Robotic Limb Resonance Velocity Amplification
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Solution Overview
Problem
Existing robotic limb systems for walking robots are limited in speed due to the lack of velocity amplifying structures and failure to exploit natural resonance properties, resulting in constrained walking or trotting gaits and high energy consumption.
Innovation Solution
A robotic limb structure that utilizes a primary driven link with secondary and auxiliary links, elastic trim elements, and a control system to leverage resonant characteristics for velocity amplification, along with a dual-state suspension system for efficient energy use and speed enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actuators are placed at each pivoting joint to directly control angular relationships, then control precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent extracts the actuator from each joint and relocates it to a single base location. Instead of having multiple actuators at hip, knee, and ankle joints, the system uses one base actuator that drives the entire limb through a tendon-like flexible transmission system, dramatically reducing the number of actuators from three per limb to one per limb
Solution Approach 2:
The patent introduces a flexible transmission medium (tendon-like element) as an intermediary between the base actuator and the distal limb joints. This intermediary transmits force and motion from the base actuator to multiple joints along the limb, enabling remote control without placing actuators at each joint location
2Ease of operation
If actuators are placed near the distal end of limbs to provide direct drive, then control authority is improved, but speed is reduced due to added mass that must be swung
Solution Approach 1:
The patent inverts the conventional actuator placement strategy by moving the actuator from the distal end to the base location. Instead of having the actuator follow the limb segment it controls, the actuator remains stationary at the base while controlling multiple segments through the flexible transmission system, eliminating the need to swing actuator mass during limb motion
Solution Approach 2:
The patent segments the limb into multiple rigid links connected by passive joints, with the flexible transmission system providing the active control element. This segmentation allows each limb segment to be lightweight and passive, while the single base actuator provides centralized control, separating the mass of the actuator from the moving limb segments
3Device complexity
If actuators directly control each joint without velocity amplification, then control simplicity is improved, but maximum speed is limited by actuator velocity
Solution Approach 1:
The patent employs resonant vibration of the limb structure to achieve velocity amplification. By driving the limb at its natural resonant frequency, the system amplifies the velocity of the distal limb segments relative to the base actuator velocity, enabling faster limb motion without requiring faster actuators
Solution Approach 2:
The patent changes the operational parameters of the limb system by operating in resonance rather than in a purely controlled manner. This parameter change allows the system to exploit dynamic effects and resonance to achieve velocity amplification, trading some control simplicity for significantly enhanced speed capability
4Force
If heavy actuators are placed at each joint, then torque capability is improved, but energy consumption increases due to the mass that must be accelerated and decelerated
Solution Approach 1:
The patent merges the functions of multiple actuators into a single base actuator. Instead of having separate actuators at hip, knee, and ankle joints each consuming energy, the system uses one actuator that provides torque to the entire limb through the flexible transmission system, reducing total energy consumption while maintaining torque capability
Solution Approach 2:
The patent enables the limb structure itself to serve the function of force transmission and amplification. The rigid limb segments and passive joints work together with the flexible transmission system to multiply the torque from the base actuator, eliminating the need for heavy actuators at each joint and reducing the energy required for acceleration and deceleration
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
Enables high-speed operation while reducing energy consumption by amplifying velocity and utilizing natural resonance, allowing robots to achieve faster speeds than prior art designs.
Implementation Method 1
Elastic trim elements are also provided to define a 'relaxed' state for the limb and to influence the resonance characteristics of the structure
Implementation Method 2
A control system is provided to control the force input to the limb. The force input will generally be non-linear. The control system takes advantage of the resonant characteristics of the structure as a whole.
Implementation Method 3
An alternate suspension state allows one or more degrees of freedom—such as a knee joint or a set of tendons which may cross many joints—to be selectively latched.
Data Source
AI summary
A robotic limb structure which is capable of achieving high speeds. In the context of a biped, the structure is used for a pair of hind limbs. The limb structure includes a primary driven link—such as a thigh pivoting about a hip joint in the case of a hind limb. Secondary links are pivotally connected to the primary driving link. Auxiliary links are provided to constrain the motion between the links. Elastic trim elements are also provided to define a “relaxed” state for the limb and to influence the resonance characteristics of the structure. The control system takes advantage of the resonant characteristics of the structure as a whole.