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--- robot [2015/08/08 00:43]
127.0.0.1 external edit
+++ robot [2015/12/15 16:10]
szsz
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 ====== The Capo Robot ======
-{{:wiki:robot:4wd1-robot-aluminum-kit.jpg?nolink|}}
+Designed mobile platform is composed of the following
+components:
+  - chassis,
+  - power supply
+  - control unit,
+  - motor drivers,
+  - sensors and other peripherals.
+Selected chassis is a Lynxmotion A4WD1 four-wheel body,
+cm long and width. The platform is shown in ﬁgure 1.
+{{:wiki:robot:capos.png?nolink&700|}}
+Fig. 1. Designed robotic platform based on A4WD1 chassis.
+Power is supplied by two LiPo batteries connected in
+parallel with the nominal voltage level 14.8 V and single
+battery capacity 5000mAh, which is sufﬁcient for several hours
+of continuous operation. Once the robot runs out of energy,
+batteries can be replaced without restarting the control unit.
+The main robot control unit is Pandaboard. Pandboard
+is a low-power low-cost single board computer based on the
+OMAP4430 dual core processor. Platform gives access to
+many of the powerful features of the multimedia processor
+while maintaining low cost. This will allow the user to develop
+software and use available peripherals in many conﬁgurations.
+The major components available on the PandaBoard, which
+can be used in the robot, are as follows:
+  * Power Management Companion Device,
+  * Audio Companion Device,
+  * Mobile LPDDR2 SDRAM Memory,
+  * HDMI Connector,
+  * SD/SDIO/MMC Media Card Cage,
+  * UART via RS-232 interface via 9-pin D-Sub Connector,
+  * LS Research Module 802.11b/g/n, Bluetooth, FM,
+  * Camera Connector,
+  * LCD Expansion Connectors,
+  * Generic Expansion Connectors,
+  * Composite Video Header.
+The device runs Linux kernel with either popular distribu-
+tion. The most basic task of the Pandaboard is to control the
+motor drivers – the RoboClaws
+The RoboClaw 2X15 Amp is an extremely efﬁcient, versa-
+tile, dual channel synchronous regenerative motor controller.
+It supports dual quadrature encoders and can supply two
+brushed DC motors with 15 amps per channel continuous and
+amp peak. With support for dual quadrature decoding it
+get greater control over speed and velocity is automatically
+maintains speed even if load increases. RoboClaw uses PID
+calculations with feed forward in combination with external
+quadrature encoders to make an accurate control solution.
+RoboClaw is easy to control with several built in modes.
+It can be controlled from a standard RC receiver/transmitter,
+serial device, microcontroller or an analog source, such as a
+potentiometer based joystick.
+To control the speed of motor RoboClaw uses pulse width
+modulation (PWM). Pulse width modulation is a method
+of adjusting the current or voltage signals, which consists
+of changing the pulse width of constant amplitude, used in
+ampliﬁers, switching power supplies and systems control the
+operation of electric motors. PWM powers the system directly
+or through a low pass ﬁlter which smoothes the voltage
+waveform or current.
+Because the Pandaboard and the RoboClaw works with
+different logic levels, a converter is required. For this purpose
+KAmodLVC logic level converter has been used. KAmod-LVC module is an 8-bit bi-directional converted voltage levels.
+The converter can be used to connect two digital systems
+operating with different voltages (like 1.8V and 5.0V in this
+case).
+The basic orientation sensors embedded in the robot in-
+cludes a gyroscope, accelerometer and magnetometer. The
+sensor can be used to determine the position of the robot in two
+planes. The diagram of components connections and relations
+is presented in Fig 2. The alignment of the components in the
+chassis is shown in Fig 3.
+{{:wiki:robot:robot-uklasd-elementow.png?nolink&300|}}
+Fig. 2. The block diagram of the robot components.
+{{:wiki:robot:robot-3d.png?nolink&300|}}
+Fig. 3. Internal design of the robot components.
+The central point of control and communication is the
+Pandaboard. This board has several communication inter-
+faces which are to control the robot effectors and to collect
+information from the sensors. Communication bus between
+Pandaboard and motor controller was realized using RS232
+interface. For the purpose of control only lines RxD and
+TxD are used. There is no hardware ﬂow control, because
+communication with the Pandaboard and RoboClaw is realized
+in inquiry respond method and it is always initiated by the
+Pandaboard. Therefore, if the control program waits for data
+from the controller it is not necessary to control rate. The data
+rate of this link is set to 38400bps.
+The orientation sensor uses serial I2C bus. To communicate
+with this bus the system uses duplex line Serial Data Line
+(SDA) and one-way line Serial Clock Line (SCL). Both lines
+are pull-up to power line so it is easy to detect transmissions
+collision using hardware. In robotic system this bus combines
+simplicity and functionality in one at a low investment of
+hardware and software to give the desired effect.
+Robot communication with the surrounding environment is
+based on the built-in wireless card: Pandaboard WiFi. Each
+robot has its own unique MAC address so it is possible to
+communicate with the selected robot even if a group of robots
+is working in the same network.
+Robot design provides an easy way for extending the range
+of sensors or effectors. It has been tested with ultrasonic sensors, laser rangeﬁnders, cameras and Microsoft Kinect sensor.
+Further extensions are possible using various interfaces: USB,
+COM, I2C or SPI.
+To determine the exact position of the robot can use the
+Global Positioning System (GPS) receiver or the more accurate indoor marker-based Hagisonic Stargazer system.
+Stargazer uses markers placed on the ceiling and on the basis
+of their positions it can determine the location of the robot
+with high accuracy. Another localization technique uses Hokuyo laser scanner and particle filter algorithm.
+Twenty units have been built in the course of the project for testing and further
+development purposes. The cost of all parts for a single unit
+does not exceed 900 USD, which is a very low price for the
+capabilities. The robot can develop speed of 3 m/s, it can put
+itself into vertical position by climbing a wall. It includes an
+on-board computer with 2-core CPU, running ordinary Linux
+OS and providing large variety of extension ports. It meets
+all deﬁned requirements for testing the planned applications.

robot.txt · Last modified: 2016/04/28 23:10 by szsz