Japanese automakers have been developing robotics both for manufacturing and other uses. Honda Motor Co.’s Asimo humanoid can run and dance, pour a drink, and carry on simple conversations, while WelWalk is more of a robotics system than a stand-alone robot. And Toyota is introducing a wearable Robotic leg brace designed to help partially paralyzed people walk. See video below.
Brushless & DC Servo Motor Used in Biomedical Exoskeletons
The gadget is designed to be worn on one leg at a time for patients severely paralyzed on one side of the body due to a stroke or other ailments. These Exoskeletons are wearable robotic devices that work with a user to regain mobility or assist/stabilize limbs, helping minimize fatigue and injury. This results in strengthening or replacing muscles for human motion.
Exoskeletons can be driven in many ways, but most commonly, they are electrically, mechanically, or hydraulically driven. The exoskeleton’s motors, sensors, and servo drives act as components of the human body. The nervous system, or in this case, the servo drives, instructs the motors to move as the human brain does with muscles. The encoders monitor and respond to the motion.
Mechanics
185 million people worldwide are estimated to use a wheelchair. Performing activities of daily living (ADL) is a challenge for people affected by muscle weakness or neurologic disorders, like paraplegia. Crutches and wheelchairs provide help to perform ADL.
Given how common paralysis due to stroke happens more prevalent in a fast-aging world, it is only a matter of time before the use of robotic aids for walking and rehabilitation shall one day prove more definitive than what a human therapist can do in the domestic environment. These exoskeletons commonly use miniature brushless DC motors with additional products such as gearboxes for attaining high torque and encoders for positional feedback, whereby the overall temperature of the robot can remain stable and low.
Typically, the requirements of these applications include high torque, long battery life, and the ability to work under load, e.g. in a seated position or on a staircase. To assist people who experience constant or temporary, partial immobility, such biomedical exoskeletons require a combination of ultra-small servo drives, high torque density motors, and precision encoders to be compact and flexible for increased wearability.
The very low heat generation of our ASSUN SERVO drive allows the robot to remain wearable at all times. This tiny servo drive is 10.3 mm tall and drives an RMS current of 10 A, with a PWM commutation frequency up to 200 kHz. The standby power consumption is only 1.2 W, making it a superior solution for battery-powered devices. Our motors have thin cross-section form factors to accomplish tight integrations to the exoskeleton-body.
Assistive Drives
Users of such exoskeletons need to have complete control over their locomotion, so the movement controls must be easily accessible and intuitively designed. These devices do not always encourage the normal use of muscles, leading to disuse and further deterioration of lower-limb muscle function for ADL.
In contrast, assistive lower-limb robots have the potential to support ADL and to encourage active participation of the user, making them valuable additions to or replacements of wheelchairs and crutches. While dynamic models of exoskeletons must deliver high torque, especially when walking up and down stairs.
Model-based control method utilizes a dynamic exoskeleton model to compensate for its dynamics. A high level of dynamics is required, as the motors must constantly change the direction of rotation due to the walking movement. At the same time, a compact design that takes up as little space as possible, using materials as lightweight, so that the user can pass through any door without much difficulty.
Assun Motor designs, manufactures and distributes high-performance DC driving systems to offer total solutions for precise driving and motion control applications.
These products include:
1. Brushless Coreless motors
2. Brushed Coreless motors
3. Planetary Gearbox
4. Encoders
5. Servo Motors
6. Servo controller and Speed drivers
7. Brakes
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