Lower Limbs Force Augmentation Exoskeleton

Project Title

Lower Limbs Force Augmentation Exoskeleton

Project Area of Specialization Biomedical EngineeringProject Summary Summary:

Lower limbs Force Augmentation exoskeletons are the type of exoskeletons that increase (amplify) force in lower limbs including knees with the help of external actuators like motors to assist biomechanical motion. The project's main goal is to create a lower limb knee exoskeleton that can help crippled people. Actuators will support the movement of the human wearing the exoskeleton. The left and right leg exoskeletons will be linked to the supporting structure. The device will provide sit-to-stand and stand-to-sit movements using the control mechanism. This assistive device can be utilized to help provide movements to disabled persons.

Mechanical design, actuation system, and control method are three aspects of robotic exoskeletons to evaluate. We always wanted to work on a project that covers these aspects and deals to solve the problems faced by our aged community.

The ability of humans to perform different physical tasks is limited. They need some external support to do daily tasks more properly and efficiently. Likewise, an industrial worker continuously sits and stands according to the requirement of work. This continuous motion produces fatigue and pressure on the knees of workers. So, there is a need for some external support that can lower pressure and stress on the knees to some extent. For this purpose, we are designing an exo-skeleton specifically for knees that will help to reduce stress on the knee joint. The main objective of our knee exoskeleton is to provide partial force augmentation at the knee joints of the wearer.

Partial augmentation means that if a person’s knee produces 45 N-m torque then our knee exoskeleton will provide 15-20 N-m torque. Moreover, our knee exoskeleton is not only limited to industrial workers but it can also be used by elderly people and can be used for military purposes. Our exoskeleton will help soldiers to carry heavy loads easily.

Project Objectives Objectives:

    Following are the objectives of our final year project:

• Design of lower limb exoskeleton.
• Fabrication of exoskeleton.

Force augmentation of lower limbs (on knee joint) using feedback control method.

Project Implementation Method

Implementation Method:

As our exoskeleton is only targeting the human knees i.e., provides support to the knees by producing the required amount of torque. As we are using dc gear motors at both knees to provide torque. To find the required amount of torque we are using a flex sensor at both knees.

As flex changes its resistance value upon bending. We are using these values to actuate our motors by mapping the resistance value to a degree angle through Arduino code.

Our exoskeleton will assist in sit (90 degrees) to stand (180 degrees) movement of humans. For accurate positioning, a PID controller is used. Through feedback, the mechanism will be controlling the actuation of motors to achieve the required degree as sensed by the flex sensor. 

Benefits of the Project Benefits:

    Following are the benefits of our project:

1. Help the elderly in performing sit-to-stand motion
2. Help industrial workers who have to perform various tasks in the squat position.

Rehabilitation of partially disabled people. (disability can be because of any reason 

Technical Details of Final Deliverable Technical details:

    Our final deliverables are as follows:

1. Exo-frame with a Factor of Safety of 1.25 when knee joint provides additional torque of 25Nm.
2. Exoskeleton will be manufactured using aluminum-1100
3. Esp32 will be used as a controller which has a 10-bit resolution ADC.
4. Flex sensor having operating variable resistance between 10 - kilo Ohms to 110 - Kilo Ohms will be integrated.
5.  Variable resistor of 1.5 Kilo Ohms will be used as feedback sensor for exoskeleton's 
6. 2 DC gear motors operating at 14 volts and drawing maximum current of 3.5 Amperes will be used. Each motor is capable of providing 20 - 25 Nm torque at max.
7. 2 Li - ion batteries of 16Volts and 5000mAh each are used in our system.
8. IBT-2 H-bridge modules will be used for driving the DC gear motors

Final Deliverable of the Project Hardware SystemCore Industry EducationOther Industries Others , Health Core Technology Wearables and ImplantablesOther Technologies RoboticsSustainable Development Goals Good Health and Well-Being for PeopleRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	55810
Esp - 32	Equipment	2	1250	2500
Flex Sensor	Equipment	2	3200	6400
IBT 2	Equipment	2	1800	3600
Printed Circuit Board	Equipment	2	2000	4000
Motor	Equipment	2	6500	13000
Aluminum 1100	Equipment	7	350	2450
Aluminum Machining	Equipment	1	19000	19000
Capacitors	Equipment	15	3	45
resistors	Equipment	5	3	15
Solder Iron	Miscellaneous	450	1	450
Female headers	Equipment	50	2	100
wires	Equipment	50	10	500
Report Printing	Miscellaneous	1250	3	3750