impairment such as stroke. Learned force-field control
measurements can be bypassed by this soft-sensing technique which
is a novel control technique in which a neural-network-based model of the
primarily employs measurements from inexpensive temperature sensors.
required torques given the joint angles for a specific subject is learned
We first develop a distributed parameter model of the counter flow type heat
and then used to build a force-field to assist the finger joint motion of the
exchanger using energy balance equations. Thereafter, a state-space model
subject to follow a trajectory designed in the joint-angle space. Adap-
of the heat exchanger is formulated using orthogonal collocation method
tive assist-as-needed control, on the other hand, estimates the coupled
where temperature at the collocation points and the unknown mass flow
finger-exoskeleton system torque requirement of a subject using radial
rate are considered as the state variables. The mass flow rate is estimated
basis function (RBF) and on-the-fly adapts the RBF magnitudes to provide a
by a Hybrid Extended Kalman Filter algorithm using the outlet temperature
feed-forward assistance for improved trajectory tracking. Experiments on the
measurements. The sensitivity of the soft-sensing technique in presence
index finger exoskeleton prototype with a healthy subject showed that while
of modeling errors and measurement noise is also studied using a suitable
the force-field control is non-adaptive and there is less control on the speed
simulation example.
of execution of the task, it is safer as it does not apply increased torques if
the finger motion is restricted. On the other hand, adaptive assist-as-needed
InVITED SESSIon
2-10-1 TM5 Rehab Robotics controller adapts to the changing needs of the coupled finger-exoskeleton
Emerson Burkhart A 1:30pm–3:30pm system and helps in performing the task with a consistent speed, however,
applies increased torques in case of restricted motion resulting in potential
Session Organizer: Kevin fite, Clarkson University user discomfort.
Session Organizer: Mo Rastgaar, Michigan Technological University Multi-objective optimization of Impedance Parameters in a Prosthesis
Session Organizer: frank Sup, University of Massachusetts, Amherst Test Robot
Session Organizer: Robert Gregg, University of Texas, Dallas Invited session paper. DSCC2015-9848
Session Chair: Mohammad Rastgaar Aagaah, Michigan Technological
Poya Khalaf, Hanz Richter, Antonie J. van den Bogert, Daniel J. Simon,
University
Cleveland State University, Cleveland, OH, United States
Session Co-Chair: Edmond Richer, Southern Methodist University
We design a control system for a prosthesis test robot that was previously
Instrumented Walkway for Estimation of the Ankle Impedance in developed for transfemoral prosthesis design and test. The robot’s control
dorsiflexion-plantarflexion and Inversion-eversion during Standing system aims to mimic human walking in the sagittal plane. It has been seen
and Walking in previous work that trajectory control alone fails to produce human-like
Invited session paper. DSCC2015-9774 forces. Therefore, we utilize an impedance controller to achieve reasonable
Evandro ficanha, Mohammad Rastgaar Aagaah, Guilherme Aramizo tracking of motion and force simultaneously. However, these objectives con-
Ribeiro, Michigan Technological University, Houghton, MI, United States flict. Impedance control design can therefore be viewed as a multi-objective
optimization problem. We use an evolutionary multi-objective strategy called
This paper describes in detail the fabrication of an instrumented walkway
Multi-Objective Invasive Weed Optimization (MOIWO) to design the imped-
for estimation of the ankle mechanical impedance in both dorsiflexion-plan-
ance controller. The multi-objective optimization problem admits a set of
tarflexion (DP) and in inversion-eversion (IE) directions during walking in
equally valid alternative solutions known as the Pareto optimal set. We use
arbitrary directions and standing. The platform consists of two linear actua-
a pseudo weight vector approach to select a single solution from the Pareto
tors, each capable of generating ±351.3 N peak force that are mechanically
optimal set. Simulation results show that a solution that is selected for pure
coupled to a force plate using Bowden cables. The applied forces cause the
motion tracking performs very accurate motion tracking (RMS error of 0.06
force plate to rotate in two degrees of freedom (DOF) and transfer torques
cm) but fails to produce the desired forces (RMS error of 70% peak load). On
to the human ankle to generate DP and IE rotations. The relative rotational
the other hand, a solution that is selected for pure force tracking successful-
motion of the foot with respect to the shin is recorded using a motion cap-
ly tracks the desired force (RMS error of 12.7% peak load) at the expense of
ture camera system while the forces applied to the foot are measured with
motion trajectory errors (RMS error of 4.5 cm).
the force plate, from which the torques applied to the ankle are calculated.
The analytical methods required for the estimation of the ankle torques,
rotations, and impedances are presented. To validate the system, a mockup
with known stiffness was used, and it was shown that the developed system 53
was capable of properly estimating the stiffness of the mockup in two DOF