$\newcommand{\deriv}[2][]{\dfrac{\partial #1}{\partial #2}} \newcommand{\tderiv}[2][]{\tfrac{\partial #1}{\partial #2}} \newcommand{\fderiv}[2][]{\dfrac{d #1}{d #2}} \newcommand{\derivII}[3][]{\dfrac{\partial^2 #1}{\partial #2 \partial #3}} \newcommand{\tderivII}[3][]{\tfrac{\partial^2 #1}{\partial #2 \partial #3}} \newcommand{\derivIII}[4][]{\dfrac{\partial^3 #1}{\partial #2 \partial #3 \partial #4}} \newcommand{\tderivIII}[4][]{\tfrac{\partial^3 #1}{\partial #2 \partial #3 \partial #4}} \newcommand{\derivIV}[5][]{\dfrac{\partial^4 #1}{\partial #2 \partial #3 \partial #4 \partial #5}} \newcommand{\half}{\tfrac{1}{2}} % Macro for 1/2 \newcommand{\ud}{\mathrm{d}} \newcommand{\op}{\circ} \newcommand{\dq}{\dot{q}} \newcommand{\ddq}{\ddot{q}} \newcommand{\dt}{\Delta t}$

NonlinearConfigSpring – Nonlinear spring acting on a configuration variable

Like ConfigSpring which creates a spring force directly on a generalized coordinate, a NonlinearConfigSpring implements a force, \(F_{q}\) on a generalized coordinate which can be a function of configuration:

\[F_{q} = -f (m\cdot q+b)\]

where \(f\) is a spline function provided by the user, \(m\) is a linear scaling factor, and \(b\) is an offset value.

Implemented Calculations

Calculation	Implemented
V	N
V_dq	Y
V_dqdq	Y
V_dqdqdq	Y

NonlinearConfigSpring Objects

class trep.potentials.NonlinearConfigSpring(system, config, spline[, m=1.0, b=0.0, name=None])

Create a new nonlinear spring acting on the specified configuration variable. The configuration variable must already exist in the system.

NonlinearConfigSpring.config

The configuration variable that spring depends and acts on.

(read only)

NonlinearConfigSpring.spline

A Spline object relating the configuration to force. See the trep.Spline documentation to create a spline object.

NonlinearConfigSpring.m

A linear scaling factor on the configuration.

NonlinearConfigSpring.b

An offset factor on the scaled configuration.