Surface-Mounted Force Sensing for 3D Robot Motion Control
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Solution Overview
Problem
Current methods for determining and controlling forces on bodies, such as industrial robots or cobots, are limited by indirect measurement, sensitivity variations due to position, high costs from torque sensors, and restricted movement options, making programming and control processes inefficient and costly.
Innovation Solution
A device with sensor elements attached to the body surface, capable of directly measuring forces in multiple spatial directions, combined with an evaluation/control unit to calculate and control movements based on these forces, allowing for intuitive programming and enhanced redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are installed in the axles to directly measure torques, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The sensor element is divided into multiple individual sensor elements (at least three) arranged in a specific geometric configuration. Each individual sensor element measures force in a specific direction, and through evaluation unit processing, these measurements are combined to determine the total force vector acting on the body, eliminating the need for complex torque sensors on each axle.
Solution Approach 2:
The patent introduces an evaluation unit that acts as an intermediary between the simple surface-mounted sensor elements and the force determination system. This evaluation unit calculates the force components by processing signals from the individual sensor elements, effectively mediating between simple measurement components and accurate force measurement without requiring complex torque sensors.
2Measurement precision
If multiple torque sensors are attached to each axle for direct torque measurement, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive torque sensors with cheaper surface-mounted sensor elements that can be easily attached and detached. These sensor elements are designed to be cost-effective alternatives, providing sufficient measurement capability without the high cost of traditional torque sensors installed in each axle.
Solution Approach 2:
Instead of using one expensive torque sensor per axle, the system segments the measurement function across multiple inexpensive sensor elements mounted on the body surface. This segmentation allows the use of cheaper components while achieving the same measurement objective through geometric arrangement and signal processing.
3Ease of operation
If 3D joysticks are attached to the body for movement control, then ease of operation is improved, but adaptability decreases due to limited degrees of freedom
Solution Approach 1:
The patent transitions from controlling movement in limited directions (as with 3D joysticks) to measuring and controlling force vectors in three-dimensional space. By using multiple sensor elements arranged in specific geometric configurations, the system captures force components in multiple directions simultaneously, enabling full 6-DOF control capability.
Solution Approach 2:
The sensor element design provides multi-functionality by measuring force components in multiple spatial directions simultaneously. A single sensor element with multiple individual sensors can determine the complete force vector (Fx, Fy, Fz), making it a universal measurement device that works for any movement direction, replacing the need for multiple specialized control devices.
4Ease of operation
If sensor elements are attached to the body surface for direct force measurement, then ease of operation is improved, but measurement precision may worsen due to leverage effects
Solution Approach 1:
The evaluation unit processes the raw sensor data with knowledge of the sensor element's geometric configuration and its position relative to the body's center of rotation. This feedback processing compensates for leverage effects by calculating the actual force applied at the body surface, correcting for the moment arm effects that would otherwise degrade measurement accuracy.
Solution Approach 2:
The system changes the parameters used for force determination by considering not just the sensor readings but also the geometric parameters (distances, angles, orientations) of the sensor element relative to the body. By incorporating these geometric parameters into the calculation, the system transforms simple surface force measurements into accurate representations of the actual applied force, compensating for leverage effects.
Data Source
AI summary
A device for determining, in at least three spatial directions, a force acting on a body includes at least one sensor element for attaching to the surface of the body, which element includes at least three individual sensor elements, each individual sensor element being designed to determine an individual force in one direction, or which includes at least one individual sensor element which is used to determine an individual force in three spatial directions, and an evaluation/control unit which records the individual force determined by each individual sensor element and is designed to calculate the force acting on the sensor element in at least three spatial directions by projecting the individual forces onto a virtual point of the sensor element. A method for determining a force acting on a body in at least three spatial directions and a method for controlling the movement of a body is disclosed.