Continuum Robot Bending Control for Early Path Following
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Solution Overview
Problem
Existing continuum robot control methods fail to improve operability due to discrepancies between the operator's intention and the robot's shape, especially when the displacement of the base unit is smaller than the length of the bending section, making it difficult for the robot to enter a target route.
Innovation Solution
A continuum robot with a base unit, distal and follow-up bending sections driven by independent wires, and a control system that adjusts the bending angles of the follow-up section based on the forward movement and changes in the distal section's target angle, using a profile of bending angles to ensure smooth transition and alignment with the intended path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bending shape of the leading bending section is propagated to the following bending section only when the base unit moves forward by the length of a bending section, then the control method is simple, but the operability of the continuum robot deteriorates because a discrepancy between the intention of an operator and the shape of the continuum robot becomes larger
Solution Approach 1:
The patent applies preliminary action by enabling the follow-up bending section to start bending before the base unit completes its full movement distance. The control unit calculates and applies a preliminary bending angle based on the current displacement amount, allowing the robot to proactively prepare for the intended path rather than waiting for complete base unit movement. This reduces the lag between operator intention and robot response.
Solution Approach 2:
The patent implements dynamics by making the bending angle control adaptive and continuous rather than fixed and discrete. The control unit dynamically adjusts the bending angle of the follow-up bending section based on the real-time displacement amount of the base unit, creating a smooth, continuous control system that responds fluidly to operator inputs rather than in discrete steps.
2Device complexity
If the bending shape propagation is executed only after complete base unit movement, then the control timing is simple, but it becomes difficult for the continuum robot to enter a target route
Solution Approach 1:
The system performs preliminary bending action on the follow-up section before the base unit completes its movement. The control unit calculates a preliminary bending angle that allows the robot to start curving in advance, ensuring it can successfully enter the target route rather than waiting until the last moment when the full movement distance is achieved.
Solution Approach 2:
The patent implements feedback by continuously monitoring the displacement amount of the base unit and using this information to dynamically adjust the bending angle of the follow-up bending section. The control unit receives feedback on the current position and adjusts the bending profile accordingly, ensuring the robot maintains the correct trajectory to enter and follow the target route.
3Speed
If the target bending angle changes before the displacement reaches the bending section length, then the responsiveness to operator input improves, but the existing control method cannot handle this case
Solution Approach 1:
The patent applies dynamics by creating a control system that is adaptive to varying displacement amounts. The control unit dynamically calculates the appropriate bending angle based on the current displacement, allowing the system to handle any displacement value rather than being limited to fixed intervals. This enables responsive control at any point in the movement cycle.
Solution Approach 2:
The patent implements parameter changes by making the bending angle a continuous function of displacement amount rather than a fixed value. The control unit adjusts the bending angle parameter based on the current displacement state, allowing smooth transitions and responsive control as the displacement parameter changes, rather than being constrained by discrete movement intervals.
Data Source
AI summary
In a wire-driven continuum robot, in accordance with a profile of a first bending angle regarding a bending angle of a follow-up bending section that corresponds to a forward movement of a continuum robot, and is set in accordance with an input first target bending angle of a distal bending section, a bending angle of the following-up bending section is controlled to reach the first target bending angle. Before a movement amount of a forward movement reaches a first movement amount, the control is performed as follows. More specifically, a profile of a second bending angle that is different from the profile of the first bending angle is set, and by a further forward movement of the continuum robot, a bending angle of the following-up bending section reaches the second target bending angle in accordance with the profile of the second bending angle.