PowerForce System. User manual - wireless edition. PowerForce User Manual

Transcription

1 PowerForce System User manual - wireless edition

2 Inhalt Important warnings Introduction Pedal forces Force components... 5 Fr (resultant / total force)... 5 Fe (effective / tangential force)... 5 Fu (unused / radial force) Measuring Principle Technical Data Wireless edition After unpacking components Mounting Software Installation Install NI-DAQmx Driver Install NI LabVIEW 2009 Runtime Engine Library Install IMAGO Records IMAGO Record Introduction First start and setup Load Setup-files Set, save and load calibration values Description of IMAGO Main Menu Index Tab Measurement CyclePlotAssistent Quick buttons and contents Charts and Design Graph Selection Caption and legend Save quick button... 28

3 Important warnings Please read the following warnings, before beginning to use your PowerForce System. Otherwise, your PowerForce could be damaged, or not function properly. Do not over tight the pedals in the PowerForce System. Give some grease to the connective sites to improve the reassembling of the pedals. If your open a sensor, the transmitter unit or the connection box, the warranty is no longer valid. Never clean the sensor or the transmitter unit with water or use it in wet conditions. Do not cramp the position switch it is sensitive for pressure. Check before each ride, that the sensors and the pedals are fixed properly. When unplugging any connection, always pull straight down rather than sideways, or you could damage connector pins. Never pull on the cable itself, but rather the plug. Carefully read through the full installation instructions before beginning, as mounting the PowerForce System incorrectly can cause a fall or damage the system. Do not load the sensor with loads higher than 300kg.

4 1.1 Pedal forces 1. Introduction In cycling the transfer of metabolic energy into physical power or velocity of the rider-bike-system is not one-to-one. Environmental as well as mechanical and biomechanical factors affect cycling performance. The propulsion of the bike is generated by pedal forces. Therefore, the determination of pedal forces is a major prerequisite to analyze cycling performance capability from a biomechanical point of view. The question is not why to measure pedal forces but how to do it. Comparing other existing instruments whose purpose is the determination of divers mechanical parameters concerning cycling propulsion, there are some methodological or practical limitations regarding the requirements of either a biomechanical lab or a sports related center. The most important advantage of the PowerForce System is the fact that there is no restriction to a certain pedal system. Cyclists do not have to change their pedal-shoe interface (cleats) if they want to measure their pedal forces with the PowerForce.

5 1.2 Force components The PowerForce records the forces, which are performed on the pedal axis, separately for each leg. Three force components (Fe, Fu und Fr) have to be differentiated. Fr (resultant / total force) This is the total force which is generated by the athlete on the pedal. It is the vectorially sum of Fe and Fu an is calculated, not measured. Fr tells us about the total load, the rider applies to the system the bike as well as to his own body. Joint moments and forces result from (or cause) this component. Thus, e.g. inverse dynamics are based on Fr. Fe (effective / tangential force) Fe is the component of Fr which lies in moving direction of the crank/pedal which is a circle. Therefore, the vector of Fe is always tangential to this circle or perpendicular to the crank. Fe is responsible for the propulsion, but only if it is aligned forward with the rotating direction. If it is aligned backward, e.g. if a rider does not pull up the pedal in the upstroke phase, Fe of the one side must be subtracted from the other side. Fu (unused / radial force) Fu is the component of Fr which does not generate any propulsion. It results in very small deformation of the crank and pedal-axis. The direction off this force component is lengthwise to the crank. The highest values appear around the bottom dead center (180 crank angle) where the weight component (induces by the mass of the leg) adds to the muscular component.

6 1.3 Measuring Principle The pedal force measuring device is built as an own mechanical construction which is mounted between the crank and the pedal with an 12 forward rotation about the crank. The system determines the magnetic field variations (Hall-Effect) because of the angular displacement (~ 1/1000mm) of a small magnet in respect to a sensor. Due to the specific circular construction of the force transmitting elements the applied force can be divided into a radial and a tangential part. Positive tangential force (FT = Fe) is in the pedaling direction and positive radial force (FR = Fu) is in the centrifugal direction. This principle allows every pedal system to be screwed on. new (virtuell) crank arm 12 pedal

7 1.4 Technical Data Wireless edition Mass of single sensor including radio: 370 g Mass of receiver: 116 g Measurement range: -500 up to 1500 N Breaking load: ~3000 N Sampling frequency pedal force: ~500 Hz Wireless band: ISM Band: 2,4 GHz Transmission distance: Indoor: 3 5 m Outdoor: 2 3 m Battery Type: NiCd 800 mah Time for continual use: 6 8 h Resolution: 12 Bit

8 2. After unpacking First read and follow these instructions! Unpack all materials very carefully! The PowerForce System is high sensitive electronic. So, handle all parts with highest care 2.1 components Check the content inside the suitcase [1] 2x PowerForce sensor (left & right), with mounted transmitter (Accumulator included, two protector caps mounted) [2] 1x Base station (receiver) [3] 1x Adjustment Tool [4] 2x adjustment tools screws [5] 2x crank sensor screws [6] 2x Accumulator Charger [7] 1x Serial USB cable (Base station to PC) [8] 1x USB License Dongle [9] 1x 10mm Allen Key [10] 1x 2,5mm Allen Key [11] 1x 10mm Wrench [12] 1x Calibration printout

9 2.2 Mounting To improve the measurement, it is important to fix the sensor in appropriate position on the ankle. Before the mounting, make sure, that the adjustment screws are screwed out: so, that the sensor has some space to move. Then mount the sensor on the crank:

10 Adjust the apex on the cone-bolt. Put the little bolts in the middle and fix the adjustment tool (handtight) onto sensor, by using the corresponding screw for each site: Put the cone of the adjustment tool into the center of the bottom bracket screw:

11 Then fix the sensor using the two adjustment screws. Tighten the screws alternating. It means first a little the left, then a little the right, until the screws fixing the sensor in position. Make sure, that the cone of the adjustment tool stays in the center of the bottom bracket screw: After the adjustment screws fixing the sensor, tight the sensor crank-screw: Then you can take off the adjustment tool.

12 3. Software Installation For the installation of the PowerForce software you need to download the software package on our homepage: Install NI-DAQmx Driver Before you install the IMAGO Record-Cycle Software, you must install the NI-DAQmx-Driver. Click on the icon in the saved file and follow the setup instructions. The Installation will take some minutes. 3.2 Install NI LabVIEW 2009 Runtime Engine Library After installing the DAQmx Driver, you must install the NI LabVIEW Runtime Engine. This library is necessary to read out the data from IMAGO. Click on the icon and follow the setup instructions. The Installation will take some minutes. 3.3 Install IMAGO Records After the previous installation, you can install IMAGO Record. Therefore, you must open the setup.exe and follow the setup instructions.

13 4.1 Introduction 4. IMAGO Record IMAGO is a LabVIEW based program developed at the University of Freiburg for data acquisition and processing. The cycling lab (Radlabor ) out a lot of effort into the development of this software. The PowerTec measurement device and the IMAGO software are developed parallel and are therefore well concerted. Besides force measurements, any other analogue channel can be recorded in IMAGO. The program also includes a processing routine. The data output from this routine is a MS Excel (2003) sheet containing the mean of all recorded channels resampled to 360 data points (1 steps). It was developed for movement analysis with the PowerTec pedal force measurement system and EMG recordings. For training and training studies the program provides an online feedback. This feature, called Cycle Plot simplifies the data stream in a circular graph, to enable any athlete to work with feedback without previous knowledge. As the program has many more features used at the University, which are not available in your version, there might be a few buttons and other options, which have no further relevance for pedal force measurements. But as far as possible, they are hidden or deleted. If you have any further questions, please contact the Radlabor. 4.2 First start and setup Start IMAGO Records by clicking on the Icon on your desktop. Make sure, the USB-license dongle is in your PC, otherwise this error message may occur: In this case close the program, insert the right dongle and restart IMAGO Records. Your system firewall might want to block the application. You should allow the Imago record.exe to pass the firewall.

14 On the first time, you start IMAGO two windows will open: - The main record window (IMAGO record.vi) - and a window with the overview of all channels (Wireless Cycling Instrument.vi) Load Setup-files To load the optimum setup files, you must click on setup. Find the folder record on the following data path Then you can insert the downloaded setup file called RECORD_CYCLE1.set. After this step, the optimal set-up settings should be present in IMAGO.

15 4.2.2 Set, save and load calibration values To enter the calibration parameters, you need the calibration protocol, which was attached to the case. There you can see the offset settings and the correction values that were determined during the calibration of your system in the Radlabor Company. Now enter the, for your system, individual parameters in the Wireless Cycling Instrument.VI as seen in the picture. Note, that the gain for the power channels must be calculated with 500 N to get from the voltage in V [V] to the force in [N]. Then press on the save button to save these parameters. You can find these settings under the file path:

16 To have these settings at each start of IMAGO you need these. set files loaded in the Read Write Global Variables.VI. You find this VI under the path: Options Extras Paths Then you must load the set files as shown in the picture: After these adjustments, your system is ready to use.

17 4.3 Description of IMAGO The following chapters describe some of the most common functions in the analyze software IMAGO Recors Main Menu IMAGO In this Tab, you are able to select the point, that IMAGO is always selected. During the processing routine, some settings need to be confirmed. But you can also let the system confirm most of the automatically. To stop this automatism, you need to switch the Always Active option. Further here is the setting the page and for printing the actual window. Beenden means to close IMAGO. Tools Via the Tab Tools you can do the Binary Export. You need this binary export to transform your binary data in an excel readable file format, e.g. for analyzing the separated force channels or the acceleration channels. Extras Here you can select further options. If you click on it, a window appears with four different index tabs. In the tab General you can select your decimal separator, which is set to your Excel version. This setting is dependent on your country and the way MS Excel reads decimal numbers.

18 Under Recording you can adjust some settings of the inserts of channels like the first channel of the analog/digital-converter or the beginning position of your digital trigger channel. In Instruments you can select different instruments- and wireless selections of the PowerForce systems. But in usual case you should take the default selections. The paths are already described in chapter Help Via the Help -tab you have three selection possibilities. If you select WOZU KONTEXTHILFE? If you select About IMAGO, you can check which version of IMAGO you have. Further you can see the key number of your USB-license-dongle. Under User Manual you can call up further usage instructions for IMAGO Records. To this your PC must be connected to the internet Index Tab Via the Index Tab you can choose different viewing possibilities while the data acquisition. Index tab Record After the use of the measurement button you can follow the actual course of the curve in the record-window. All selected channels are displayed in this window. By moving the bar on the left side of the window you can change the viewing area.

19 Index tab cycle plot The cycle plot window plots circular forces. An additional curve shows the summation of both force signals. Above the cycle plots you see different index tabs: The power tab shows you the generated power of the left and the right leg, as well as their summation. In the settings, you can set the start angle, the crank length and the used data pieces. Index tab Wireless Before you start the measurement, it is recommended to check the wireless-connection of your PowerForce system. So, you have an overview about the current wireless signals in [V], the base station receives. Under the wireless signals you see an overview about the arriving frequency samples. Usually they are about 500 Hz (1). When you just turned on the System it takes a few seconds until the transmitter is booted and the maximum sample frequency is reached. Further you see a button for manual time correction and an overview about the number of connection interrupts.

20 If you notice a high increasing number of interrupts it may occur because of an interference of your Wi-Fi-Signal or a damage on the transmitter unit.

21 4.4 Measurement To start pedal force measurements, click the measure button. A pop up window will open where filename and information about the trial can be entered. All channels defined and marked green in the channel definition instrument are listed in this window. A second selection which channels you want to record must be made. Select the trigger and all four force channels by marking them green. After continuing a red line will run across the screen writing and overwriting the recorded values in the graph. If you click on the Cycle Plot register and start pedaling, red circles can be seen. These circles display the current forces relative to a black reference circle. The black circle is the zero line. The further the red line is outside the circle, the bigger is the force. The further it is inside, the bigger is the measured negative force. The displayed channels can be changed above the charts. The power calculations depend on the crank length, which has to be entered below the cycle plot window. If the Trigger is not installed at the top dead center of the right crank arm, the offset can be entered as well. To start data recording click the RECORD button. You can pause data recording by clicking this button again and finish the trial with STOP. While recording the RECORD button is green and a timer depicts the seconds written. As soon as you press the STOP button, the program will ask you if you want to start Online processing. If you confirm, a second window will open and ask, which data you want to include for your results. This is a control routine, which compares the length of data pieces between two trigger signals to the average length. The tolerance interval is +/- 20% of the average signal length. If you have no accelerated movement, there should not be more than one or two signals, which vary. This is usually the last signal, because recording stops at most times less than one revolution after the last trigger signal.

22 5. CyclePlotAssistent The Cycle Plot Assistant was developed to display the force data recorded with IMAGO Records. It is based on Excel 2007, but an older Excel 2003 Version is also available, which is containing less functions. The Tool is written in Visual Basic for Applications. When you open CyclePlotAssistant.xltm, the first step you need to take is to activate Macros for this Workbook. You start the CyclePlotAssistent by click on the Icon. Make sure, that the macro files are in the same folder as the application. So, its recommended to create a shortcut of the CyclePlotAssistent on the desktop.

23 After the start of CPA, you see different icons. If you click on Main_Menu you can open the menu. By clicking on the arrows above Zero circle you can change the size of the zero circle for cycle and vector plots. It Has no relevance for other charts. In the box of graph size you can change between maximal amplitude for all graphs or the same proportion (standard).

24 5.1 Quick buttons and contents The file icon opens the *.xls files you want to display (they must be recorded with IMAGO). The white cross on red background next to the file icon unload the selected files. The blue numbers are quick load buttons. Once you have created a sheet, you can save your settings and apply it to other data with these buttons.

25 5.2 Charts and Design Here you can select different chart types. All available charts are shown below. The sheet is divided into six areas, where charts can be plotted. There are also description fields available. If you click on Corner, Caption or Header you can arrange the header and the headline of the print sheet. The information is taken from the loaded raw data files. Multiple choices are impossible. Cycle: In this chart the data is plotted in a circle. The black circle is zero. Positive data is outside the black circle. Negative data is inside it.

26 Vector: Every ten Data Points the vector of one or two selected channels (Fe and Fu coordinate) is displayed at the according crank position. Note, that the first coordinate is always the direction of Fe, the second always that of Fu. Two different channel pairs can be shown in one graph. XY-Graph 5.3 Graph Selection Here you can see which file is represented by data1, data2, data3 and data4. The button details open the detail-window. This appears in the right part of this window and all selected graphs are shown there. To create new Quick Buttons, it might be easier to work with this view.

27 Click on the chart position, to add graphs to the according chart To display the same selection in one line, this button graphs in one row. applies the selected buttons to both In the data selection, all recorded channels will be shown in the left drop down menu Up to 4 graphs can be plotted in one chart. 5.4 Caption and legend Add manually Comments, which can be added to the header, label or legend (1) Similar to the overview for the graph selection an overview window for the top bar and legend labels exists. The left list represents the Top bar selection, the right one the legend selection. Multiple choices are possible. (2) By clicking on the chart position you can apply a name to the Chart in the Top bar and a description with the color of the graph in a legend underneath the chart. (3) If you want to assign the same parameters to all charts you can do this by using this button, which selects all charts

28 5.5 Save quick button If you click on one or more than one of the Buttons, you can use the functions of the Buttons below on the selection. These two tables correspond to the Quick Load Buttons in Main Menu You can Hide and Show the Buttons in the Main Menu. This is simply a possibility to tidy up the menu. With the Button assign settings to Button all Indices of the current selection (charts, comments, graphs, legends and header entries) are saved. Note that only the indices are saved. Meaning, that if you have selected the second recorded channel of your file the second channel of the new selected data you apply your settings to will be shown. There is no reference to the selected channel name. By clicking on New Button Name you can change the name of the button without changing the settings applied to it. Radlabor GmbH Heinrich-von-Stephan-Str. 5c Freiburg im Breisgau Phone: + 49 (0)761 / Fax + 49 (0)761 / support@radlabor.de AGFreiburg, HRB CEO: Bjoern Stapelfeldt