Master-Slave Manipulator Redundant Joint Control
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Solution Overview
Problem
Master-slave manipulators with redundant joints face complex inverse kinematics calculations, especially when the remote manipulation device and slave arm have different degrees of freedom, making it difficult for operators to control effectively.
Innovation Solution
A master-slave manipulator system that includes a remote manipulation device with multiple degrees of freedom, a slave manipulator with redundant joints, and a control unit that calculates orientation changes and selectively drives joints in redundancy relationships to simplify the inverse kinematics calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the degree of freedom of the slave arm is made equal to the degree of freedom of the remote manipulation device and joints are controlled based on a one-to-one basis, then the inverse kinematics calculation is simplified, but it becomes difficult to operate a remote manipulation device having many degrees of freedom with one hand
Solution Approach 1:
The patent extracts and designates a specific joint (the joint closest to the leading end) as the roll axis joint for performing rolling operations. By separating the rolling function from the general degree of freedom control, the system simplifies the inverse kinematics calculation while maintaining ease of operation. The designated roll axis joint handles the rolling motion independently, allowing other joints to focus on position and orientation control.
Solution Approach 2:
The patent applies local quality by assigning specific functional characteristics to specific joints. The joint closest to the leading end is designated with roll axis characteristics, while other joints maintain their original functional assignments. This localized functional differentiation simplifies the overall control strategy by ensuring that rolling operations are handled by a dedicated joint rather than requiring complex coordination across multiple joints.
2Ease of operation
If multiple joints are operated to collide with a circumjacent organ during rolling operation, then the rolling function is achieved, but the risk of tissue damage increases
Solution Approach 1:
The patent extracts the rolling function and assigns it to a specific designated joint (the joint closest to the leading end). By isolating the rolling operation to a single joint rather than requiring multiple joints to work together, the system eliminates the risk of joint collisions with circumjacent organs while maintaining the rolling capability needed for suturing operations.
Solution Approach 2:
The patent introduces a control mechanism that acts as an intermediary between the remote manipulation device and the slave arm joints. The control unit calculates the required joint movements based on the designated roll axis joint's position and orientation, serving as a mediator that prevents direct collisions between multiple joints and surrounding tissues while achieving the desired rolling motion.
3Measurement precision
If a redundant joint is provided at the leading end portion for positioning and posturing, then the precision of leading end control is improved, but the inverse kinematics calculation becomes complex
Solution Approach 1:
The patent applies local quality by designating a specific joint (the joint closest to the leading end) as the roll axis joint with specialized rolling characteristics. This localized functional assignment allows the redundant joint to provide precise positioning and posturing control without complicating the inverse kinematics calculation, as the designated joint handles the rolling function independently.
Solution Approach 2:
The patent changes the control parameters by designating a specific joint as the roll axis joint and using its position and orientation as the primary parameters for controlling rolling operations. This parameter change simplifies the inverse kinematics calculation by reducing the complexity of coordinating multiple joints for rolling motions, while still achieving precise leading end control through the redundant joint.
Data Source
Figure 1
Figure 2A~2B
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AI summary
A master-slave manipulator includes a remove manipulation device (100), a slave manipulator (300), and a control unit (200). The remote manipulation device (100) gives an operating command corresponding to a plurality of degrees of freedom. The slave manipulator (300) includes a plurality of joints corresponding to the degrees of freedom and a redundant joint is included among the joints. The control unit (200) controls operations of the joints in accordance with the operating command and calculates an orientation change of the remote manipulation device from the operating command at predetermined time intervals and selects and drives one of the joints in redundancy relationship among the joints in accordance with the orientation change.