Multi-Axis Non-Exoskeletal Rehabilitation Arm with Cable Drives
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Solution Overview
Problem
Current robotic rehabilitation devices are either too simplistic and limited, interfering with patients, or too complex and cumbersome, failing to provide sophisticated 2-D and 3-D rehabilitation exercises in a cost-effective, unobtrusive manner.
Innovation Solution
A multi-active-axis, non-exoskeletal rehabilitation device with a unique positional and orientational relationship to the patient, utilizing a cabled differential and special kinematics to shift power drives away from the patient's workspace, offering three degrees of freedom and enabling bi-manual rehabilitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high-DOF exoskeletal systems are used to provide sophisticated rehabilitation exercises, then the range of motion and rehabilitation capability are improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the power drives from the patient's workspace by using cable-driven transmission mechanisms. The actuators are located remotely at the base of the device, and their motion is transmitted to the robotic arm through cables and pulleys. This allows the robotic arm to have high DOF and rehabilitation capability without the complexity and bulk of multiple motors mounted on each link.
Solution Approach 2:
The patent introduces cables and pulleys as intermediary elements between the power drives and the robotic arm joints. These intermediaries transmit mechanical motion and force from the base-mounted actuators to the multiple joints of the robotic arm, enabling sophisticated 3-D rehabilitation exercises while keeping the device structure simpler and more cost-effective.
2Device complexity
If low-DOF systems are used to reduce cost and complexity, then the device simplicity is improved, but the range of motion and rehabilitation capability are limited
Solution Approach 1:
The patent transitions from planar (2-D) motion to three-dimensional (3-D) motion by adding vertical motion capability through the cable-driven mechanism. The robotic arm can move not only horizontally but also vertically, allowing it to guide the patient's limb through sophisticated 3-D rehabilitation exercises while maintaining device simplicity through remote actuation.
3Force
If exoskeletal systems wrap around the patient's limb to provide support, then the limb support capability is improved, but the device becomes more intrusive and uncomfortable
Solution Approach 1:
The patent removes the bulky motor assemblies from the robotic arm links and relocates them to the base of the device. This extraction eliminates the need for heavy components to be in contact with or near the patient's limb, reducing intrusiveness and improving comfort while maintaining the ability to provide necessary support forces through the cable transmission system.
4Power
If power drives are mounted on the robotic arm links to provide motion, then the actuation capability is improved, but the device footprint and interference with patient's workspace increase
Solution Approach 1:
The patent extracts all power drives from the robotic arm structure and consolidates them at the base of the device. The cable-driven transmission system transmits actuation capability from the base to multiple joints along the robotic arm, eliminating the need for motors mounted on each link and significantly reducing the device footprint and interference with the patient's workspace.
Data Source
AI summary
A robotic device for operation in association with an appendage of a user, wherein the appendage of the user has an endpoint, the robotic device comprising: a base; and a robotic arm attached to the base and having an end-point, the robotic arm having at least two active degrees of freedom relative to the base and being configured so that when the base is appropriately positioned relative to a user, the reference frame of the robotic device is oriented generally similarly to the reference frame of the user and motions of the endpoint of the appendage of the user are mimicked by motions of the endpoint of the robotic arm.