Robot Arm Communication Paths for Compact Surgical Systems
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Solution Overview
Problem
Designing a robot arm that balances the requirements of minimal size, circular symmetry, high torque, stiffness, low backlash, and efficient communication while minimizing the size and weight, particularly for surgical robots, is challenging due to the need for effective sensor and motor communication with a central control unit.
Innovation Solution
A robot arm with a compound joint featuring coupler elements and revolute joints, equipped with rotational position and torque sensors, and a communication system where data from sensors is encoded into packets and transmitted using a packet-based protocol, with physical data links running within the arm to optimize space and communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the arm size is minimized to allow multiple robot arms to work in close proximity, then the space efficiency improves, but the cable management and communication path arrangement becomes more difficult
Solution Approach 1:
The patent divides the communication system into multiple independent communication units, each borne by different limbs of the robot arm. Each communication unit independently encodes and transmits sensor data, eliminating the need for complex cable routing through the entire arm structure. This segmentation allows for simplified cable management while maintaining compact arm dimensions.
Solution Approach 2:
The patent transitions from a centralized communication architecture to a distributed architecture where communication units are positioned at multiple locations along the arm. This spatial distribution across different dimensions allows data transmission without requiring cables to traverse the entire arm length, thus reducing cable complexity while maintaining small arm size.
2Weight of moving object
If the distal portion of the arm is made lightweight to reduce force requirements, then the energy consumption decreases, but the structural stiffness and torque capacity may be compromised
Solution Approach 1:
The patent applies different structural qualities to different parts of the arm. The distal portion is designed to be lightweight with minimal components, while the proximal joints and coupler elements maintain higher structural integrity for torque generation. This local differentiation allows the distal end to be light without compromising the overall torque capacity of the arm.
Solution Approach 2:
The patent employs dynamic torque sensing and control where torque sensors continuously monitor the actual torque requirements at each joint. The control system adjusts motor output in real-time based on sensed torque, allowing the arm to maintain adequate torque capacity only when needed, thus enabling a lighter distal structure without sacrificing operational capability.
3Measurement precision
If multiple sensors are installed in the distal portion to provide high measurement precision, then the control accuracy improves, but the device complexity and weight increase
Solution Approach 1:
The patent employs multi-functional sensor units that can detect multiple parameters (position, torque, and potentially other physical quantities) using a single integrated sensor package. This universal sensing approach provides high measurement precision for multiple variables without proportionally increasing the number of separate sensor components, thus reducing system complexity.
Solution Approach 2:
The patent replaces complex mechanical sensing systems with electronic sensors that provide high-precision measurements. Instead of using mechanical linkages, gears, or physical measurement devices, the system uses electronic sensors coupled with digital communication units to sense and transmit data, thereby achieving high measurement precision with reduced mechanical complexity.
4Device complexity
If a centralized communication system is used to simplify data transmission, then the communication architecture is simpler, but the cable length and weight increase
Solution Approach 1:
The patent segments the communication system into multiple independent communication units distributed along the arm limbs. Each unit independently encodes and transmits data from its associated sensors, eliminating the need for long centralized cables running the full length of the arm. This segmentation dramatically reduces total cable length and weight while maintaining communication functionality.
Solution Approach 2:
The patent transitions from a single centralized communication node to multiple distributed communication units positioned at different locations along the arm. This spatial distribution allows data transmission to occur locally at each position rather than requiring long-distance cable runs, thus reducing cable weight while maintaining communication effectiveness.
Data Source
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AI summary
A robot arm having a compound joint between a first limb of the arm and a second limb of the arm, the second limb of the arm being distal of the first limb, the arm comprising: a coupler element coupled to the first limb of the arm by a first revolute joint having a first rotation axis and to the second limb of the arm by a second revolute joint having a second rotation axis; first and second rotational position sensors for sensing the configuration of the arm about the first and second joints respectively; first and second torque sensors for sensing the torque applied about the first and second joints respectively; a control unit for controlling the operation of the arm; a first communications unit borne by the arm and located proximally of the coupler and a second communications unit borne by the arm and located distally of the coupler, each communications unit being capable of encoding data received from one or more of the position and/or torque sensors in a first data format into data packets and transmitting those packets to the control unit in accordance with a packet-based data protocol different from the first data format; wherein the first position sensor is connected by a physical data link running within an exterior wall of the first limb to the first communications unit to so as to pass data representing sensed position about the first joint to the first communications unit for encoding and the first torque sensor is connected by a physical data link running within an exterior wall of the second limb to the second communications unit to so as to pass data representing sensed torque about the first joint to the second communications unit for encoding.