calcRamp¶

Calculates a k-space trajectory connecting two given points (k0 and kend) while adhering to gradient and slew rate limits. The function iteratively tries to find a solution with an increasing number of intermediate points until it finds a trajectory satisfying the constraints, or until a maximum number of points is reached. The resulting trajectory is not guaranteed to be the absolute shortest, but it's a reasonably short connection.

Syntax¶

function [kout, success] = calcRamp(k0,kend,varargin)

Calling Pattern¶

mr.calcRamp(...)
mr.calcRamp('ParameterName', value, ...)

Parameters¶

This function accepts both positional parameters and name-value pairs.

Required Parameters¶

Parameter Name	Value Type	Description	Example	Units
`k0`	double	Two preceding points in k-space. Size is [3,2], representing the x, y, and z components of the two points.	`[ [0;0;0], [1;1;1] ]`	1/m
`kend`	double	Two following points in k-space. Size is [3,2], representing the x, y, and z components of the two points.	`[ [2;2;2], [3;3;3] ]`	1/m

Name-Value Pair Arguments¶

Parameter Name (string)	Value Type	Default	Description	Example
`system`	struct	`[]`	A structure containing system parameters. If empty, default system parameters are used. Should contain fields like maxGrad and maxSlew.	`mr.opts()`
`'MaxPoints'`	double	`500`	Maximum number of k-space points allowed in the connecting trajectory. Limits the computation time. Valid values: >0	`1000`
`'maxGrad'`	double	`0`	Maximum gradient strength. Can be a scalar (total vector gradient) or a 3x1 vector (per-coordinate limits). If 0, the value from the 'system' parameter is used. (Units: Hz/m)	`40e6`
`'maxSlew'`	double	`0`	Maximum slew rate. Can be a scalar (total vector slew rate) or a 3x1 vector (per-coordinate limits). If 0, the value from the 'system' parameter is used. (Units: Hz/(m*s))	`200e6`
`'gradOversampling'`	logical	`false`	If true, the gradient raster time is halved. Affects the gradient discretization.	`true`

Returns¶

Output	Value Type	Description
`kout`	double	Connecting k-space points (excluding k0 and kend). Size is [3, Nt], where Nt is the number of steps between k0 and kend. Units are 1/m.
`success`	logical	A flag indicating whether a solution was found (1) or not (0).

Examples¶

[kout, success] = mr.calcRamp([ [0;0;0], [1;1;1] ], [ [2;2;2], [3;3;3] ], 'maxGrad', 40e6, 'maxSlew', 200e6)