Software for tracking strength training
601 USD TECHNICAL TASK
Project: Strength Exercise Tracking System
Version: MVP 1.0
⸻
1. Purpose
To implement stable software interaction between:
• Athlete's wristband (Wrist Unit)
• Up to 10 motion sensors (Weight Sensors)
• Mobile application (iOS / Android)
The system must:
• Identify the active sensor
• Synchronize the movement of the wristband and the sensor
• Transmit data to the application
• Calculate basic exercise metrics
⸻
2. System Architecture
2.1 Components
1️⃣ Wrist Unit (wristband)
• IMU (accelerometer + gyroscope)
• BLE module
• Unique ID
• Sampling frequency: 50–100 Hz
2️⃣ Weight Sensor (sensor on dumbbell/barbell)
• IMU
• BLE
• Unique ID
• Magnetic or mechanical attachment
• Sampling frequency: 50–100 Hz
3️⃣ Mobile application
• BLE Central
• Data processing
• Visualization
• Workout logging
⸻
3. Interaction Protocol
3.1 Type of Communication
Bluetooth Low Energy (BLE 5.0)
3.2 Roles
• Wristband — Peripheral
• Sensors — Peripheral
• Smartphone — Central
⸻
4. Operation Logic
4.1 Starting the Workout
1. The user opens the application
2. The application scans for available BLE devices
3. Displays the list:
• Wrist Unit (1)
• Weight Sensors (up to 10)
4. The user connects:
• Their wristband
• Selected sensors
⸻
4.2 Identifying the Active Sensor
Algorithm:
1. The wristband registers arm movement
2. The sensor registers weight movement
3. The application:
• Compares timestamps
• Correlates IMU signals
4. If correlation > specified threshold → sensor is active
6.1 MVP Metrics
The programmer must implement:
• Repetition detection
• Repetition tempo
• Time under tension (TUT)
• Movement amplitude
• Pause between sets
⸻
6.2 Repetition Detection
Repetition =
1. Upward movement (positive phase)
2. Peak
3. Downward movement (negative phase)
4. Reaching the baseline position
Method:
• Peak analysis along the main movement axis
• Noise filtering (low-pass filter)
• Threshold amplitude
⸻
7. Synchronization
Mandatory:
• All devices must synchronize time via smartphone
• Drift compensation every 30 seconds
• Maximum error ≤ 10 ms
⸻
8. Connection Stability
The programmer must:
• Implement auto-reconnect
• Handle packet loss
• Log % packet loss
• Buffering on the device (2–5 seconds)
⸻
9. Calibration
At first launch:
1. The user stands still
2. The gravitational axis is determined
3. A zero point is established
⸻
10. Security
• Encryption of BLE connection
• Authorization via session token
• Binding sensors to account
⸻
11. Non-functional Requirements
• Transmission delay ≤ 100 ms
• Connection to 10 sensors simultaneously
• Operation for 90+ minutes without interruption
• Battery consumption optimized
⸻
12. What the Programmer Needs to Implement
Firmware:
• BLE service
• Packet formation
• Timestamp
• Buffering
• OTA update support
Mobile:
• BLE scanning
• Device management
• Stream synchronization
• Correlation algorithm
• Repetition detection
• Workout logging
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14 days601 USD
7123 53 0 14 days601 USD
I am interested in your project for software for tracking strength training, especially the task of stable interaction between the bracelet, sensors, and mobile application. My 5 years of experience in developing mobile applications on Flutter for iOS/Android, as well as building efficient backends on Python/TypeScript, is perfectly suited for such a system. I am ready to apply my skills for effective integration of sensors and creating an intuitive user interface. I would be happy to discuss the details and propose optimal solutions for implementing your MVP.
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14 days590 USD
238 14 days590 USD
Good day! I specialize in the development of Desktop and Mobile applications. Very ambitious project. Ready to discuss the details of the development.
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30 days601 USD
1958 25 0 30 days601 USD
Good evening. I am developing firmware for the Nordic nRF52, nRF53, nRF54 series MCUs. I am well acquainted with the nRF52840 microcontroller. I can write BLE firmware for this microcontroller based on the nRF Connect SDK / Zephyr RTOS.
- Peripheral or Central role.
- Implement standard or custom BLE service.
- Polling, sending data from sensors.
- Firmware update (FOTA).
- Create Zephyr configuration for your board with hardware description.
The cost and deadlines are written conditionally. I would like to learn more about the project in detail. What sensors will be used, the data transmission format, and overall how urgent the project is.
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30 days601 USD
7 1 30 days601 USD
Good day.
I have experience and a desire to work.
I will complete it within the agreed deadlines.
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27 days601 USD
2662 53 0 1 27 days601 USD
Good day! I have extensive experience in developing various mobile applications, including those with BLE.
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3 days601 USD
726 9 1 3 days601 USD
Hello! I have reviewed your project and am ready to start working. I can guarantee excellent results in a short time.
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111 days601 USD
1098 12 0 2 111 days601 USD
Good day.
I have reviewed the technical assignment regarding the MVP of the strength exercise tracking system. The project has a clear architecture and well-defined requirements — we are ready to take it on.
We have experience in developing BLE solutions (Peripheral/Central architecture), synchronizing IMU sensors, real-time signal processing, and creating mobile applications for iOS/Android. We have also worked with firmware (BLE services, timestamp, buffering, OTA) and implementing motion detection algorithms (filtering, correlation, peak detection, drift compensation).
We have a team of embedded and mobile developers, so we can cover the entire cycle — from firmware to application. We work in stages with task decomposition and control milestones.
We are ready to discuss technical details (chipset, stack, packet format), estimate timelines and budget for the MVP.
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30 days601 USD
338 30 days601 USD
Ready to implement the project qualitatively and on time, need to discuss the details.
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30 days601 USD
362 30 days601 USD
I have experience working with BLE, IMU, and processing sensor data. I am ready to implement the firmware and mobile part: stream synchronization, correlation algorithm, and repeat detection. I will ensure connection stability and compliance with MVP requirements.
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30 days601 USD
307 30 days601 USD
Hello. I have a very large experience in implementing such applications and systems. There are a few questions regarding the project - we can discuss.
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15 days601 USD
5692 24 0 15 days601 USD
Hello! 👋
I do not just draw, but I DESIGN applications and platforms for over 5 years.
Please check my portfolio and confirm my expertise:
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