How it works
Measured, not inferred.
Every MoCaddieIQ™ sensor is the same small motion unit: an accelerometer and a gyroscope, a Bluetooth radio, a rechargeable cell, 28 grams. Its position on you is a setting. The app puts them together into one picture of the swing — and is honest about which parts of that picture are measured and which are estimated.
Why a sensor on the club, and two on the wrist
The club sensor
Wrist-only devices infer where the club is from wrist angles, so every "shaft parallel" or "top of swing" they report is a deduction. A sensor in the butt of the grip removes the inference — and it is how we measure tempo, plane, and whether the club came down steeper than it went back, from a single sensor, with no body reference needed.
Hand and forearm
A wrist angle is the difference between two bodies. A hand sensor alone cannot separate wrist hinge from forearm rotation, because both move the hand. So MoCaddieIQ Wrist is three sensors, not two: club, hand, forearm.
Back and pelvis
The kinematic sequence — pelvis, then chest, then arm, then club — is the order and timing of peak rotation speed. A gyroscope measures rotation speed directly; a camera has to see a silhouette turn about its own axis, which it barely can. That is why Full Swing adds the lumbar and upper-back sensors.
Calibrated at address
Every session re-zeroes at your address position, so a strap that sits a centimetre off from last time does not matter. What matters is that a sensor stays put during the swing — which is what the harness and mounts are designed for.
What we measure — and with which kit
| Group | Metrics | Source | Kit |
|---|---|---|---|
| Transition — over-the-top | The plane the club comes down on against the plane it went back on. Steeper = over the top; flatter = shallowed. The Pump drill grades the fix rep by rep. | IMU-DIRECT | Wrist |
| Tempo | Backswing and downswing time, the ratio (about 3:1 on Tour), timed from the club | IMU-DIRECT | Wrist |
| Swing plane | Plane tilt and on-plane consistency, measured off the club itself | IMU-DIRECT | Wrist |
| Swing length & takeaway | Clock-face ladder 7:00–10:00, graded to ±1.5° and coached by voice through earbuds | IMU-DIRECT | Wrist |
| Wrist & release | Lead-wrist flexion/extension and deviation (hand minus forearm); cast and release timing | IMU-DIRECT | Wrist |
| Club delivery | Face angle, club path, attack angle, shaft lean at impact | ESTIMATE | Wrist |
| Kinematic sequence | Firing order and timing: pelvis → thorax → arm → club; flags "out of order" | IMU-DIRECT | Full Swing |
| Body rotation & posture | Shoulder turn, hip turn, X-factor and X-factor stretch, early extension, side bend, sway | IMU-DIRECT | Full Swing |
| Weight shift & balance | Lead/trail distribution, centre-of-pressure path, pressure-shift timing | IMU-DIRECT | Ground Up |
| Video review | Per-repetition clips with the target line drawn on, jumping straight to the frame the club reached the top | CAMERA | Wrist |
IMU-DIRECT: measured straight from the sensors. ESTIMATE: inferred, and labelled as such in the app. CAMERA: needs the phone camera.
The faults we detect today
These are the faults the app fires on from real sensor data now — not the whole coaching catalogue, which is larger, and grows as detectors are built and tested. Each says which kit sees it.
Over-the-top
The club comes down steeper than it went back, thrown outside the line at the start of the downswing. The grip sensor measures the plane change on every swing; the body pair (Full Swing) shows whether the shoulders, not the hips, started the downswing. The Pump drill grades the fix rep by rep.
Open face · slice
Clubface pointing right of the target at impact — the slice for a right-hander. From the grip sensor, and labelled an estimate: rotation about the shaft is the hard one for any consumer device.
Casting · early release
The wrists let go too early in the downswing, dumping the angle before the hands reach hip height. Timed from the hand sensor against the club.
Sway
The hips slide away from the target in the backswing instead of turning. From the lumbar sensor.
Reverse spine tilt
The upper body leans toward the target at the top — the fault most linked to lower-back pain. From the upper-back sensor.
Fast tempo
Backswing-to-downswing ratio well under the 3:1 most good players show. Timed from the club.
Scooping
Shaft leaning backwards at impact with an iron — the hands trying to lift the ball. Shaft lean from the grip sensor, estimate-grade.
Weak turn · X-factor
Too little separation between shoulder turn and hip turn at the top — the coil that stores power. From the lumbar and upper-back pair.
Steep driver attack
Hitting down on the driver instead of up. Attack angle from the grip sensor, estimate-grade.
…and more, as each detector is proven
The coaching catalogue behind the app describes forty-odd faults — early extension, chicken wing, loss of posture, reverse pivot, flying elbow among them. They go on this list only when a detector fires on real swings, not before.
Feel the fault where it happens
Today the feedback comes from the phone: spoken, plus a buzz in Drill Mode. The production sensors will add a small vibration motor to every sensor worn on the body and to the belt hub — and to the club sensor if it fits. The buzz will come on the part that went wrong: the wrist when the wrist is out of position, the lower back when the hips sway, the bicep when the lead arm leaves the chest. In putting, if the club sensor carries one, you will feel it through the grip in both hands. The hub will also give silent alerts — ready, a sensor out of range, swing saved. Strength will be adjustable, with a silent mode.
More coming with the production sensors
- The buzz during the swing. A faster, wider-range motion sensor keeps even the fastest swings inside what it can measure, and lets each sensor recognise the top of the swing and impact itself — so the buzz will come during the swing, not only when you hold a position.
- A glance at your wrist. A green or red flash on the wrist sensor after each swing, bright enough to read in sunlight, so you will not need to look at your phone.
- A built-in compass. True aim and target line, turn figures that will not drift over a long session, and shot direction on the course.
- Hears the strike. The hub and club sensor will hear the ball being struck, to tell a real shot from a practice swing and time impact exactly. They listen for the strike only — they will never record sound or speech.
- Uphill and downhill. An altitude sensor in the hub for "plays like" distances on the course, and a small beeper to find the hub in your bag.
- Easier to live with. Tap your phone on a sensor to pair it; "Find my sensor" makes it blink and buzz from the app; and a steadier, more accurate battery percentage.
A word before you start
Golf is not an easy game to master, and no sensor changes that. MoCaddieIQ will tell you exactly what your swing did and hand you a fix that matches it — but the fix only works if you work on it. Every drill is there to give you the feel of the right path and, through repetition, the muscle memory to keep it when it counts. Put the reps in, on the range and at home, and the numbers will show you the change — and what the numbers show, the golf course will confirm. Skip them and the fault stays. It won't fix what you don't work on.
Honest limits — we name them
Clubface angle at impact is an estimate
Rotation about the shaft axis is the noisy one for a grip sensor. We estimate it and say so. It is the hardest consumer metric, even for premium systems.
Lead-wrist angle is being validated
The method is documented and the sensor positions exist; the implementation is the defined objective of the feasibility study, benchmarked against a borrowed wrist-only device on the same swings. Until it ships it is a design claim, not a demonstration.
Weight shift needs the insoles
Weight shift is never inferred from the motion sensors. It comes from the Ground Up pressure insoles or not at all.
We do not measure ball flight
Spin, launch and carry are a radar's job. MoCaddieIQ measures the swing; your launch monitor measures the ball. They are better together.