Arm-Mapped Manipulator Control Without Visual Sensors
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Solution Overview
Problem
Conventional manipulators require visual sensors or additional equipment for determining a user's arm location and posture, leading to increased manufacturing costs and limited ability to accurately follow user movements due to lack of one-to-one mapping of links.
Innovation Solution
A manipulator with a plurality of links corresponding to an upper arm, fore arm, and hand, equipped with motors for rotating the links, a communication interface, memory, and a processor that controls the motors based on rotation angle information and sensing values from external sensors to achieve precise posture control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual sensors or additional equipment are installed to determine user's arm location and posture, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces visual sensors and additional equipment with an inertial measurement unit (IMU) that uses mechanical sensing elements (accelerometers, gyroscopes, magnetometers) to determine arm location and posture. This substitution reduces device complexity while maintaining measurement precision by using compact integrated circuits instead of bulky optical systems.
Solution Approach 2:
The patent creates a virtual model of the user's arm by mapping IMU sensor data to manipulator link positions through inverse kinematics. This virtual representation allows the system to track arm movement without requiring direct visual observation, reducing the need for complex sensing equipment while maintaining accurate position determination.
2Device complexity
If links are not mapped with links of user's arm one to one, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent segments the arm tracking into independent rotational components at each manipulator joint. Instead of mapping entire arm segments to manipulator links, it measures rotation angles at each joint using IMU sensors and controls corresponding motors independently. This segmentation maintains precision by treating each degree of freedom separately while reducing overall system complexity.
Solution Approach 2:
The patent changes the control parameters from absolute position mapping to relative rotation angle measurement. By measuring angular displacement at each joint rather than absolute position of arm segments, the system achieves accurate movement following with a simpler structure that doesn't require one-to-one link mapping.
3Ease of operation
If quaternion information from sensor is used to assume hand posture, then ease of operation is improved, but measurement precision deteriorates due to cumulative posture errors
Solution Approach 1:
The patent segments the posture determination into independent joint rotation measurements rather than calculating overall arm posture from a single quaternion. Each joint's rotation angle is measured independently by IMU sensors at that joint, preventing cumulative errors from propagating through the kinematic chain while maintaining ease of operation.
Solution Approach 2:
The patent implements feedback by continuously measuring rotation angles at each joint using IMU sensors and using these measurements to directly control corresponding motors. This real-time feedback loop at each joint prevents error accumulation by constantly correcting based on actual sensor data rather than propagating errors from previous calculations.
Data Source
AI summary
A manipulator and a method for controlling the manipulator are disclosed. The manipulator includes: a plurality of links respectively corresponding to a user's upper arm, fore arm, and hand, a plurality of motors rotating the plurality of links, a communication interface comprising communication circuitry, a memory storing at least one instruction, and a processor configured to execute the at least one instruction, wherein the processor is configured to: based on first rotation angle information for motors corresponding to the upper arm and the fore arm among the plurality of motors, obtain information for a body frame of a link corresponding to the fore arm, obtain equilibrium angle information that positions the body frame in equilibrium with a specified reference frame, based on receiving a sensing value indicating the posture of the hand from an external sensor through the communication interface, obtain second rotation angle information for motors corresponding to the hand among the plurality of motors based on the sensing value and the equilibrium angle information, and control the motors corresponding to the hand based on the second rotation angle information.