Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Impedance Control of a Transfemoral Prosthesis using Continuously
  Varying Ankle Impedances and Multiple Equilibria   Impedance controllers are popularly used in the field of lower limb
prostheses and exoskeleton development. Such controllers assume the joint to be
a spring-damper system described by a discrete set of equilibria and impedance
parameters. Said parameters are estimated via a least squares optimization that
minimizes the difference between the controller's output torque and human joint
torque. Other researchers have used perturbation studies to determine empirical
values for ankle impedance. The resulting values vary greatly from the prior
least squares estimates. While perturbation studies are more credible, they
require immense investment. This paper extended the least squares approach to
reproduce the results of perturbation studies. The resulting impedance
parameters were successfully tested on a powered transfemoral prosthesis, AMPRO
II. Further, the paper investigated the effect of multiple equilibria on the
least square estimation and the performance of the impedance controller.
Finally, the paper uses the proposed least squares optimization method to
estimate knee impedance.

26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc