Wearable and convertible passive and active movement training robot: apparatus and method

Abstract

In respects of limitations and problems of motor function training devices, the present invention provides a wearable and convertible device and a method for controlling combined motor function training. This device integrates the functions of both passive stretching function in the existing CPM devices and additional active assistive training function. Without a force / torque sensor element in the device, the present passive stretching control can still be adapted to hypertonia (high muscle tone or stiffness of joints) of the limb, and the present active assistive control can still be implemented for enhancing voluntary active movement from patients. With such present method, much more applications of active assistive training are supported at substantially no additional cost. On the other hand, the safety of such stretching devices without using force / torque sensor is improved, which assists in increasing the efficiency of the device of the present invention.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention generally relates to a motor function training device for upper or lower extremity of people with neurological disorders or musculoskeletal injuries. This invention presents a simplified mechanical structure of wearable and convertible with a novel control method to conduct safe and effective joint stretching and active assistive guidance functions without using additional torque / force sensor.[0003]2. Description of Related Art[0004]Joint mechanical properties and movement control are important in functional activities and they may be affected in neurological disorders and musculoskeletal injuries, such as reduction in joint range of motion, increased stiffness, increased muscle tone, and impaired motor control. And neurological impairments, including stroke, spinal cord injury, multiple sclerosis and cerebral palsy are the leading causes of motor dysfunction. Brain damage caused by spasticity and contract...

AI Technical Summary

Benefits of technology

[0017]In respects of above limitations and problems, the present invention provides a wearable and convertible device and a method for controlling combined motor function training. This device integrates the functions of both passive stretching in said existing CPM devices and additional active assistive training. Without using a force / torque sensor element, the present passive stretching control can still be adapted to hypertonia (high muscle tone or stiffness of joints) of the limb, and the present active assistive control can still be implemented for enhancing voluntary active movement from patients. With present method, much more applications of active assistive training are supported at substantially no additional cost. On the other hand, the safety of such stretching devices without using force / torque sensor is improved, which assists in increasing the efficiency of the device of the present invention.

[0019]The present invention also provides a control method for performing active assistive and passive stretching training on said training device. Said method comprises the step of performing one or more modes according to the limb training requirement: 1) a mode for compensating inherent resistance force of said motor and gearing, in which the small change of angular position caused by the synchronous movement of the movement portion brought by the active movement of the limb is detected, and the motor driving portion is controlled to apply a torque that is merely enough to overcome the mechanical resistance force of the device so that the limb can move freely; 2) a mode for stretching, in which the change of current in the motor driving portion caused by a torque applied to the movement portion by the limb is detected, the detected change of current is passed through a low pass filter to obtain a smooth value, the rotating speed and range of the movement portion is adjusted according to the change of said filtered current so as to adjust the rotating speed and range of the limb for stretching the muscles of the hypertonic limb; 3) a mode for assisted training and resistance training, in which the change of angular position of the movement portion is detected via the position sensor, the motor is controlled to apply assisting torque or resistance torque that is respective in the same or opposite direction with the movement of the limb, so that assisted training or resistance training can be performed; and 4) a mode for inducing voluntary active movement, in which the change of current in the motor driving portion caused by a torque applied to the movement portion by the limb is detected, and the change of the torque caused by active movement of the limb is estimated according to the change of current, when the change is smaller than a threshold, the motor driving portion is controlled to make the limb do exemplary passive movement, and the movement of the limb is fed back to the patient. Then let the patient move freely, and the change of current in the motor driving portion caused by a torque applied to the movement portion by the limb is detected. According to the change of current, the change of the torque caused by active movement of the limb is estimated, resealed and fed back to the patient. The real time visual and auditory feedback of limb's movement keeps the patient engaged and challenged.

[0020]Compared to the existing technologies, the present invention provides a low cost active and passive training device with a simplified structure, and a corresponding control method for impaired limb rehabilitation. Innovations of the system are: (1) further simplify the system structure and components by reducing a force / torque sensor component. The device with simplified structure requires the present control method to detect the joint resistance and voluntary movement intention from a training joint, to accomplish similar functions, which greatly reduces the manufacturing costs. Excluding using electrical current of the motor driving portion as torque estimation, said force / torque sensor refers to a component and a structure used for force / torque measurement, such as stress and strain gauges, torque sensors, spring dynamometer and pressure sensors, etc.; (2) realize controlling the stretching speed and assistance level by detecting the change of angular position and current in the drive portion without an force / torque sensor. And implement the function of safe and self-adaptive passive stretching by using the invented method to overcome the high muscle tone or resistance; (3) invent the structure and control method which can achieve all five following integrated functions, and there is no existing training device which can implement such training combination of all five training modes:

[0021]Mode 1. The presented device can output high driving torque in passive stretching, which is enough to fight against hypertonia (high muscle tone or stiffness of joints). According to the detected change of current in the motor driving portion, the stretching speed and the stretching range of motion of movement can be adjusted and adapted to the change of said muscle tone and stiffness.

[0027]In summary, the present invention can not only free the physical therapist from the strenuous manual stretching, but also provide the effective and accurate stretching training function and induce the patient's voluntary movement. In addition, the present device can implement combined passive stretching and active assistive movement function, which is an essential factor for the motor function recovery on people with neurological disorders and musculoskeletal injuries.

[0028]Therefore, the device of the invention is capable of outputting both passive stretching and active assistive movement function so as to meet clinical requirements for motor function recovery on people with neurological disorders and musculoskeletal injuries. The invention proposes a low-cost design structure, so the patients can conveniently use in their own homes and increase their training frequency, so as to shorten their recovery cycle. Compared to previous methods, the invented method can greatly reduce the size, weight and manufacturing costs of the training system and the patient can use the low-cost training devices at home and in local clinics. And for acute patients, they can use the device for the rehabilitation training while in their early stage of recovery.

Problems solved by technology

Brain damage caused by spasticity and contracture will result in lasting effects in patients.

The hypertonus and reflex hyperexcitability disrupt the remaining functional use of muscles, impede the limb movement, and also cause severe pain.

However, the manual stretching is strenuous and the outcome is dependent on the experience and the subjunctive “end feeling” of the therapists.

2) Without assistance of any rehabilitation device or physical therapist, the patient may have difficulties to achieve or remain an active body movement continuously and stably and cause a delayed process of fully motor function recovery.

Furthermore, they could experience further joint injury due to lack of knowledge of rehabilitation or over excessive rehabilitation

3) Due to the shortage of therapist resources, patient may only receive limited infrequent therapy and the therapy effects may not be long-lasting.

On the other hand, setting a CPM machine too aggressively may risk injuring the joint because the machine controls the joint position or velocity without incorporating the resistance torque generated by the soft tissues.

Practically, advanced rehabilitation robots are too expensive for local clinic and home uses.

Functionally, rehabilitation robots often focus on active assistive movement training and do not provide integrated passive and active movement therapy.

However, the implementation of system function and control is dependent on the precision of an additional force or torque sensor, which increases the system cost and makes it not suitable for a wide range of clinical and home use.

Functionally, such rehabilitation training devices only focus on active assistive movement training and exclude effective passive stretching function due to the limitation of the mechanical structure.

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