Abstract:
A control device for a vehicle or mechanism includes a portable displacement controller which permits a non-technical user to achieve effective control of the vehicle or mechanism, by moving the portable displacement controller intuitively with little learning effort. A first sensing device, attached to the displacement controller, detects the user&#39;s controlling motion. A second sensing device, attached to the object being controlled, detects motion thereof. An interface device receives signals from the sensing devices, processes those signals to determine relative motion of the controlling motion and the object&#39;s motion and outputs a control signal in accordance with the processed signals. The sensing devices each detect motion in six degrees of freedom; the sensing devices each include a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. In specific embodiments, the accelerometers, gyroscopes, and magnetometers include micro-electromechanical system (MEMS) devices.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of provisional U.S. Application No. 61/309,886 filed Mar. 3, 2010, the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates to control devices, and more particularly to portable devices for controlling other devices capable of movement with multiple degrees of freedom (including but not limited to vehicles). 
     BACKGROUND OF THE DISCLOSURE 
     Conventional isotonic or displacement type of hand controllers such as joysticks and yokes rely on a cumbersome kinematic mechanism to restrict a human operator&#39;s three dimensional movements into a confined space. Mechanical linkages such as shafts, gears, bearings and springs, etc. are employed as necessary to transfer motions from the human operator to the electronic sensors attached to the mechanism. Widely used sensors such as potentiometers, transformers, Hall effect sensors, magneto-resistive sensors, optical and magnetic encoders, etc. can measure movement only along a single axis. Control devices employing these sensors make indirect measurements of the operator&#39;s movements and impose limitations on the design of a human machine interface (HMI). In order to provide a controller with capability in more than two DOFs (degrees of freedom), a conventional approach is to connect or stack several single- or two-axis mechanisms together. Controllers constructed according to this approach are complex to implement and awkward to use. In addition, using such a controller is not intuitive for the user; this lengthens the user&#39;s learning curve. 
     Due to inherent kinematic requirements, the mounting location and alignment of the sensors in such devices are often restricted, for example, to be at or near a pivot axis. Design flexibility and configurability are therefore limited. 
     Conventional control devices are often installed permanently to a fixed platform due to the size and weight of the kinematic mechanism. It is cumbersome to remove such equipment. In addition, when a conventional control device is mounted in a moving vehicle, the motion sensors therein may be susceptible to fictitious forces. Furthermore, these devices generally contain moving components that are subject to friction, backlash, binding, and deterioration over time and under changing environmental conditions, which thus impact their long-term reliability. Their size and weight often make such devices not suitable for portable or wearable applications. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with the disclosure, a control device is provided for a vehicle or mechanism. This control device includes a portable displacement controller which permits a non-technical user to achieve effective control of the vehicle or mechanism, by moving the portable displacement controller intuitively with little learning effort. 
     According to a first aspect of the disclosure, a control device includes a displacement controller operable by a user of the device. A first sensing device is attached to the displacement controller and is configured to detect a controlling motion performed by the user. A second sensing device is attached to the entity being controlled, the second sensing device configured to detect motion thereof. An interface device is operatively connected (via cable, or wirelessly) to the first sensing device and the second sensing device. The interface device is configured to receive signals from the first sensing device and from the second sensing device; to process those signals to determine relative motion of the controlling motion and the motion of the entity being controlled; and to output a control signal for controlling the entity in accordance with the processed signals. In embodiments of the disclosure, each of the first sensing device and the second sensing device is configured to detect motion in six degrees of freedom; each of the first and second sensing devices includes a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. In these embodiments, the accelerometers, gyroscopes, and magnetometers are micro-electromechanical system (MEMS) devices. The first sensing device detects the controlling motion relative to a first reference frame in accordance with a geomagnetic field local to the first sensing device, and the second sensing device detects the motion of the entity relative to a second reference frame in accordance with a geomagnetic field local to the second sensing device. In other embodiments, the displacement controller is wearable by the user; the displacement controller may be secured to the user&#39;s arm, hand or finger, to perform the controlling movement. 
     According to another aspect of the disclosure, a system for controlling a mechanism includes the above-described features and also includes an operating device (e.g. a host computing device) connected to the mechanism and configured to operate the mechanism. The interface device outputs a control signal to the operating device so as to control the mechanism in accordance with the processed signals. In an embodiment, the mechanism is a vehicle; the second sensing device, the interface device, and the operating device are located on the vehicle; and the displacement controller has the first sensing device disposed therein and is remote from the vehicle. In other embodiments, the displacement controller may be attachable to and detachable from a mounting base in the vehicle, or may be fixed thereto. 
     The foregoing has outlined, rather broadly, the preferred features of the present disclosure so that those skilled in the art may better understand the detailed description of the disclosure that follows. Additional features of the disclosure will be described hereinafter that form the subject of the claims of the disclosure. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present disclosure and that such other structures do not depart from the spirit and scope of the disclosure in its broadest form. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a Primary Sensing Module (PSM) and Secondary Sensing Module (SSM) used in embodiments of the disclosure. 
         FIG. 2  schematically illustrates a sensing module measuring accelerations and angular rotation rates in its own body coordinate system, in accordance with embodiments of the disclosure. 
         FIG. 3A  illustrates a single handle control device according to an embodiment of the disclosure. 
         FIG. 3B  illustrates steps in a calibration method for the control device of  FIG. 3A . 
         FIGS. 4A and 4B  are side and bottom views, respectively, of the single handle control device of  FIG. 3A . 
         FIG. 5  is a top view of a mounting base for mounting the single handle control device of  FIG. 3A . 
         FIG. 6  is a side view of the mounting base of  FIG. 5 , suitable for attaching to a vehicle platform. 
         FIG. 7  illustrates a dual handle control device according to another embodiment of the disclosure. 
         FIG. 8  is a side view of the dual handle control device of  FIG. 7 . 
         FIG. 9  illustrates another dual handle control device, according to an additional embodiment of the disclosure. 
         FIG. 10  is a side view of the dual handle control device of  FIG. 9 . 
         FIG. 11  schematically illustrates a Human Machine Interface (HMI) system including a Host Interface Module (HIM) connecting to a platform with an SSM, a controller with a single PSM, and to a host system, in accordance with an embodiment of the disclosure. 
         FIG. 12A  schematically illustrates a Human Machine Interface (HMI) system including a Host Interface Module (HIM) connecting to a platform with an SSM, to a controller with a multiple PSMs, and to a host system, in accordance with another embodiment of the disclosure. 
         FIG. 12B  schematically illustrates a moving platform communicating with a network of multiple interconnected PSMs, in accordance with another embodiment of the disclosure. 
         FIG. 13  schematically illustrates components of a HIM. 
         FIG. 14  schematically illustrates software executed by an HIM. 
     
    
    
     DETAILED DESCRIPTION 
     A control device according to the present disclosure is a displacement type control device operated by a human hand or hands, or a body segment when a human hand is not accessible. The device does not have conventional movement sensors and does not require a kinematic mechanism. Direct motion measurement is achieved by employing a combination of MEMS (micro-electromechanical systems) sensors arranged into modules, as detailed below. 
     Each MEMS sensing module contains a three-axis MEMS accelerometer, a three-axis MEMS gyroscope and a three-axis MEMS magnetometer in a compact package having a volume less than 0.2 cubic inch. Each module thus has the capability to measure acceleration, angular rotation rate and geomagnetic field in the sensing module&#39;s body coordinate system with respect to Earth. This capability provides a total of six degrees of freedom (DOFs), a significant advantage in terms of form factor over conventional electronic sensors. 
     In addition, the MEMS sensing modules do not contain any moving components, thus eliminating associated issues such as friction, wear, mounting restrictions, etc. Accordingly, a displacement controller embodying the disclosure offers the benefits of MEMS sensing technology, may be portable (or wearable), capable in multiple DOFs, and also adaptable to conventional devices involving kinematic mechanisms. 
     As illustrated schematically in  FIG. 1 , a control device  1  according to the disclosure includes a Primary Sensing Module (PSM)  11  and a Secondary Sensing Module (SSM)  12 . The PSM senses movement of a handle  13 , operated by a user of the device, relative to a platform  14 . Because MEMS inertial sensors rely on Earth&#39;s gravitational field for a reference frame, the effect of platform motions needs to be separated from the motions of control handle  13 ; this is done by measuring the platform motions using SSM  12 . The platform  14  serves as a reference frame for the motions of handle  13 ; the SSM senses movement of the platform relative to the environment. For example, platform  14  might be installed in a moving vehicle whose motion is detected by SSM  12 , while PSM  11  measures motions of handle  13  held by an operator. It is not necessary for handle  13  to be physically connected to platform  14 . 
     In this embodiment, PSM  11  includes a three-axis MEMS accelerometer  15 , a three-axis MEMS gyroscope  16 , a three-axis MEMS magnetometer  17 , a temperature sensor  18 , and a signal conditioning circuit  19  in a compact package having a volume less than 0.2 cubic inch. PSM  11  is attached to handle  13  at any convenient location. SSM  12  likewise includes a three-axis MEMS accelerometer  15 , three-axis MEMS gyroscope  16 , three-axis MEMS magnetometer  17 , temperature sensor  18  and signal conditioning circuit  19  in a compact package with a volume less than 0.2 cubic inch. In general, platform  14  is located where the control device is to be used; this may be (for example) a ground vehicle, a ship, or a human body. 
     PSM  11  and SSM  12  have power inputs  5 ,  6  and signal outputs  7 ,  8  respectively. PSM  11  also has inputs labeled “Mode”  2 , “Reset”  3  and “Enable”  4 , discussed in detail below. PSM  11  and SSM  12  are connected to a host system through a Host Interface Module (HIM), as shown schematically in  FIGS. 11-13 . 
     Each sensing module  11 ,  12  measures accelerations and angular rotation rates in its own body coordinate system. For example, with reference to  FIG. 2 , PSM  11  (disposed in the lower portion of handle  13 , as shown by dashed lines) measures accelerations of handle  13  in the x, y, and z linear directions and the pitch, roll, and yaw angular directions. Positional data including pitch, roll and yaw orientations are initially predicted using a navigation algorithm, discussed below with reference to  FIG. 14 . 
       FIG. 3A  shows some details of a portable single handle device  20  according to an embodiment of the disclosure. Handle  13  has an ergonomic grip portion  31  at one end and is attached to mounting plate  35  at its other end. PSM  11  is mounted to the opposite side of mounting plate  35  and is enclosed by an adaptor  36 . In a further embodiment, adaptor  36  is configured for mechanical connection to a mounting base, using ball detents  37 ; adaptor  36  also includes an interface connector  38  when the connection to the mounting base is not wireless. 
     Handle  13  is preferably rugged and ergonomically shaped for operation by a human hand or hands, or a body segment. In this embodiment, grip portion  31  includes “Mode” and “Reset” switches  32 ,  33 , the operation of which is described below. Grip portion  31  also has space to contain optional controls  28  such as switches, mini-joysticks, thumbwheels, etc. Controls and switches  28 ,  32 ,  33  in this portion of the handle are conveniently located for actuation by a user&#39;s thumb. 
     Because inertial motion sensors are always live when powered, unintended movements of the handle may lead to output errors. In this embodiment, such errors are prevented by recognizing sensor signals from the PSM only when “Enable” switch  34  is activated. “Enable” switch  34 , conveniently located for actuation by pressure from a user&#39;s palm, is activated only when depressed and deactivated when released. The host system connected to the device is notified when the “Enable” switch is deactivated, e.g. when the device is left unattended by the user or in the event the user accidentally drops the handle. The host system is configured to ignore undesired PSM outputs (that is, outputs while switch  34  is deactivated). 
     Alternatively, one or more SSMs may be mounted on the user (e.g. secured to the user&#39;s hand, arm or finger, or attached to or built into the user&#39;s clothing) to detect and cancel unintended user motion relative to the displacement controller (in this embodiment, single handle device  20 ). 
     “Reset” push button switch  33  is activated only when depressed and deactivated when released. Switch  33  is located for easy access as shown in  FIG. 3A  for a single handle grip (see  FIG. 7  for a dual-handle grip). The host system responds to a “Reset” signal (that is, when switch  33  is depressed) by resetting the digital outputs to default null values set during a previous calibration, and re-centering the device&#39;s output positions. This is analogous to using mechanical springs to return a conventional positioning device to a center position. In portable device  20 , there is no mechanical force present to return to a center position; instead, device  20  includes a non-volatile memory and “Reset” switch  33 . The memory holds the previous center position data and is refreshed until the “Reset” switch is depressed and released. The “Reset” button may be used to reestablish the reference frame of either or both of the PSM and SSM. The “Reset” switch has additional functions when combined with the “Mode” switch  32 , as described below. 
     In a further embodiment, grip portion  31  includes a “Hold” push button switch  39 ; depressing the “Hold” switch allows the user to bring the displacement controller back to a neutral position without altering the current displacement or orientation of the device under control (DUC). For example, a robot arm could be moved forward 24 inches by moving the displacement controller forward 12 inches, depressing the “Hold” switch, returning the displacement controller to its previous position, releasing the switch, and again moving the displacement controller forward 12 inches. (In this example, the user&#39;s controlling motion and the DUC motion have 1:1 scaling; other ratios may be used, as discussed below.) 
     “Mode” push button switch  32  is activated only when depressed for a period of approximately 5 to 10 seconds and then released. Activation of switch  32  causes the device to enter a calibration mode. The lengthened period required for activation ensures that the calibration mode is entered only when intended by the user. 
     Steps in a calibration procedure for a displacement controller device, according to an embodiment, are shown in the flowchart of  FIG. 3B . The user depresses the “Mode” switch  32  for approximately 5 to 10 seconds, and then releases the switch, to activate the switch (step  381 ). The user then moves the device in a full range of directions intended for use, and the device learns the geomagnetic field in its surroundings and angles relative to earth&#39;s gravitational field (step  382 ). The user then depresses and releases the “Reset” switch  33  (step  383 ). The device will then enter the calibration mode. During calibration, the user moves the displacement controller device only in the directions to be used for control purposes (step  384 ). By default, the device assumes that all six DOFs will be used. However, the user may select only a particular combination of three translations and three rotations (out of a total number of possibilities of 64, or 2 6 )—an analogy to mechanical gating in conventional control devices. The device learns that combination from the user&#39;s gestures (step  385 ). If the user believes an error has been made (step  386 ), the user presses and releases the “Reset” button to re-start the calibration. The user presses and releases the “Mode” switch again (step  387 ) to complete the calibration and exit the procedure. 
     It will be appreciated that a given user&#39;s set of motions and gestures may be applied to a variety of devices under control (DUCs). Conversely, a given DUC might be controlled by any of a plurality of users with differing types and ranges of motion. A user&#39;s calibration motions and gestures accordingly may be scaled to represent the dynamics of a particular DUC controlled by that user. For example, a child controlling a toy might cause the toy to move 6 inches in response to a 12 inch motion (scale 1:2), while a disabled person controlling a full-size vehicle might cause the vehicle to move 5 feet in response to a 1 inch motion (scale 60:1). 
     Furthermore, the system (which generally includes the displacement controller, HIM, SSM, and host system) may include a non-volatile memory and a display device, and may support control of a given DUC by a plurality of users, each having his/her own set of motions and gestures. In particular embodiments, the non-volatile memory is located either in the displacement controller, the HIM, or both. The calibration motions and gestures for each user may be stored in the non-volatile memory, and retrieved for use by the system in accordance with a user logging on to the system or selecting his/her name from a list of users displayed on the display device by the system. In an embodiment, the system may also include a device for signaling to the user when the user executes a motion or gesture outside the range of calibrated motions. 
     Alternatively, the system may be configured to perform a dynamic calibration of user motions (both intended and unintended motions) by monitoring and learning the dynamics of the system; that is, learning the types, DOF and range of motions performed by the user and detected by the displacement controller, by the SSM, and by the DUC. 
       FIGS. 4A and 4B  are side and bottom views, respectively, of the single-handle device of  FIG. 3A . “Enable” switch  34  is shown in profile in  FIG. 4A . In normal operation, handle  13  is gripped by the user so that “Enable” switch  34  is adjacent to the user&#39;s palm. A trigger-type switch  29  may be located on the same side of the handle, convenient to the user&#39;s forefinger. The bottom view of  FIG. 4B  shows fasteners  42  for the enclosure of PSM  11 , as well as ball detents  37  and alignment key  41  for positive mounting of adaptor  36  to the mounting base. 
       FIGS. 5 and 6  are top and side views, respectively, of a mounting base  60  on which portable single handle device  20  (such as shown in  FIGS. 3A and 4 ) is mounted, in accordance with an embodiment. As shown in  FIG. 5 , mounting base  60  includes a cradle  50  for connecting to adaptor  36 . Cradle  50  includes a keyway  51  for mating with alignment key  41 , and ball plungers  57  for mating with ball detents  37 . In a specific arrangement where handle  13  connects to base  60  via an interface cable, cradle  50  has an opening  58  for the cable. 
     Portable device  20  thus may be quickly attached to or detached from mounting base  60 . It will be appreciated that device portability removes the analogy for certain mechanical gating features such as cross-gate or speed shift gate. The adaptor  36  provides the user flexibility to switch between a portable device and a device fixed to base  60 , according to the user&#39;s preference. 
       FIG. 6  shows additional details of mounting base  60 . Cradle  50  connects to the lower portion of the mounting base via a flexible bellows or collar  62 . In this embodiment, mounting base  60  includes SSM  12  and HIM  61 , and interface connectors  67 ,  68  for connecting to the host system and the PSM respectively. Mounting base  60  is configured for attachment to platform  14 . When the platform is a moving vehicle, SSM  12  measures the motions of the vehicle and thus provides a frame of reference for the motions of the control handle. 
     A dual-handle controller  70 , according to another embodiment of the disclosure, is shown in  FIGS. 7 and 8 . Controller  70  has two ergonomic grip handles  751 ,  752 ; the user may activate “Enable” switch  74  using either hand. In this embodiment, PSM  11  is mounted in the central portion of the controller. Control panel  77  has space for various thumb-operated switches, including particularly “Mode” switch  32  and “Reset” switch  73 . Connectors  78 ,  79  permit attachment of interface cables if required.  FIG. 8  is a side view of controller  70 , showing the right-hand grip handle  752 . PSM  11  is mounted to mounting plate  85  in the interior of the controller. “Enable” switch  74  protrudes from the exterior surface of handle  752 , convenient to the user&#39;s palm. In normal operation, the control panel  77  is convenient to the user&#39;s thumb, while a trigger-type switch  87  is located on the opposite side of the handle, convenient to the user&#39;s forefinger. 
     Another arrangement of a dual-handle controller, according to a further embodiment, is shown in  FIGS. 9 and 10 . As shown in  FIGS. 9 and 10 , controller  90  is a two-axis controller, measuring azimuth rotation (yaw)  95  and elevation rotation (pitch)  105 . Controller  90  has two ergonomic grip handles  931 ,  932 , each having an area  97  with space for thumb-operated switches. In the central portion  94  of the controller, PSM  11  is mounted on mounting bracket  92  in the central portion  94  of the controller. Mounting bracket  92  is connected to elevation shaft  91  running between the grip handles.  FIG. 10  is a side view of controller  90 , showing the right-hand grip handle  932 . In the embodiment shown in  FIG. 10 , the central portion  94  of controller  90  mounts onto mounting base  108 , so that controller  90  and mounting base  108  are connected by azimuth shaft  106 . Similar to the arrangement of  FIG. 6 , mounting base  108  includes SSM  12 , and has an attaching portion  102  for attachment to platform  14 . When the platform is a moving vehicle, SSM  12  measures the motions of the vehicle and thus provides a frame of reference for the motions of the controller handles. 
     PSM  11  in controller  90  measures both azimuth rotation about azimuth shaft  106 , and elevation rotation about elevation shaft  91  (see also  FIG. 2 ). Separate sensors for the azimuth rotation and elevation rotation are not required as in conventional arrangements. This serves to illustrate the simplicity of controllers using MEMS sensing technology. 
     It is understood that controllers embodying the disclosure may have a variety of sizes, shapes, and configurations, and that the examples described herein of single-handed and dual-handed controllers are not limiting. 
     In accordance with another embodiment, a Human Machine Interface (HMI)  115 , which serves as an interface between a user  100  and a host system  135 , is shown schematically in  FIG. 11 . The HMI includes a controlling device  111  with PSM  11 , a platform or mobile reference  14  with SSM  12 , and a Host Interface Module (HIM)  131  which contains electronic hardware and software. The hardware includes a digital signal processor, a microprocessor as CPU, non-volatile memory, and a digital interface for communication with the host system. In this embodiment, the controlling device, platform, HIM and host system are interconnected using cables  110 . (In general, cables are used only when wireless communication between components is not preferred.) The HIM  131  may be mounted on the platform  14  or at another convenient location. In particular, the HIM  131  and SSM  12  may be combined into one module for ease of portability. 
     In a particular configuration of HMI  115 , according to an embodiment, the PSM is user-wearable; that is, mounted onto the user  100  (e.g. secured to the user&#39;s arm, hand or finger), or attached to or built into the user&#39;s clothing. Thus, in a remote weapons control application, a soldier may control the weapon by movement of his arm, hand or finger. 
     The relationship among PSM, SSM and HIM is shown in  FIG. 11  for a simple HMI system which contains a single PSM/SSM pair. A more complex HMI system  125 , serving as an interface between user  100  and host system  135 , is shown schematically in  FIG. 12A . HMI system  125  includes a controlling device  121  with multiple PSMs  11 - 1 ,  11 - 2 , . . . ,  11 -N and a platform  14  with a single SSM  12  used as a common reference. 
     In additional embodiments, the PSM/SSM configuration shown in  FIG. 12A  can be re-arranged so that multiple PSM/SSM pairs are formed by using a given PSM as its neighbor&#39;s SSM at the same time, thereby creating a powerful sensing network in order to match the DOFs of a complex system. 
     In further embodiments, multiple PSMs may be linked together to form a network  151 , as shown schematically in  FIG. 12B . The PSMs  1511 - 1 , . . . ,  1511 - 4 , are linked to each other in network  151 , as well as being linked to SSM  1512  on moving platform  1514 . 
     One or more SSMs, or combined SSM/HIM modules, may also be mounted on the user (e.g. secured to the user&#39;s hand, arm or finger, or attached to or built into the user&#39;s clothing) and connected in a network to detect and cancel unintended user motion relative to the displacement controller. In addition, the host system may be configured to monitor the environment for adverse operating conditions (e.g. magnetic disturbances) causing loss of performance, and provide an indication thereof to the user. The user may then compensate for the loss of performance by using alternate motions or gestures, or instead using conventional devices to operate the DUC. 
     Some details of HIM  131  are shown schematically in  FIG. 13 . HIM  131  includes a CPU  133 ; a non-volatile memory  134 ; and a digital interface  136  for communicating with host computer  137 . Software resident in HIM  131  includes software  132  for digital signal processing and command handling. Inputs to the HIM  131  include power  5 , PSM signals  7 , and SSM signals  8 . 
     The host computer  137  or HIM  131  may have stored therein information relating to a plurality of users. In an embodiment, a stored user identifier is associated with that user&#39;s control motions and gestures, and is also associated with a security status of the user. (The security status of a user is sometimes referred to as a permission level for that user, indicating whether a user has permission to access certain features of the system.) The controlling effect of a user motion or gesture may be altered in accordance with the user&#39;s security status. 
       FIG. 14  shows the software scheme  140  for HIM  131 , schematically illustrating software executed by CPU  133 . A real-time signal acquisition procedure  141 , accepts inputs  1401 ,  1402  from the PSM and SSM. Positional data including pitch, roll and yaw orientations are initially predicted using a navigation algorithm  1410 , by integrating the angular rotation rates over time. This integration algorithm is similar to a strapdown algorithm commonly used for an inertial navigation system. To avoid drift induced by integration, the orientation data are then re-predicted by using accelerations. Since accelerations cannot distinguish between inertial and gravitational forces, drift errors with respect a given axis are resolved by using magnetometers. Because each geographic location has different magnetic field components and local distortions, the user needs to calibrate the device (using the “Mode” button; see  FIG. 3B ) at its first use or when there is a change in the control device&#39;s surroundings that may affect the magnetic field. Predicted results are subject to noise errors and thus further corrected by a Kalman filter  1403 , which works well for normally distributed noise. As noted above with reference to  FIG. 2 , the PSM and SSM each measure accelerations and angular rotation rates in their respective body coordinate systems. Software component  1404  transforms the PSM positional data to the SSM body coordinate system, thereby relating the user&#39;s hand motions to the frame of reference of the device (e.g. vehicle) being controlled. Software components  1405 ,  1406 ,  1407  process inputs from the “Enable”, “Mode” and “Reset” switches respectively, and initiate the corresponding operations (e.g. process inputs from the PSM while an “Enable” input is also present, and ignore inputs from the PSM otherwise). Additional software components  1430 ,  1408  input and process commands from the host system  135 . (For example, in response to a command from the host  135 , the CPU  133  might prepare an updated control instruction from the user, based on the PSM and SSM data.) The result of the processing by software  1408  is transferred to software  1409  for outputting to the host. 
     Embodiments of the present disclosure may thus be used in portable or fixed controls; single- or dual-use controls; and single axis, two-axis, or three-axis controls. Control devices constructed according to the disclosure may be used in a variety of applications, including control of cameras and forward-looking infrared (FLIR) imaging systems; flight control, including control of unmanned aerial vehicles; payload control; control of remote weapons, unmanned ground vehicles, unmanned surface water vehicles, and unmanned subsurface water vehicles; control of medical devices and robotic arms; and control of construction equipment and earth moving equipment. Furthermore, the compact and rugged nature of MEMS PSM and SSM components permits these control devices to be weapon-mounted or human-wearable in rugged environments (e.g. by gunners or special operations personnel). Other applications include wearable control devices for persons with disabilities or rehabilitation patients. 
     While the disclosure has been described in terms of specific embodiments, it is evident in view of the foregoing description that numerous alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the disclosure is intended to encompass all such alternatives, modifications and variations which fall within the scope and spirit of the disclosure and the following claims.