arrow_back_ios

Main Menu

See All Acoustic End-of-Line Test Systems See All DAQ and instruments See All Electroacoustics See All Software See All Transducers See All Vibration Testing Equipment See All Academy See All Resource Center See All Applications See All Industries See All Insights See All Services See All Support See All Our Business See All Our History See All Our Sustainability Commitment See All Global Presence
arrow_back_ios

Main Menu

See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All DAQ Systems See All High Precision and Calibration Systems See All Industrial electronics See All Power Analyser See All S&V Hand-held devices See All S&V Signal conditioner See All Test Solutions See All DAQ Software See All Drivers & API See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All Utility See All Vibration Control See All Acoustic See All Current / voltage See All Displacement See All Load Cells See All Pressure See All Strain Gauges See All Torque See All Vibration See All LDS Shaker Systems See All Power Amplifiers See All Vibration Controllers See All Accessories for Vibration Testing Equipment See All Training Courses See All Whitepapers See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Smart Sensors See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All Our People
arrow_back_ios

Main Menu

See All CANHEAD See All GenHS See All LAN-XI See All MGCplus See All Optical Interrogators See All QuantumX See All SomatXR See All Accessories See All Accessories See All BK Connect / Pulse See All API See All Microphone Sets See All Microphone Cartridges See All Acoustic Calibrators See All Special Microphones See All Microphone Pre-amplifiers See All Sound Sources See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All Accessories See All Non-rotating (calibration) See All Rotating See All CCLD (IEPE) accelerometers See All Charge Accelerometers See All Impulse hammers / impedance heads See All Cables See All Accessories See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

Development of a 3-axis Force Sensor Based on HBK Strain Gauges

the Technical University of Darmstadt, GERMANY

Introduction

How can a passive and cost-optimized sensory foot for load-bearing walking robots be developed? This research question was approached as part of a robotics project of the Simulation, System Optimization and Robotics Department of the Technical University of Darmstadt.

With the help of HBK strain gauges for transducers a 3-axis force sensor was developed to regulate the motion control of the robot.

chevron_left
chevron_right

Development of a passive sensorial foot for load-bearing walking robots that is more cost-effective than the sensors available on the market.

The Setup of the 3-axis Force Sensor

The 3-axis force sensor is based on an aluminium feather-spring component in a cylindric beam-structure. This setup is easy to produce and cost-effective.

To measure the forces in x, y, and z direction, three strain gauge full bridges were installed: 

  • Measuring the z direction: Four transducer strain gauge rosettes K-TA11K3/350  were installed inside the feather-spring component with a cold curing two-component adhesive.
  • Measuring the x  and y direction: Eight transducer strain gauges K-LU13K1.6/350 were attached outside of the feather-spring component. Due to the stick-on design the transducer strain gauges could be applied hot and user-friendly.

The strain gauges are arranged like demonstrated in the figure 1. Strain gauges number 1-4 measure the z direction, strain gauges 5-12 measure the x and y direction. 

 

The Test Run of the Prototype

To verify the 3-axis force sensor, a prototype was developed. Based on HBK strain gauges for transducers a 3-axis force sensor was developed to regulate the motion control of the load-bearing walking robots. Due to a pre-coated adhesive layer, the processing of the strain gauges was not only very easy and process-optimized, but also delivered very good results.This prototype was evaluated and calibrated in a first test run. With the help of the calibration devices, the spring body is loaded one after the other in the three force directions.

The calibration conditions for the input and output were as follows: 

Zero signal x-channel (mV) 11.42
Zero signal y-channel (mV) 5.13
Zero signal z-channel (mV) -28.90
Power supply voltage (DC current in V) 3.3
Amplifier ADS1262
Measuring Range (V) +/- 0.156
Gain factor x-channel  16
Gain factor y-channel 16
Gain factor z-channel 16

The Results of the Test Run

The calibrated measurement curves are shown in the orange, green and black graphs. As a comparison value, the reference force measurement is also shown in the blue graphs.

Mean absolute deviation from the reference sensor and average relative error:

Force direction Mean absolute deviation (N) Average relative error (%)
Fx approx. 3 approx. 1.5
Fy approx. 4 approx. 2.6
Fz approx. 23 approx. 3.1

The results of the first test run clearly show that considerable results have already been achieved with HBK standard strain gauges. To further optimize the results of the mean absolute deviation and the mean relative error, a follow-up project is being conducted at the Technical University of Darmstadt.  

About the Technical University of Darmstadt

The Technical University of Darmstadt is one of the leading technical universities in Germany with high international visibility and reputation. Since its foundation in 1877, the TU Darmstadt has been characterized by a special pioneering spirit. Through outstanding achievements in research, TU Darmstadt opens up important scientific fields of the future. 

More about Technical University of Darmstadt

Technology Used

Related Case Studies