Robot Arm Communication Layout for Compact Compound Joints
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Solution Overview
Problem
Designing a robot arm that balances the requirements of being compact, capable of high torque, stiff, and efficient in communication while minimizing backlash and maintaining a circularly symmetrical profile for surgical procedures is challenging, especially in arranging sensors and motors for communication with a central control unit.
Innovation Solution
A robot arm with a compound joint system featuring coupler elements and revolute joints, equipped with position and torque sensors, and a dual communications unit system that encodes data from sensors into packets and transmits them using a packet-based protocol, allowing efficient data transmission within the arm's limited space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the distal portion of the robot arm is minimized, then multiple robot arms can work in close proximity and the arm can perform a wider range of surgical procedures, but the arrangement of sensors and motors with a central control unit becomes more difficult and space is more constrained
Solution Approach 1:
The robot arm is divided into multiple limbs (first limb, second limb, third limb) with a compound joint system. Each limb can be independently positioned and controlled, allowing the distal portion to be minimized in size while maintaining functionality. The segmentation enables flexible arrangement of sensors and motors across different limbs rather than concentrating them in one location.
Solution Approach 2:
The patent employs a nested structure where the third limb is positioned within the compound joint formed by the first and second limbs. The coupler element and revolute joints create a compact nested arrangement that minimizes the overall volume of the distal portion while accommodating all necessary sensors and motors in a space-efficient manner.
2Weight of moving object
If the distal portion of the robot arm is made lightweight, then the force required by proximal joints is reduced, but the arm must still deliver high torque to carry heavier tools and achieve high acceleration
Solution Approach 1:
The robot arm implements different quality characteristics in different locations: the distal portion (third limb and tool) is minimized in weight for reduced proximal joint force requirements, while the compound joint system with high-precision revolute joints and coupler elements is designed to deliver high torque when needed. The local quality principle allows the arm to be lightweight overall while maintaining high torque capability at the joint level.
Solution Approach 2:
The patent employs composite construction in the limb structures, combining lightweight materials with high-strength components. The limbs are designed to be as light as possible while the compound joint system incorporates robust mechanical elements capable of delivering high torque, creating a composite structure that balances weight and strength requirements.
3Volume of moving object
If the communication paths for sensors and motors are arranged to minimize space usage, then the arm size is reduced, but the data transmission efficiency and reliability may be compromised
Solution Approach 1:
The communication system is segmented into multiple independent communication paths distributed across the different limbs. Each limb has its own sensors and communication units, allowing data to be transmitted through multiple separate channels rather than a single path. This segmentation maintains communication reliability while accommodating the compact arm size, as each segment can operate independently.
Solution Approach 2:
The patent transitions from a centralized communication architecture to a distributed multi-dimensional communication network. Communication units are positioned at different locations (proximal and distal of the coupler) across multiple limbs, creating a three-dimensional communication topology that is more space-efficient and reliable than traditional linear arrangements.
Data Source
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.