Not just how good — what's good, what's off, and what to fix next.
Record one overhead swing. Pose Coach scores it across four dimensions, grades it S–D, and points to the one thing to work on next. This page explains how the score is calculated, how to read it, and how to use it.
One score. Four things behind it.
For each overhead stroke, Pose Coach reads four dimensions from your 3D skeleton, scores each 0–100, then weights them into one 0–100 overall score and an S/A/B/C/D grade. Speed is just one piece — completeness, angles and consistency matter just as much.
A weighted blend of four dimensions. The grade is the overall score mapped to a letter — the same S–D scale that powers our running score, so grades are comparable across sports: your badminton B and your running B are one ruler.
Default weights: Completeness 30% · Tempo 25% · Joint Angles 25% · Stability 20%. A coach view auto-shifts to 35 / 20 / 30 / 15, weighting technical accuracy more.
| Grade | Label | Overall score |
|---|---|---|
| S | Outstanding | ≥ 90 |
| A | Excellent | ≥ 80 |
| B | Good | ≥ 70 |
| C | Pass | ≥ 60 |
| D | Needs Work | < 60 |
The four dimensions
Each dimension answers three questions: what it measures, what a top score looks like, and how to improve it. The order never changes — it matches the app's score card.
Completeness
Measures — A full overhead stroke has three phases: backswing → contact → follow-through. This checks whether each swing completes all three — backswing up above the shoulder, deep enough (not a shallow flick), an actual contact, and a follow-through that extends.
Top score — all three phases on every swing, backswing above the shoulder with depth. In-app: backswing 3/3 (2 deep), contact 3/3, follow-through 3/3.
- Backswing above the shoulder
- Full three-phase swings
- Don't cut the follow-through
Tempo
Measures — two things: how fast you swing (peak speed at contact) and how well you load (backswing as a share of the whole stroke). The sweet spot is a 40–60% backswing share — too fast and you don't load, too slow and you miss the release.
Top score — peak speed near the high-level range, backswing share inside 40–60%. In-app: avg peak 12.5 m/s; backswing share 48% (target 40–60%).
- Burst power at contact
- Slow the backswing to load, then accelerate
- Keep tempo steady
Speed is 60% of this dimension, rhythm 40%. A calibrated reference appears once enough same-stroke samples exist.
Joint Angles
Measures — how far your key-frame joint angles (shoulder / elbow / wrist / hip, across the three phases) deviate from a reference — the average degrees off. Smaller deviation, higher score.
Top score — average deviation near 0°. Reference scale: within 5° ≈ full marks, 15° ≈ 87, 30° ≈ 67, 50° ≈ 40, 80° → zero. In-app: avg deviation 18.5°, largest in the swing phase.
- Bend the elbow ~30° more before the swing
- Lock the wrist firm at contact
- Open the shoulder fully
Joint angles need a clear side view — facing the camera head-on can make this metric unavailable. Switch camera angle to get it.
Stability
Measures — how consistent you are swing-to-swing: body/device steadiness plus rhythm regularity across swings. Steadier and more regular scores higher.
Top score — stand steady, brace the core, racket arm doesn't wobble, every swing close in rhythm.
- Plant your feet, center your weight
- Brace the core to cut sway
- Keep the racket arm steady
Stability compares across swings, so record 3+ swings for a reliable read.
Your score card, element by element
Open the score card and every element is telling you one thing.
- Score ring + grade badge — the overall 0–100 and its S/A/B/C/D letter. A Personal Best badge appears when you set a new high.
- One-line summary — names your strongest and weakest dimension in plain language (its tone adapts to your role — see below).
- Four dimension bars — Completeness / Tempo / Joint Angles / Stability, each with its score and a one-line detail.
- Next Focus — points at your weakest dimension, e.g. "Focus on joint angles next."
- Tips to Improve — always three, ranked by leverage.
- Per-Swing Breakdown — each swing's score and weakest point; tap to replay that swing or save it as a reference.
- Engine version + notice — the scoring engine version and an honest reminder that scores are directional guidance.
Confidence: 3 or more swings counts as high confidence. Fewer shows "Low sample size — result is approximate." Record a few more swings and the score gets more trustworthy.
Not "keep practicing" — the exact three things to work on
Every score comes with three tips, ranked by leverage — the lowest-scoring dimension first. Each is concrete and quantified, not a platitude.
| 1 | Bend the elbow 30° more before the swing |
| 2 | Lock the wrist firm at contact |
| 3 | Plant your feet, center your weight |
Next Focus names the single dimension to drill. Tap Generate Training Plan to feed the score to the AI coach and get a targeted plan. When all four dimensions are already high (each ≥ 85), the tips switch to maintain / challenge mode.
Mixed a smash, a drop and a clear into one recording? The score is based on the most frequent stroke type, and the app suggests recording one type on its own for sharper, more targeted scoring.
Same swing — a different read for player, parent, coach
The numbers are identical for everyone; only the summary's tone changes. A coach view also shifts the weights toward technical accuracy (Joint Angles 25→30%, Completeness 30→35%) and eases off the noisier-when-sparse Stability (20→15%).
Player
Encouragement — "Scored A (82). Tempo is your strength — watch your joint angles!"
Parent
Reassurance — "Your child scored A (82). Tempo stands out; joint angles still has room to grow."
Coach
A prescription — "Overall A (82). Recommend focused joint-angles training."
What this score can — and can't — do
Scores reflect AI motion analysis and are directional guidance — not a clinical or professional assessment.
It can
- Quantify four dimensions of your overhead strokes (clear / smash / drop)
- Point to the one thing to work on, with actionable tips
- Track consistency across multiple swings
- Read joint angles from a clear side-view recording
Keep in mind
- v1.0 focuses on overhead strokes — net shots and drives aren't scored yet
- It doesn't replace a real coach's on-court judgment
- Fewer than 3 swings is flagged "result is approximate"
- A head-on camera may disable the joint-angle metric
If no complete swing is detected, or a clip can't be scored (low frame rate / screen recording), the app asks you to re-record in-app. When arm tracking degrades, the angle and completeness metrics are flagged as lower confidence rather than shown as exact.
Your next swing deserves a score.
Record one overhead swing and see your four dimensions, your grade, and the one thing to work on next.
Scoring engine v0.8.0 · Scores reflect AI motion analysis and are directional guidance, not a clinical or professional assessment.