Robot Gravity Compensation Control for Joint Torque Limits
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Solution Overview
Problem
Space robot devices designed for gravity-free environments face limitations when operated on Earth due to exceeding torque limits in certain configurations, restricting their working area and necessitating an optimal strategy for gravitational force compensation.
Innovation Solution
A method involving both support devices and actuator control signals to compensate for gravitational forces, where a computer device calculates and distributes gravity-compensating signals to minimize joint torques, allowing for adjustable distribution between the robot and support devices to optimize torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the robot device is designed for gravity-free operation with smaller joints and actuators, then the device becomes more energy efficient and lighter, but the torque limits are exceeded when operated on Earth
Solution Approach 1:
The patent applies gravity compensation techniques where support devices generate counteracting forces to offset the gravitational load on the robot device. This allows the robot's joints and actuators, designed for space conditions, to operate within their torque limits on Earth by compensating for gravitational effects through external support systems
Solution Approach 2:
The patent introduces support devices as intermediary systems between the robot device and the gravitational field. These support devices act as mediators that provide gravitational force compensation, enabling the robot to operate on Earth without requiring redesign of its joints and actuators for terrestrial conditions
2Reliability
If support facilities like helium balloons are used to compensate for gravitational force, then the robot device can be supported on Earth, but the working area is limited and the system becomes more complex
Solution Approach 1:
The patent employs dynamic support devices that can adapt their support characteristics based on the robot's configuration and task requirements. The support system dynamically adjusts the compensation forces to enable a broader working area while maintaining torque limit compliance, overcoming the limitations of static support methods like fixed helium balloons
3Strength
If gravitational force compensation is provided only by support devices, then the robot joints are protected from overload, but the required torque in joints increases and working area is restricted
Solution Approach 1:
The patent segments the gravitational force compensation function between the robot device itself and external support devices. The robot's actuators provide active compensation through controlled movement, while support devices provide passive or semi-active support. This segmentation allows the system to maintain joint load protection while expanding the working area through coordinated action of both components
Data Source
AI summary
A robot device that has a robot element pivotable about a first robot joint is controlled by a method including the steps of: moving the robot element by an actuator; controlling the actuator by an actuator control device that sends control signals to the actuator; and supporting the robot device by a support device. gravity-compensating control signals are sent to the support device by a support control device. The support device is controlled such that a force and/or a moment is applied to the robot element via a force-applying element connected to the robot element. The force and/or moment compensates for the gravitational load acting on the robot element. To compensate for the gravitational force acting on the robot element, gravity-compensating second control signals are sent from the support control device to the support device, and gravity-compensating control signals are also sent from the actuator control device to the actuator.