wpilibsuite/allwpilib

Implement Tsitouras 5th order numerical integrator

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#7,123 opened on Sep 23, 2024

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component: wpimatheffort: 2good first issuetype: feature

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Description

This issue is a spin-off of https://github.com/wpilibsuite/allwpilib/issues/4373.

The Tsitouras 5th order integration method is 3x more accurate than Dormand-Prince (RKDP). It uses the exact same algorithm with different coefficients.

Section 7.9 of Controls Engineering in FRC has an introduction to the notation of Runge-Kutta methods.

Here's the paper to implement: http://users.uoa.gr/~tsitourasc/RK54_new_v2.pdf

Here's the implementation steps:

  1. Copy-paste the RKDP function(s) to make a new function Tsit5
  2. Update the coefficients of A, b1, and b2 to reflect those in section 3, table 1 of the paper above (A maps to a, b1 maps to b, and b2 maps to b̂)
  3. Update the source location comment in the function
  4. Copy-paste and modify the tests
  5. Replace usages of RKDP with Tsit5

Contributor guide

Research direction
Locate the existing RKDP integration functions in the WPILib codebase (likely in trajectory classes). Copy the function, rename it to Tsit5, and replace the coefficients (A, b1, b2) with the values from Table 1 of the referenced paper. Update source location comments, copy and modify the corresponding tests, then replace all usages of RKDP with Tsit5.
Tech stack
cppjava
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitC++ or Javabasic understanding of Runge Kutta methods
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70