Servomechanism Control for Powered Exoskeleton Joints
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Solution Overview
Problem
Existing control systems for powered exoskeletal machines struggle to accurately map the force, position, and velocity of an operator to the vehicle's joint, leading to inefficiencies and potential violent movements when encountering obstacles.
Innovation Solution
A closed-loop servomechanism system that uses a pair of feedback actuators to transmit forces between the operator's input joint and the powered joint, with a force transducer and controller to adjust the powered actuator's power based on the sensed residual force, ensuring positional parity and controlled force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control system provides mapping of force, position and velocity from operator to vehicle joint, then operational control is improved, but system complexity increases due to multiple design complications
Solution Approach 1:
The patent implements a feedback system where a force transducer measures forces on the control joint and feeds this information back to a controller, which adjusts the powered actuator accordingly. This closed-loop feedback mechanism simplifies the control architecture by using direct force measurement rather than complex multi-parameter mapping, while maintaining ease of operation through intuitive force-based control.
Solution Approach 2:
The patent replaces complex mechanical control linkages with a hybrid system combining force transducers (sensing elements) and powered actuators (actuation elements). This substitution of mechanical complexity with sensor-actuator systems reduces the number of mechanical components while preserving operational control, directly addressing the contradiction between ease of operation and device complexity.
2Force
If huge forces are used to move vehicle joints, then powered actuation capability is improved, but risk of violent movements and safety issues increases
Solution Approach 1:
The force transducer continuously monitors forces on the control joint and provides feedback to the controller, which regulates the powered actuator's output. This feedback control prevents violent movements by detecting force anomalies and adjusting actuation accordingly, maintaining safety while preserving the capability to generate huge forces when needed for moving vehicle joints.
Solution Approach 2:
The system prepares for potential violent movements by implementing preliminary safety measures through the feedback control loop. The force transducer detects abnormal force conditions before they can cause violent movements, and the controller preemptively adjusts the powered actuator to prevent unsafe conditions, thus addressing the safety concern while maintaining actuation capability.
3Measurement precision
If positional parity is maintained between control joint and powered joint, then control precision is improved, but system complexity increases due to feedback mechanism requirements
Solution Approach 1:
The patent uses a force-based feedback mechanism rather than complex position-based feedback systems. The force transducer measures forces on the control joint, and the controller uses this force information to maintain positional parity between the control joint and powered joint. This force-centric approach simplifies the feedback system compared to traditional multi-sensor position feedback while achieving the same positional precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system allows operators to apply controlled forces to external objects, improving operational efficiency and safety by maintaining positional parity and reducing the risk of violent movements when encountering obstacles.
Implementation Method 1
a pair of feedback actuators, a first of the feedback actuators acting on the control joint and a second of the feedback actuators acting on the powered joint, the actuators operatively coupled to send and receive a feedback signal from each other, such that a force on the powered joint acts via the feedback cylinders upon the input joint and vice versa
Implementation Method 2
a force transducer for measuring a force on the control joint or within the feedback system
Implementation Method 3
a biasing member, arranged in parallel with the displacement sensor
Implementation Method 4
a damper arranged in parallel with the biasing member
Data Source
AI summary
A servomechanism and method of operating same are provider. The servomechanism may be used in walking vehicles or construction vehicles. An operator provides a force to an input joint which controls a powered joint of the vehicle. Force is detected in a feedback system between the powered joint and input joint to control the power to an actuator driving the powered joint.