Finishing Manipulator Torque Control With Parallelogram Arm Stiffness
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Solution Overview
Problem
Industrial robots face challenges in performing finishing tasks due to low rigidity, leading to processing deviations and requiring special end-effectors to prevent disturbances, limiting their effectiveness in automated finishing processes.
Innovation Solution
A manipulator with a base, arm, and actuators that include a parallelogram link structure and dynamic decoupling, using feed forward torque control based on self-weight effects to provide stable torque without position or force feedback, allowing for wider working ranges and improved stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If industrial robots are used for finishing works, then automation is achieved, but rigidity is low causing processing deviation
Solution Approach 1:
The manipulator arm is divided into multiple links connected by joints, with each link and joint optimized for specific functions. The parallelogram link set is segmented into first and second links with separate actuators, allowing independent control and compensation for rigidity issues in each segment while maintaining overall automation.
Solution Approach 2:
The manipulator employs dynamic decoupling between the first and second joints through the parallelogram structure, where the second joint provides leverage effect to compensate for rigidity variations. The feed forward torque control dynamically adjusts actuator forces based on predicted loads, maintaining precision during automated operation.
2Measurement precision
If closed servo systems are employed in industrial robots, then control precision is improved, but user accessibility is limited requiring special end-effectors
Solution Approach 1:
The manipulator uses feed forward torque control that calculates required actuator forces based on known system dynamics and desired trajectories. This open-loop approach with pre-calculated compensation maintains control precision while allowing direct user manipulation without restrictive closed servo systems, eliminating the need for special end-effectors.
3Stability of the object's composition
If parallelogram link structure is added to the manipulator, then stiffness and working range are improved, but device complexity increases
Solution Approach 1:
The parallelogram link structure merges the first and second links into a coordinated mechanism where the second link mirrors the first link's motion. This geometric constraint provides stiffness and stability while the shared actuator control reduces the number of independent control systems needed, balancing structural complexity with performance benefits.
4Device complexity
If feed forward torque control is used without position or force feedback, then system simplicity is maintained, but control accuracy may be compromised
Solution Approach 1:
The feed forward torque control calculates and applies the required actuator forces in advance based on the known dynamics of the manipulator and the planned trajectory. By pre-compensating for gravitational effects, inertial forces, and Coriolis forces, the system achieves accurate finishing work without requiring complex real-time feedback loops, maintaining simplicity while ensuring 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 solution enables uniform and smooth torque control, expanding the working range and overcoming limitations of traditional compliance control methods, resulting in more stable and efficient finishing processes.
Implementation Method 1
the second joint provides a leverage effect on the arm by the parallelogram structure
Implementation Method 2
a processor determining a driving torque of each of the plurality of actuators considering a self-weight effect of the manipulator
Data Source
AI summary
An embodiment of the present disclosure provides a manipulator for a finishing work, including: a base; an arm comprising a plurality of links, a plurality of joints connecting the plurality of links, and a plurality of actuators generating rotation of at least some of the plurality of joints; and a processor determining a driving torque of each of the plurality of actuators considering a self-weight effect of the manipulator and controlling the plurality of actuators based on the determined driving torque.