Spring-Compensated Robot Joint for Variable Payload Gravity Balance
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Solution Overview
Problem
Conventional robotic manipulators lack the ability to dynamically adjust the gravity compensating torque applied by springs when the payload changes, leading to increased actuator efforts and reduced safety and robustness during collisions.
Innovation Solution
The robotic manipulator incorporates a four-bar linkage mechanism with gravity compensating springs, a spring adjustment mechanism, and a spring adjustment actuator that dynamically alters the position of spring attachment points to adjust the lifting force and torque in real-time, accommodating changing payloads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If highly geared electric motors are used to increase torque, then torque output is improved, but apparent inertia increases reducing safety and robustness during collisions
Solution Approach 1:
The system dynamically adjusts the spring pre-load force based on payload weight detection. When payload changes are detected by sensors, the control system modifies the pre-load force applied by the gravity compensating spring, allowing the system to adapt its mechanical properties in real-time rather than being fixed with high gearing throughout.
Solution Approach 2:
The invention changes the mechanical parameters of the system by adjusting the spring pre-load force according to payload conditions. This allows the apparent inertia and torque characteristics to be optimized for different operating conditions, reducing the need for consistently high gearing that would increase apparent inertia during all operations.
2Use of energy by moving object
If gravity compensating springs are used to offset gravity torque, then actuator effort is reduced, but the ability to dynamically adjust to payload changes is lost
Solution Approach 1:
The system incorporates sensors to detect payload weight changes and feeds this information back to the control system. Based on this feedback, the control system dynamically adjusts the spring pre-load force, enabling the gravity compensating mechanism to adapt to varying payload conditions while maintaining reduced actuator effort.
Solution Approach 2:
The gravity compensating spring system with adjustable pre-load force essentially serves itself by automatically adapting to payload changes through the control system. The system self-regulates the compensation force based on detected payload conditions, eliminating the need for manual reconfiguration and maintaining energy efficiency across different operating scenarios.
3Device complexity
If fixed spring pre-load force is used to compensate gravity, then device complexity is reduced, but productivity decreases due to increased actuator efforts
Solution Approach 1:
The system transitions from a static spring pre-load force to a dynamic adjustment mechanism controlled by a processor. This dynamic control enables the system to optimize actuator efficiency for different payload conditions, significantly improving productivity despite the increased complexity of the control system.
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 solution enables the robotic manipulator to maintain gravity balance with dynamically varying payloads, reducing the actuator efforts needed to accelerate and manipulate payloads, and enhancing safety and robustness by actively managing torque.
Implementation Method 1
at least one gravity compensating spring coupled between two links of the four-bar linkage mechanism at two different spring attachment points to provide a lifting force (Fb) in a direction opposing a gravitational force (Fg) on the payload
Implementation Method 2
a spring adjustment actuator configured to adjust the position of the spring attachment point by translating the spring attachment point along an axis that is parallel to the side link
Implementation Method 3
a four-bar linkage mechanism including an upper link arranged parallel to a lower link, and a first side link arranged parallel to a second side link coupled between the upper and lower links at distal ends
Data Source
AI summary
A robotic manipulator comprises a plurality of spring compensated joints, each including a four-bar linkage mechanism, a gravity compensating spring, a spring adjustment mechanism, a spring adjustment actuator and an inertial actuator. The gravity compensating spring is coupled between two links of the four-bar linkage mechanism at two different spring attachment points to provide a lifting force opposing a gravitational load force. The spring adjustment mechanism is coupled to alter a position of one of the spring attachment points. The spring adjustment actuator is coupled to move the spring adjustment mechanism to alter the position of the spring attachment point and adjust the amount of lifting force provided by the spring. The inertial actuator is coupled between links of the four-bar linkage mechanism to effectuate rotational movement of the four-bar linkage mechanism and apply an adjustable amount of force to accelerate and manipulate a payload handled by the robotic manipulator.