The Design
This device is fixed on one side of injured elbow, Accelero/Magnetometer, The sensors can provide the motion status of arm, with pattern matching arithmetic, the direction and force applied on the actuator shall be calculated and timely modulation for PWM control on motors. This can add extra power for arm movement and improve the life span for injured arms. Of course, reduce pains if the elbow is still not healed.
This is one kind of health care assistance machine, with gesture sensing and analysis. Same principle can apply for injured knees for free walking and exercise rehabilitation during recover stage for injured bone joints.
Unlike the notion of replace the function of people, this main purpose of the device is improvement in stead of replacement. This is more safe and reliable by means of small help by electrical driven motor.
Hardware and Software
FRDM-KV31, with 32-bit,120MHz CPU/DSP, 6 Axis Accelero/Magnetometer. The 6-axis matrix data in time span is collected by MCU via SPI, after calculation and transformation, the status of the arm is analysis. With pattern matching, the predicted next move is formed and feed a PWM signal to motor driver, the motor shall be turned according the motion of elbow. The turns of motor is delayed only after the arm in movement, reduce the delay time span can make people feel little on the delay. Such principle avoid the possibility of motor drive in opposite direction of real direction of arms.
Kinetics Design Studio shall be used in software development, with middleware such as RTOS to improve the Efficiency.
Key Issues To Be Considered
The challenge of hardware is the power matching and mechanical design. The reducer gearbox shall match the ratio of elbow movement with proper force and response time.
The challenge in software is the pattern matching. Gyro sensors provided more data than needed before proper data transformation and calculation. The result is only 2-D data with direction and scale of movement on timeline limitation. Therefore, the pattern matching arithmetic shall be proper design and calculated.
