Support Arm Joint Torque Control Under External Disturbances
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Solution Overview
Problem
In medical observation apparatuses with force-controlled support arm systems, unintended external forces can disrupt the intended motion of the arm section, impairing user operability and making it difficult to achieve precise movements during surgical procedures.
Innovation Solution
A driving control method that controls the torque in joint sections of the arm section to keep external torque within a fixed range, compensating for disturbances such as those caused by the rigidity of cables, thereby ensuring a consistent operational feel and improved user control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force control is applied to the arm section to improve user operability, then the user can directly manipulate the arm section with more natural feedback, but external disturbances can still disrupt the intended motion and impair precision
Solution Approach 1:
The patent changes the control parameter from pure force control to a hybrid mode that incorporates both force control and position control. The control mode switching mechanism allows the system to transition between these modes based on operational needs, thereby maintaining ease of operation while improving motion precision by reducing the impact of external disturbances
Solution Approach 2:
The patent implements a feedback mechanism where the control section continuously monitors the arm section's state and adjusts the control mode accordingly. This feedback loop enables the system to detect when external disturbances occur and switch to a control mode that prioritizes position accuracy, thus resolving the contradiction between ease of operation and motion precision
2Ease of operation
If the arm section is made highly responsive to external forces, then user manipulation becomes more intuitive, but unintended external forces can cause unwanted motion and reduce control accuracy
Solution Approach 1:
The patent applies dynamics by making the control characteristics of the arm section changeable rather than fixed. The control mode can dynamically switch between force control (high responsiveness to external forces) and position control (high control accuracy) based on the operational context, thereby resolving the contradiction between manipulation intuitiveness and control accuracy
Solution Approach 2:
The patent changes the control parameter from a fixed force control setting to a variable control mode that can be adjusted between force control and position control. This parameter change allows the system to maintain high responsiveness when needed while ensuring control accuracy when external disturbances are present
Data Source
AI summary
A medical observation apparatus includes an imaging device that captures an observation target, an arm that supports the imaging device and includes multiple links joined to each other by multiple joints, and driving circuitry. The driving circuitry is configured to determine a control torque in at least one joint to be controlled from among the multiple joints and to control driving of the at least one joint based on the control torque such that an external torque acting on the at least one joint according to an operation on the arm is within a fixed range.