& Masahiko Yamazaki Department of Aerospace Engineering, College of Science and Technology, Nihon University, Japan. What is sensor & actuator? 2. What is sensor & actuator as a satellite? Use case of satellite sensor & actuator 3. What is sensor & actuator as a CanSat What is in CanSat? Design example of sensor & actuator as a CanSat 4. Summary 2 What is sensor & actuator? The role of sensor &actuator is a device that detects and responds to some type of input from the physical environment. The specific input could be light, heat, motion, moisture, pressure, or any one of a great number of other environmental phenomena. The output is generally a signal. The main task of sensor is to detect a satellite condition, e.g. battery voltage, solar cell current, thermal and attitude, etc. is device that takes energy and converts it into some kind of motion. It is operated by a source of energy, typically electric current, fluid pressure, or air pressure, and converts that energy into motion. The main task of actuator is to control a satellite condition, e.g. orbit and attitude, deployment of solar panel and antenna, etc. 3 Indispensable components for a satellite Not only a single body performance but also consider relation with others. Component performance: Measurement range and accuracy. Other subsystems: C&DH subsystem(data control), Mission & ADC subsystem(data use), subsystem(data transmit). Peripheral circuit: A/D converter, amp, filter. Component Interface: Serial (UART, SPI, I2C,...), Discrete 4 What is sensor & actuator as a satellite? Bus system and Mission system Bus System System for survival in space and management of whole system Power subsystem Mission System e.g. experimental module, observation sensor,camera, Attitude determination and control (ADC) Structure Serial PWM Structure Command and Data handling (C&DH) Structure Thermal control (Harness)
What is sensor & actuator as a satellite? 5 Uplink 6 What is sensor & actuator as a satellite? Downlink Structure example Solar cell Battery Receiver Electrical power supply OBC Voltage Temperature Current Magnetism Sun lightdownlink Uplink Acceleration Angular velocity Memory S S2 Sn voltage, temperature, current, attitude sensors Experimental system Camera etc. Thruster Torquer Reaction wheel Mission Subsystem Solar cell 7 Transmitter Downlink Uplink example Reaction wheel Magnetic torque Ground Station & are closely related with C&DH subsystem. Data communication rate, Sampling interval, Memory size, Control interval, etc. Ground Station 8 & are closely related with other subsystems Electrical power supply,, Structure, Command & data handling subsystem. power consumption, data amount(memory size, sampling interval, downlink format), operation order, component layout, etc Downlink Uplink Downlink Uplink Ground Station Ground Station
Magnetic flux density [gauss] 9 [Operation order] Magnetic sensor (with radio communication noise).6.4.2 -.2 CW started Bx By Bz -.4 2 4 6 8 2 Time [sec] Temperature (Celsius) [Components layout] Thermal sensor (Inner and Outer components) Li-ion battery # Receiver Gyro # 2 Digi-talker 3 2 - -2-3 -4 2 3 4 5 6 7 Time (sec) Temperature (Celsius) Solar panel Solar panel 2 Solar panel 4 Solar panel 5 Solar panel 3 Solar panel 6 3 2 Eclipse - -2 Daytime -3-4 2 3 4 5 6 7 Time (sec) [Components layout] Sun sensor (Outer panel of CubeSat) 2 Use case of satellite sensor & actuator Attitude determination and control subsystem +. 22. - 2. [mm] + 2. 2. -. [mm] + 5.8 24.8-4. 8 [mm] Attitude determination = determination of the directional vector of each body axis Attitude control = to control the directional vector to required value sat sat sat sat R = é ù ê e e e ë x y z ú û
3 Use case of satellite sensor & actuator 4 Attitude determination and control subsystem Attitude determination sensor For example, extended Kalman filter by using sun sensors, geomagnetic sensors, and gyro sensors Use case of satellite sensor & actuator Attitude determination and control subsystem Attitude control actuator For example, 3 axis control by magnetic torquer Internal force Momentum wheel, Reaction wheel Reference direction Relative angle Sun sensor Control moment gyro Earth sensor Star tracker RF sensor Attitude control actuator Thruster Cold gas jet Monopropellant(catalytic hydrazine ) Bipropellant (oxidizer and fuel) for attitude determination Attitude motion Field Angular velocity Geomagnetic sensor Mechanical gyro Optical gyro MEMS gyro External force Gravity gradient torque Geomagnetic torque Ion engine Gas-liquid equilibrium thruster Extensible boom Magnetic torquer Acceleration Accelerometer Permanent magnet Relative position Position receiver Aerodynamic drag Dragshute Solar radiation pressure Deployable membrane 5 Use case of satellite sensor & actuator 6 Attitude determination and control subsystem Attitude control actuator For example, 3 axis control by magnetic torquer Internal force Momentum wheel, Reaction wheel Control moment gyro Use case of satellite sensor & actuator Attitude determination and control subsystem A/D converter, Filter and Amp. Attitude control actuator Thruster Cold gas jet Monopropellant(catalytic hydrazine ) Bipropellant (oxidizer and fuel) External force Gravity gradient torque Geomagnetic torque Ion engine Solar sail IKAROS Gas-liquid equilibrium thruster Extensible boom Magnetic torquer Permanent magnet Output Voltage (V) y z x Output Voltage (V) z y x Aerodynamic drag Solar radiation pressure Dragshute Deployable membrane Low pass filter for gyro sensor
7 Attitude determination and control subsystem Current control. Memory Data storage Use case of satellite sensor & actuator OBC Control input (digital signal) Current control (PWM, Motor driver) 8 Use case of satellite sensor & actuator Attitude determination and control subsystem Ex. De-spin control by Magnetic Torquer Amp Filter Output voltage (Analog signal) Gyro 3axis Pulse width modulation(pwm) Pulse Width Modulation is a simple method for controlling analog devices via a digital signal. It s a very efficient way to drive motors. Data storage Memory OBC Command (Digital signal) Output voltage (Digital signal) Control input AD convertor Current control (PWM, Motor driver) Galvanometer Magnetic Torquer Pulse width modulation 9 & are closely related with other subsystems (Electrical power supply,, Structure, ) and affected each other. power consumption, data amount(memory size, sampling interval, downlink format), operation order, component layout, etc It is important to extract performance as a system. It is important to consider the interference between sub-systems Downlink Uplink The mission sequence should be imaged well, discussed, and should be shared well in the team. CanSat? Ground Station
2 What is in CanSat? 22 What is in CanSat? Bus system and Mission system Bus System Mission System System for survival in space and management of whole system Power subsystem Attitude determination and control (ADC) e.g. experimental module, observation sensor, camera, Command and Data handling (C&DH) Structure (Harness) 23 What is in CanSat? 24 What is in CanSat? example Voltage Temperature Current Magnetism Sun light Acceleration Angular velocity example Motor & are closely concerned with other subsystems (electrical power supply, communication, structure, command & data handling) and affected each other. data amount(memory size, downlink format), number of sensor & example actuator, sampling interval(mpu spec), control algorithm, control interval, layout, noise(filter, Operation), etc Voltage Temperature The desired performance not by itself alone but as a system Currentis required. Magnetism Design the sensor & actuator under the consideration of Sunthe light communication and interaction with other subsystems. Acceleration Angular velocity example Motor
25 26 The mission sequence should be imaged well, discussed, and should be shared well in the team. Separation Imagine all the possible events and Separation anomalies which may happen on CanSat and prepare countermeasures for them as many as possible. Uplink Downlink Autonomous Flight Uplink Downlink Autonomous Flight Launch Ground station Objective point Launch Ground station Objective point 27 28 Step: and selection Consider requirement(weight, dimension), Separation environmental condition(vibration, acceleration, thermal), flight time, etc from past experience Consider Mission Sequence & clarify requirements () Set up CanSat and put it into a rocket and turn on switch A. (2) Rocket side prepare launch (you cannot contact and not Downlink predict the time) Autonomous Flight (3) Launch with Uplink high acceleration (CanSat may measure something in a rocket and write in memory) (4) CanSat Starts certain operation triggered by some switch at the timing of release from the rocket. (5) Downlink mission data as well as write in memory. (6) Landing may trigger also another actions. Launch Ground station Objective point ing: to be detected considering what kind of sensors are available and how easy to implement Temperature, Pressure,, Accelerometer, Sun light, Gyro, Ultra violet, Sound, Infra red, Actuation: available actuators, power, force, etc Motor, Nichrome line to cut nylon wire, Magnet, Utilization of shock of landing, Spring, Gravity, High level actions: combination of sensor, actuator & other systems Guidance/control with (comeback), camera, stand up, moving a er landing, Step: and selection What kind of sensors & actuator are available. How easy to implement Spec(How accurate?, How often?), Environmental tolerance, Power consumption, Data form(digital/analog) and Interface(I2C, Serial, UART), Size, Weight, Operating voltage )
29 Mission Example 3 Mission Example Launch! Save sensor data ( & Pressure) separation! Release from the Rocket deployment Altitude <=6ft release (Pressure & ) deployment separation! Direction control start! Power ON Direction control (Servo Motor & ) Landing Direction control start! 3 Mission Example Launch! Save sensor data ( & Pressure) 32 Receiver Transmitter 3.3V Regulator Release from the Rocket Altitude <=6ft release (Pressure & ) Battery 3.2V 5V Regulator Electrical power supply Pressure deployment deployment EEPROM OBC PWM Servo Motor Power ON Direction control (Servo Motor & ) 3.3V line 5V line 3.7V line Flag Relay switch Landing 3.2V line Data communication line Other line
33 34 Receiver Transmitter Analog with A/D converter, Filter and Amp. 3.3V Regulator Battery 3.2V 5V Regulator Pressure Electrical power supply EEPROM 3.3V line 5V line 3.7V line OBC PWM Flag Servo Motor Relay switch Digital 3.2V line Data communication line Other line 35 A/D converter A/D converter convert analog data from sensors into digital data. bit A/D converter can express analog data into bit digital data. In case of reference voltage is 5V V 3V 5V V~5V is expressed in 2=24 steps. 36 Serial & Parallel communication sending side input b7 b6 b5 b4 b3 b2 b b CLK Line Data Line receiving side output b7 b6 b5 b4 b3 b2 b b (I2C,UART,SPI, ) is a process of sending data one bit at a time, sequentially. Parallel communication Parallel communication is a process of sending data several data signals simultaneously over several parallel channels.
37 Servo motor 38 Servo motor Pulse width modulation Pulse width modulation(pwm) Pulse Width Modulation is a simple method for controlling analog devices via a digital signal. It s a very efficient way to drive motors. Sample Program. #include<6f877.h> 2.#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP 3.#use delay (CLOCK = ) 4.void main() 5.{ 6. int i; 7. while() 8. { 9. for(i=;i<;i++). {. output_high(pin_b3); 2. delay_us(5); 3. output_low(pin_b3); 4. delay_us(65); 5. } 6. } 7.} V+ V Pulse width =5us Period =8us 39 to cut nylon wire Separation! 5V +V PIC in R2 k Q PNP with Relay drive circuit PIC s high/low signal can control the relay switch condition(on/off). PIC signal High Low D + DIODE - Relay drive circuit Relay switch condition OFF ON VcSW STTL 3.2V + Nichrom Wire 4 Step2: and Assembly :System design & Operation check( & spec check) Spec(How accurate?, How often?), Environmental tolerance, Power consumption, Data form(digital/analog) and Interface(I2C, Serial, UART), Size, Weight, Operating voltage ) Battery 3.2V Electrical power supply EEPROM 3.3V line 5V line 3.7V line 3.2V line 3.3V Regulator 5V Regulator OBC Data communication line Other line PWM Flag Receiver Pressure Servo Motor Relay switch Transmitter
4 42 Step3: and Integration & Test Receiver Assemble sensor & actuator with other subsystem as Receiver a CanSat. Transmitter Transmitter 3.3V Regulator Battery 3.2V 5V Regulator Pressure Battery 3.2V OBC PWM EEPROM 5V Regulator Try as many ground testpower assupply possible in various settings Electrical operation of CanSat. Electrical power supply Integration is carried out taking into consideration the problem which may arise at the 3.3V Regulator Battery 3.7V time of integration. (CCA-552JZ) Power consumption, layout, algorithm, operation sequence, interference. Test is carried out to ensureobc normal operation of CanSat. (PIC6F877) Integrated check as PWM a CanSat), Environmental Servo Motor EEPROMtesting(performance (S32) Testing(thermal, vibration, etc), Calibration, Operation Testing Servo Motor Flag Relay switch Flag Relay switch Satellite or CanSat cannot always be experimented or confirmed under the 5V line circumstance that is similar to the real one. 3.7V line 3.3V line 5V line Pressure (PSM/2KPG) to ensure normal 3.7V line 3.2V line Results of number of connected in Dataexperiments communication line and confirmation tests are order to build a trustworthy system. Other line 3.2V line Data communication line Other line Structure 43 Electric power verification Test Launch! Save sensor data ( & Pressure) Release from the Rocket Altitude <=6ft release (Pressure & Nichrom wire) deployment deployment 44 Control Algorithm & Ground test Direction of movement Objective point () Neutral Right small turn 4.4 Main Battery 4.2 Direction control (Servo Motor & ) Voltage [V] Power ON Servo Battery 4 3.8 Waiting for launch 3.6 3.4 Servo system is ON(hour) Landing 3.2 Left large turn North latitude [deg.] Right large turn Left small turn 3 5 5 Time [sec] 2 25 East longitude [deg.]
45 performance test 46 Interference -MPU Wind-tunnel test Radio shielding sheet Flight Test 47 Interference - 48 Balloon experiment Balloon Magnetic flux density [gauss].6.4.2 -.2 CW started Bx By Bz -.4 2 4 6 8 2 Time [sec] OPEN ~5m Reel CanSat Ground Station 48
49 Balloon experiment 5 Step: Balloon experiment and selection What kind of sensors & actuator are available. How easy to implement Spec(How accurate?, How often?), Environmental tolerance, Power consumption, Data form(digital/analog), Size, Weight, Operating voltage ) Step2: and Assembly Step3: and Integration & Test Power consumption, layout, algorithm, operation sequence, interference, Integrated testing(performance check as a CanSat), Environmental Testing(thermal, vibration, etc), Calibration, Operation Testing North latitude [deg.] North latitude [deg.] Imagine the flight as completely as possible! It is important to consider the interference between sub-systems. Confirm the sequence of the mission, and check the validity of the sensor data and the actuator motion, the success of the communication, the power consumption of the batteries, and so on. East longitude [deg.] East longitude [deg.] 5 Operation mode control 52 Antenna deployment mechanism Mode Control Example by Level detection IC Low battery voltage Operation control High battery voltage Shunt control
53 Sun sensor For example, our SPROUT mounts 6 sun sensors 54 Sun sensor(using solar cell current) Hood Pinhole Sun sensor Position Sensitive Detector 55 Calibration 56 Manufacturing Bearing Torque rod Slide rail Bearing Coil wire
57 CanSat for CubeSat Summary In this lecture, I talked about Role of sensor and actuator. Design example of satellite and CanSat sensor and actuator subsystem. I think, The main task of sensor is to detect a satellite condition, e.g. battery voltage, solar cell current, thermal and attitude, etc. The main task of actuator is to control a satellite condition, e.g. orbit and attitude, deployment of solar panel and antenna, etc. Imagine the flight as completely as possible! Mission Objective Assembly, integration & test of part of CubeSat (, Data communication, Data save) Mission sequence simulation of part of CubeSat